Forensics Science for the Classroom Teacher

Forensics Science for the Classroom Teacher
Project Description: Training for the junior high and high school science instructors. Forensics Science for the Classroom Teacher February 5, 19, & 26 Presented by: Nihal Behrens Dr. Kathy Brock Brian Albrecht Nihal Behrens Project Director Program Chair Science Ed Outreach This project is funded by a grant awarded under the President’s Community Based Job Training Grant as implemented by the U.S. Department of Labor’s Employment and Training Administration (CB ).

For the Classroom Teacher
Forensics Science For the Classroom Teacher Presented by Nihal Behrens February 5th, 19th & 26th 2007

Outline Introduction Analytical Techniques Fingerprints Blood
DNA profiling Hair Firearms Glass and Soil Paint Fiber

Analytical Techniques
Introduction & Analytical Techniques

Introduction What Is It?
Forensic science Application of science to law Physics – ballistics Chemistry – fingerprints, glass, instrumentations Biology – DNA Geology – soil in its broadest definition Source: (Richard Saferstein, 1981, Criminalistics—An introduction to Forensic Science, 2nd edition, Prentice Hall)

Introduction What Do They Do?
Forensic scientist Assists Department of Public Prosecutions (DPP) to determine if a crime has been committed or not Assist in identification of perpetrator of crime Analysis of physical evidence Provision of expert testimony Furnishes training in proper recognition, collection, and preservation of physical evidence Source: (Richard Saferstein, 1981, Criminalistics—An introduction to Forensic Science, 2nd edition, Prentice Hall)

Anatomy of a Crime Lab Trace Evidence
Section Purpose Common Samples or Sample Sources Typical Methods Trace Evidence Examine small samples for unique characteristics Fibers, hair, flammables Chemical, physical and microscopic analytical methods. Controlled Substances Identify suspected illegal drugs for type and amount present Pills, powders, vials, syringes Chemical, physical analytics Forensic Biology Examine physiological fluids/stains for genetically determining factors: blood type, species Blood, saliva, other body fluids and tissues DNA analysis Forensic Alcohol Analysis for alcohol in DUI cases Blood, breath or urine samples from arrestees Automated gas chromatography, infrared spectrophotography Forensic Toxicology Analysis of blood and urine samples for presence of drugs or poisons DUI and controlled substance arrests Gas and thin layer chromatography Firearms Examination of firearms for class or individual characteristics Handguns, rifles, shotguns, shell casings, bullets Chemical and physical analysis, comparison light microscopy Fingerprints Examination of latent (not visible) fingerprint impressions for characterization and ID Any evidence with a surface that can accept a fingerprint impression Powders and chemicals used with light sources to visualize print Automated Fingerprint Retrieval Compares unknown prints from a crime scene to database of known prints Same as above Visually magnified comparisons and computer-aided scanning of evidence Questioned Documents Resolves questions concerning age, content or authenticity of documents Counterfeit documents, forged checks, anonymous letters, suicide notes Light, infrared and UV microscopy

Techniques are non-destructive or destructive Non-destructive techniques: Optical methods (naked eye, microscopy, photography) Spectroscopy (ultra-violet, infrared, X-ray fluorescence) Destructive techniques: Chemical reactions (screening tests for explosives, drugs, blood) Spectrometry (mass spectrometry) Analytical separation (TLC, GC, HPLC) in forensic science

High Performance Liquid Chromatography (HPLC) Gas Chromatography (GC) Mass Spectrometry (MS) Infrared Spectroscopy (IR)

Chromatography Basics
Separation method for biomolecules Outcome of a chromatography experiment is a CHROMATOGRAM Column chromatography Planar chromatography Open column

All chromatographic systems contain: Stationary phase Mobile phase Sample molecules (mixture for separation) Movement of molecules determined by balance between 2 forces: 1. Mobile phase 2. Stationary phase

1. Mobile phase (impelling force) Carries with it molecules for which it has affinity - favored by solubility (LC), volatility (GC) 2. Stationary phase (retarding force) Holds back molecules with which it interacts Balance between forces differs for different molecules Different mobilities, separation of components

a) Adsorption:

Chromatography

LC Mechanisms Adsorption (normal phase) Reversed Phase
Gel Permeation (size exclusion) Ion-exchange

HPLC Normal Phase Polar S-phase and nonpolar m-phase
Interaction with polar functional group on solute with s-phase surface Separation selectivity: relative strength of polar interaction of diff. solutes Solutes retention: spatial configuration, H-bonding ability with adsorbent Good for isomer sep. (fat+water soluble vitamins)

HPLC Reversed Phase Nonpolar S-phase, polar solvent with respect to sample Retention b/c hydrophobic interaction of nonpolar components of solutes and nonpolar S.P. S.P: hydrocarbons, waxy liquids, bonded hydrocarbons (C18, C8, C4) Solvents: polar aqueous-organic mixtures (methanol-water) Retention explained solvophobic theory S-phase, uniform layer nonpolar ligand Solute bind to s, reduce s surface area of solute exposed to m Solute is sorbed and retained b/c interaction with m not s Polar solvent, weak eluting solvent Nonpolar solvent, strong eluting

HPLC Reversed Phase Characteristics:
1. Sample types with a wide range of polarities and molecular weights can be separated 2. Rapidity of mobile phase column equilibration during methods development and gradient regeneration 3. General ease of use 4. Applicability to separation of ionic or ionizable compounds 5. The possibility of special selectivity such as structural or steric are achievable by specific mobile phase additives

HPLC Gel Permeation Preferred for high weight (> ) neutral molec Polymers, high MW proteins Separation b/c solute permeation into solvent filled pores within column packing Large: excluded from pores b/c physical size No retention Small: permeate greater portion of pores Retained In between: partial permeation Retention btw 2 extremes

HPLC Ion-exchange Ion exchanger surface
Cations, anions, water Cations, or anions chemically bond to insoluble matrix (organic and porous in nature) Chemical bound ions = fixed ions Ions of opposite charge = counter ions Pores have water and sufficient [counter ions] Exchanger electrically neutral Cations exchanger: fixed ions negative Anion exchanger: fixed ions positive Counter ions replaced by ions of same charge from external solution M+E- + A-↔ M+A- + E- Anion exchanger

Two Types of Ion Exchange Resins
Functional Group Counter-ion Anion Exchanger Diethylaminoethyl (DEAE) -O-CH2-CH2-N + H (CH2CH3)2 Cl - Cation Exchanger Carboxymethyl (CM) -O-CH2-COO - Na +

LC Mechanisms

Forensic LC Application
Gradient HPLC analysis of a smokeless powder Conditions: C-8 Column, 36-80% methanol/water gradient, 1 ml/min, UV detection at 230 nm wide variety of chemical components Different morphologies of smokeless powders

GC Instrument Components
1. Carrier gas Must be chemically inert Common nitrogen, helium, argon, and carbon dioxide Carrier gas system also contains a molecular sieve to remove water and other impurities 2. Sample injection port Sample should not be too large, and should be introduced onto the column as a "plug" of vapor - slow injection of large samples causes band broadening and loss of resolution Most common injection method is where a microsyringe is used to inject sample through a rubber septum into a flash vaporizer port at the head of the column Gas chromatography: specifically gas-liquid chromatography - involves a sample being vapourised and injected onto the head of the chromatographic column The sample is transported through the column by the flow of inert, gaseous mobile phase The column itself contains a liquid stationary phase which is adsorbed onto the surface of an inert solid

3. Columns Two types packed and capillary (also known as open tubular) Packed columns contain a finely divided, inert, solid support material coated with liquid s-phase Lower coast, less technical expertise Capillary columns have an internal diameter of a few tenths of a millimeter More efficient, improved detection, reduced flow rates, smaller samples Lower sample capacity, less forgiving of poor operator

Column Comparison

Packing Materials

4. Column temperature Optimum column temp dependant upon b.p of sample As a rule of thumb Temp. slightly above average b.p of sample results in an elution time of minutes Minimal temps give good resolution, but increase elution times If a sample has a wide boiling range, then temp programming Column temp is increased (either continuously or in steps) as separation proceeds Low [solute] in vapor phase (low temp), little solute move with m–phase high [solute] in vapor phase (high temp), all solute removed from s-phase Separation b/c interaction with s-phase, little separation happen

5. Detectors Many detectors which can be used in GC Different detectors will give different types of selectivity A non-selective detector responds to all compounds except carrier gas A selective detector responds to a range of compounds with a common physical or chemical property A specific detector responds to a single chemical compound

Detectors can also be grouped into concentration dependant detectors and mass flow dependant detectors Signal from a concentration dependant detector is related to concentration of solute in detector Mass flow dependant detectors usually destroy sample Signal is related to rate at which solute molecules enter detector Response of a mass flow dependant detector is unaffected by make-up gas

GC/MS GC separates mixtures of volatile and semi-volatile organic compounds into individual components Sample is flash vaporized, and molecules are swept onto the GC column with an inert carrier gas Separation occurs as components partition themselves btw S.P. on inner wall of column and M.P. (carrier gas) Time it takes for given molecule to traverse entire length of column is known as retention time Retention time is a function Chemical structure of component Column type Temp profile it was subjected to during chromatography exp. Relative affinity of compound for the S and M phases MS then detects components that elute from the end of the GC column

Forensic GC/MS Application
1. Cocaine in hair: First GC/MS to detect cocaine in hair in 1987 Hair samples from suspected drug abusers analyzed for cocaine Cocaine, not Benzoylecgonine primary analyte in hair Metabolites BZE and ecgonine methyl ester present in low and variable concentrations Detected in hair for months after administration

2. Drug Metabolite in blood Comatose patient suspected overdose of prescription drug glutethimide (DoridenTM) B/c empty bottle where patient found Gas chromatogram obtained of blood plasma extract Retention times for peak 1 correspond to glutethimide Second peak Possibility of another drug considered Retention times for peak 2 did not match any known drug of abuse

GC/MS for peak 2 ID MS confirmed peak 1 for glutethimide MS shows that peak 2 has m/z = 233 Differs from molecular ion of glutethimide by 16 mass units Indicate incorporation of oxygen atoms into glutethimide molecule So, 4-hydroxy metabolite of glutethimide OH

GC or LC

GC or LC?

Chromatography Compounds often cannot be analyzed by a particular method B/c are not in a form amenable to analytical technique Examples of this problem are non-volatile compounds for GC and insoluble compounds for HPLC Many compounds that are not stable under conditions of technique (Di- and tri- basic acids as well as hydroxy acids) Derivatization procedures: Modifies chemical structure of compound May be analyzed by GC

Dynamic Headspace Analysis (HSA)
Sampling technique Direct determination of volatile constituents in liquid or solid samples By analyzing vapor phase that is in thermodynamic equilibrium with the sample in closed system Primarily for analysis of volatile compounds in matrices resent in trace amounts and could not be directly injected into GC Polymers Alcohol Drugs Cosmetics Food and beverages Environmental samples Biological specimens not suitable for direct injection Method: Sample is placed in a closed chamber Heated to a specified temp. Atmosphere surrounding sample is continuously swept with stream of dry inert gas Components that outgas from sample are collected and analyzed by GC/MS

Pyrolysis Specialized sample introduction technique
Rapid heating for decomposition Normally used to analyze non-volatile organic compounds Wood, paper or polymers, by GC/MS Method: Sample heated rapidly to 750°C or higher to thermally decompose it High temperature break polymer backbone, forming smaller, more volatile fragments Fragments examined for structure of polymer chain Used frequently to examine materials for the presence of additives Plasticizers Anti-oxidants UV-stabilizers, or sizing treatments applied to cloth samples

Forensic applications of GC and HPLC Drunk driver blood and urine samples Analysis of poisons in autopsy samples Analysis of inks used in forged banknotes

Detects the components that elute from end of GC column
MS Detects the components that elute from end of GC column

MS Energetic electrons bombard component molecs. ionizing some of them
Ionization process produce fragment ions which often provide structural information about molec. Ions then accelerated by electric field and enter mass analyzer where separated according to their mass-to-charge (m/z) ratios Plotting abundance of ions as function of (m/z) ratio to generate mass spectrum Mass spectrum: Unique “fingerprint” Allow identification of unknown compounds “Fingerprint” compared with database Over 107,000 unique chemical compounds

MS Sometimes database no help b/c:
A) Mass spectrum contains unique chemical information Abundant, unusual fragment ions - no compound in database is even close to matching it B) Mass spectrum is not very unique at all - matches with thousand other compounds Best that can be done is to place it within a chemical class

Fourier Transform Infrared Spectroscopy
Study of interaction of electromagnetic radiation with matter Method: Sample is inserted into the instrument Infrared light is absorbed This spectrum is compared to a known spectrum in a computer library

Fingerprint

Fingerprints History 3000 years ago 1880 1924
Use for identification goes back to ancient Chinese Sign legal papers 1880 Henry Fauld Suggested use of friction ridges Identify criminals 1924 FBI identification division established Accepted that credit given to Henry Fauld and Sir Edward Richard Henry for use as means of identification

Fingerprint Anatomy Skin Papillae Epidermal outer layer
Dermal inner layer Between is papillae Papillae Contain friction ridge structures Responsible for our one-of-a-kind fingerprint pattern Ridge develop during fetal stage and remain unchanged during life

Fingerprint Anatomy Sweat glands Located in dermis
Extend their ducts up through epidermis Release perspiration, oils, other materials through sweat pores Oils…etc leave an identifiable residue conforming to the pattern of an individual fingerprints

Fingerprint Types 3 Types of Fingerprints Visible prints
Made visible by virtue of background or surface on which they are made Plastic prints Made by impressions onto a soft material Latent prints Invisible prints that need to be made visible By mechanical or chemical means

Latent Fingerprints Most common techniques used to find latent or hidden fingerprints: 1. Dusting with Carbon powder White or light colored surfaces 2. Dusting with Aluminum Powder Hard or dark colored surfaces Mirrors and metal surfaces 3. Use of Cyanoacrylate (super-glue) fuming 4. Use of Iodine fuming techniques 5. Use of Ninhydrin

Iodine Fuming Oldest of chemical methods Solid iodine sublimes
Becomes vapor without becoming a liquid at R.T. Object placed in chamber has some crystals of iodine placed in it Any fingerprints on object will appear as brownish prints On greasy surfaces iodine fume absorbed at different rates by different fatty or oily residues Print temporary, will soon fade Photographed immediately Fixed by spraying with starch solution Give a blue print which will last longer

Ninhydrin -spraying with chemical ninhydrin
-which reacts with amino acids present in the skin secretions -give purple prints ninhydrin/zinc chloride/laser

Superglue Active ingredient in superglues is cyanoacrylate ester
Drops superglue heated When vapors of these compounds come into contact with fingerprints (a.a., fatty acids, moister) Molecules of cyanoacrylate attach to print and polymerize Visible prints produced are white To improve their delectability Often treated with a fluorescent dye, such as Rhodamine 6G, before being photographed under an special light source or a laser Best on nonporous-metal, glass, plastic

These fingerprint pattern composed of many individual friction ridges
Fingerprint Patterns Loop (65%) Radial Ulnar Whorls (30%) Plain Central Double loop Accidental Arch (5%) Tented These fingerprint pattern composed of many individual friction ridges

Loop Pattern (65%) Loop pattern
One or more ridges entering from one side, curving, then leaving the other side Always develop ridges that diverge to form a delta All loops must have one delta

Loop Pattern (65%) Radial loop Ulnar loop
Loop pattern on a fingerprint card that opens toward the thumb Ulnar loop Loop pattern on a fingerprint card that opens opposite the thumb

Whorls Pattern (30%) Friction ridges that have a minimum of two deltas
4 whorl sub-groups Plain Two deltas and complete ridge circuit Central One of the two deltas is stretched out Double loop Two loops and two deltas Accidental Anything other than above with 2 deltas

Arch (5%) Arch 2 arch sub-groups
Friction ridges that enter from one side of the finger and cross to the other side while rising upward in the middle 2 arch sub-groups Plain Mild bulging Tented Pole in the middle

Individual Ridge Characteristic
Five ridge characteristics

Blood Bloodstain or spatter patterns:
Explain a lot about positions and movements during crime Can provide information Who struck first In what manner How many times Provide: 1. Direction droplet was traveling 2. Impact angle Impact angle is angles at which blood droplet struck a horizontal surface such as floor

Blood Blood spatter Shapes: Round to oval shape Round:
Blood drops from directly above depend on surface texture Elliptical or oval: Some impact on droplet Ex: from a gunshot or any penetrating wounding agent Long axis ellipse indicate blood direction that has been traveled from Elliptical shape of bloodstains becomes longer and sharper as speed increases Thicker side of elliptical stain - blood has traveled Thinner side with tail looks - origin of blood droplet was coming from

Blood Since lot blood spatter in crime scene
Investigator improve view of blood flight paths Draws lines with strings at crime scene Use CAD software Surface: Harder surface Less splatter will result Extremely important to duplicate surface in controlled test Hard and smooth Blood usually breaks apart upon the impact Causes smaller droplets Smaller droplets continue to move in the same direction as the original droplet

Blood Equation in diagram (impact angle):
Calculated with width and length of the bloodstain Combined with point of convergence Origin in three-dimensional space is located Point of convergence: Location of blood source can be determined by drawing lines from the various blood droplets to point where they intersect Area of convergence may be established at scene with measurement of angles by use of strings

Blood Kastle-Meyer color test Hematest® tablet Luminol test
Mixture of phenolphthalein and hydrogen peroxide Hemoglobin will cause formation of a deep pink color if blood is present Hematest® tablet Reacts with heme group in blood causing a blue-green color Luminol test Reaction with blood to produce light

Luminol-Blood Detector
Mixture of luminol and hydrogen peroxide Sprayed at crime scene Energy produced by reaction excites electrons Electrons give off their energy as light Photon released 425nm

Luminol-Blood Detector
Luminol can detect blood at 1ppm Reveal old stains not visible to the naked eye

DNA Fingerprinting

DNA Analysis DNA first used in criminal trial in 1987 to convict a rapist in Britain DNA samples can be identified with an error of less than one in ten million Nucleotide consists Sugar molecule (deoxyribose in DNA) Attached to phosphate and base unit Acidic nature of phosphates led to DNA being called Deoxyribonucleic acid Occurs as 2 long chains that are connected by H-bonding btw base pairs Base pairs are: Adenine and thymine (AT or TA) Cytosine and guanine (CG or GC)

DNA Fingerprinting Process where genomic DNA of organism is analyzed
Done by Examining several specific variable DNA sequences Located throughout genome Humans 2 DNA types: Cellular chromosomal Packed in 23 sets in nucleus of cell From both parents Mitochondrial In mitochondria (E producing organelles) Maternally only (both males and female children) DNA carries 2 forms of information Genetic coding and non-coding information Positive identification of DNA profile By comparison with other DNA profiles from known individuals

Electrophoresis Biological molec: amino acids, peptides, proteins, nucleotides, nucleic acids, have ionisable groups

DNA Fingerprinting RFLP PCR
Technique for analyzing variable lengths of DNA fragments that result from digesting DNA sample with special kind of enzyme Enzyme, a restriction endonuclease Cuts DNA at specific sequence pattern know as restriction endonuclease recognition site Presence or absence of certain recognition sites in DNA sample Generates variable lengths of DNA fragments, which are separated using gel electrophoresis Then hybridized with DNA probes that bind to complementary DNA sequence in sample Facilitated by southern blot analysis Need lots of DNA PCR make millions of exact copies of DNA from a biological sample

Restriction Fragment Length Polymorphic

Southern Blot Technique

Paternity Case

Other DNA Technologies in Forensic
STR Analysis Mitochondrial DNA Analysis Y-Chromosome Analysis

STR Analysis Short tandem repeat technology:
Used to evaluate specific regions (loci) within nuclear DNA Variability in STR regions used to distinguish one DNA profile from another Federal Bureau of Investigation (FBI) uses standard set of 13 specific STR regions for CODIS CODIS is software program: Operates local state and national databases of DNA profiles from Convicted offenders unsolved crime scene evidence and missing persons Odds 2 individuals will have same 13-loci DNA profile is about one in one billion

mtDNA Analysis mtDNA used to examine DNA from samples that cannot be analyzed by RFLP or STR Uses DNA extracted from a mitochondrion For cases that have gone unsolved for many years All mothers have same mtDNA as children Mitochondria of each new embryo comes from mother's egg cell Father's sperm contributes only nuclear DNA

Y-Chromosome Analysis
Y-chromosome passed directly from father to son Analysis of genetic markers on Y chromosome useful for Tracing relationships among males Analyzing biological evidence involving multiple male contributors

Hair Techniques used in analyzing hair and fiber
Grows about 0.5 mm per day or 1 centimeter per month Approximately one half inch per month

Morphology/Structure of Hair

Morphology: Cuticle Protective coating made of overlapping scales, produce a characteristic pattern Scales always point toward tip of hair Not useful in individualizing human hair Can be used for species identification

Morphology: Cortex Made of spindle-shaped cells aligned in regular array Parallel to length of hair Embedded with pigment granules Give hair its color Color, shape, distribution of granules provide points for forensic comparison Cortex examination Suspended in liquid with refractive index similar to that of hair

Morphology: Medulla Canal like structure of cells that runs through center of cortex

Medullary Index Measure of diameter of medulla relative to diameter of hair shaft Usually expressed as fraction Humans: Medullary index < 1/3 Animals: Medullary index > 1/2

Medulla of Different Species

Forensic Analysis of Medulla
Presence of medulla varies, even hair to hair Human head hairs: Generally no medulla or Fragmented ones; except Asian race - medulla usually continuous Most animals: Medulla that is continuous or Interrupted Shape of medulla can help identify a species

Identification and Comparison of Hair
Morphological Characteristics do not allow individualization of a human hair to any single head or body Collected hair with an adequate number of standards/references Provide strong circumstantial evidence Scale structure, medullary index, and medullary shape are most often used for hair comparison Evidential value lies with degree of probability associated with a questioned hair and an particular individual 11% of all morphological hair matches are generally found to be none matches Has to be confirmed by DNA comparisons

Hair- Racial Origin Mongoloid (Asian) Caucasian Negroid (African)
Continuous medullae Dense pigment distributed evenly cross section round Hair shaft coarse and straight Caucasian Even distribution of pigment in cortex Straight to wavy fragmented medullae or absent of medullae cross section oval/round, fine to coarse pigment Negroid (African) Uneven distributed pigment Curly Variations in diameter Fragmented or absent of medullae Asian Caucasian African

Microscopy Two matching hairs identified by the comparison microscope

Hair-Age Age cannot be determined definitively by a microscopic examination Microscopic appearance of certain human hairs Ex: infants and elderly individuals, may provide a general indication of age Infants: Generally finer and less distinctive in microscopic appearance As individuals age: Hair can undergo pigment loss, changes in configuration of hair shaft to become much finer and more variable in diameter

Hair-Root Human hair grows 3 developmental stages:
Anagen, catagen, and telogen phase Initial growth phase: Hair follicle is actively producing hair Phase may last 6 years Root is flame like in appearance When pulled this root may contain a follicular tag Rich source of DNA Anagen hair root Root with follicular tag

Firearms

Terminologies Barrel: metal tube bullet is fired through it
Bore: inside of barrel Caliber: diameter of bore expressed in inch (.22 cal) or millimeters (9mm) Cartridge: also called a "round". Made up of a case, primer, powder, and bullet Chamber: portion holds the cartridge ready for firing Muzzle: end of the barrel out of which bullet comes Double-action revolver

Firearms Double-action revolver

Firearms Detection of particles produced when firearm is discharged
No 2 firearms, even of same make and model produce same unique marks on fired bullets and cartridge cases Surface characteristics within firearm cannot be exactly reproduced in other one b/c Manufacturing processes Use Abuse Firearms do not change much over time Firearms recovered months or years after shooting identified as having fired specific bullet or cartridge case Tests conducted found Even after firing several hundred rounds through firearm last bullet fired could still be identified to the first

Firearms All firearms case identification start with preliminary examinations of evidence for similar class characteristics Class characteristics: Intentional or design characteristics that would be common to particular group or family of items Example: Several no. 2 pencils in box are yellow and have pink erasers Color and eraser type is common class characteristic to all of pencils

Firearms Firearms ID and ammunition it is not simple
Class characteristics that relate to bullets fired from them includes Caliber of firearm Rifling pattern contained in barrel of firearm Cartridges and Cartridge cases-examined for class similarities

Firearms When similar class characteristics are identified
Examinations goes to final stage to find "match" in individual characteristics Individual characteristics: Marks produced by random imperfections or irregularities of tool surfaces Produced incidental to manufacture and/or caused by use corrosion or damage Unique to that tool and distinguish it from all other tools Transfer of individual characteristics from a firearm to ammunition components passing through it Makes firearms identification possible

Bullet ID Bullets: projectile Round-nose - end of bullet is blunted
Hollow-point- hole in bullet creates expansion when target is struck, creating more damage Jacketed- soft lead is surrounded by another metal, usually copper, allows bullet to penetrate a target more easily Wadcutter - front of bullet is flattened Semi-wadcutter- Intermediate btw round-nose and wadcutter

Bullet ID 1. Examination to see if of caliber that could have been fired from submitted firearm 2. Examination to determine if rifling impressions pattern found on bullet match pattern of rifling contained in barrel of questioned firearm 3. If class characteristics agree 4. Try to make a positive match btw individual characteristics that may have transferred to bullet from barrel Within rifling impressions on bullet, microscopic scratches can be found

Bullet ID Bullet range firing checked:
Close range: Less than 1 m Bullet hole greater than bullet itself Scorching near wound on clothing Long range: Greater than 1m Small/neat wound Imperfections in surface of interior of barrel leave striations on projectiles Striations have potential to be consistently reproduced in unique pattern on every bullet that passes down barrel of firearm

Bullet ID Bullet: Base will contain irregular dimples marking pressure delivered there in its acceleration Sides will bear markings of barrel interior rifling Spiral lines contain microscopic imperfections of gun from which it was fired Specific as fingerprint Nose carries information about target give clue to injury rendered

Bullet ID

Bullet ID Ballistic

Examination of Bullets in Crime labs
Class: type of caliber and rifling Rifling pattern may turn to right or left, with given rate of twist Number and depth of grooves Individual characteristics: determine if specific gun was used Based on imperfections in barrel, particularly muzzle (impart specific markings to fired bullets) Markings present lead to "determinative" identification Smaller caliber weapons (.22) yield fewer reproducible characteristics in fired bullets than weapons of larger caliber (.45) Patterns of Bullet markings Two sets of bullets of same class compared to show how difficult this can be when bullet deformation is present

Examination of Bullets in Crime labs
Bullets examined using 12 parameters: Identification number Manufacturer Weight Diameter Cartridge Base design Length of bearing surface Color Shape Parameters aid in narrowing search for suspected weapons Results of comparison identification, test fired and recovered bullets can: (1) Be related to same weapon (2) Be unrelated to same weapon (3) Not be compared with this type of examination Conclusions should not be based upon probabilities in test firing

Ballistic Term refers to science of travel of projectile in flight
Flight path of bullet includes: Internal-Travel down the barrel External-Path through the air Terminal-Path through a target

Internal-Initial Ballistics (Within Gun)
Bullets fired from rifle have more energy than similar bullets from handgun More powder in rifle cartridges Bullet chambers designed to withstand greater pressures (70,000 psi vs. 40,000 psi for handgun chamber) Difficult to measure forces within gun barrel Easily measured parameter is velocity of bullet exiting barrel (muzzle velocity) Bullet travel through gun barrel Characterized by increasing acceleration as expanding gases push on it Up to a point the longer the barrel greater the acceleration

External Ballistics (Gun to Target)
Refers to behavior of bullet after it exits barrel and before it hits target Use of ballistics tables or ballistics software based on G1 drag model are the most common method used to work with external ballistics Drag: force that resists movement of a solid object through fluid (liquid or gas) Several formulae, simplest is: Kinetic Energy (KE) = 1/2 MV2 Velocity (V) feet/second Mass (M) pounds Motion of bullet depends on: 1. Ballistic coefficient 2. Drag

Ballistic coefficient (BC)
Will determine KE delivered to target as air resistance is encountered BC = SD/ I SD= sectional density of bullet Bullet mass ÷ square of its diameter I = form factor for bullet shape I decreases with increasing pointedness of bullet Sphere have highest I value

Drag (D) Forward motion of bullet also affected by drag
Drag (D) = f(v/a)k&pd2v2 f(v/a) = coefficient= ratio of velocity of bullet/velocity of sound in medium through which it travels k = constant for shape of bullet &= constant for yaw (deviation from linear flight) p = medium density (tissue density is >800 times that of air) D= diameter bullet caliber v = velocity More drag when greater v, greater caliber, or denser tissue Degree to which bullet is slowed by drag called retardation (r) r = D/M D=function of velocity, bullet of given mass (M), greater velocity, greater retardation D=influenced by bullet spin, faster spin, less likely bullet will "yaw" or turn sideways and tumble

Formulae Meaning Designing Cartridges & Bullets?
Given that: Cartridge can be only so large to fit in chamber Steel of chamber can handle only so much pressure from increasing amount of gunpowder KE for any given weapon is increased more easily by increasing bullet mass V2 increase KE much more, very difficult to increase velocity, which is dependent on amount of gunpowder burned Only so much gunpowder can be burned efficiently in cartridge Cartridges designed for hunting big game animals use very large bullets

Terminal Ballistics (Hitting the Target)
Tumbling has a lot to do with injury pattern of bullet on target Short, high velocity bullet begins tumbling more rapidly in tissue Causes more tissue to be displaced and imparts more of KE to target Longer, heavier bullet might have more KE at longer range when hits target Penetrate so well that it exits target with much of its KE remaining Bullet with a low KE can cause significant tissue damage If designed to give up all of KE into target Target is at short range (as with handguns)

Gunshot Residue Residue cloud produced by discharge of gun
Residue emitted from muzzle, ejection ports, cylindrical gaps and other vents This then deposited on surrounding area Ex: hands, clothes, and hair of the firer

Gunshot Residue Time-lapsed image showing a bullet exiting from barrel
Streaks of burning gunpowder, smoke, and unburned particulate can be seen exiting barrel as well

Composition of GSR Residue may be found:
Skin or clothing of person who fired gun Entrance wound of a victim Other target materials at the scene Discharge of firearm, particularly a revolver, can deposit residues even to persons at close proximity Interpretations as to who fired weapon should be made with caution

Composition of GSR Major primer elements are Pb, Ba, Sb
Usually, all 3 present Less common elements: Al, S, Sn, Ca, K, Cl, or Si Mercury-fulminant based primer found in ammunition manufactured in Eastern Europe and used in Middle East Primer elements easier to detect in residues B/c do not get as hot as powder and compounds (not just elements) may be detectable Primer residues Adhere to fired bullets and gradually ablate through bullet path Found in targets or wounds at considerable distance from muzzle (up to 200 meters)

Composition of GSR Cartridge case, bullet, bullet coating, and metal jacket also contain specific elements that can be detected Cartridge cases made of brass (70% copper and 30% zinc) Few have nickel coating Primer cases are of similar composition (Cu-Zn) Bullet cores Pb and Sb, very few have ferrous alloy core Bullet jackets usually brass (90% copper with 10% zinc) some are ferrous alloy and some Al Some bullet coatings contain nickel Modern gunpowder, or "smokeless" powder contain up to 23 organic compounds Nitrocellulose always present with other compounds containing nitrate or nitrogen One of these compounds Diphenylamine (used as stabilizer in powder) detected using reagents containing sulfuric acid

Composition of GSR Modern gun powders described as:
“Single-base“-basic ingredient is nitrocellulose “Double-base“-additionally 1 to 40% nitroglycerine added Differentiated using mass spectrometer Physical examination of scene or body for evidence of gunshot residue Careful b/c lead residues may mimic gunshot residue Lead residues may be found up to 30 feet from muzzle always present on opposite side of penetrated target Amount of residue deposited tends to decrease with increasing range of fire Actual deposits can be highly variable for ranges up to 20 cm

Detection of GSR Major methods for detection of primer residues:
Neutron activation analysis (NAA) Atomic absorption spectrophotometry (AAS) Scanning electron microscopy (SEM) Samples must be obtained from skin surfaces of victim at scene Delay in obtaining residues, movement, or washing of body prior to autopsy Destroy gunshot residues SEM Best method Residue collection is simple and easily carried out in field Large particles of partially burned powder and spheres of residue can be distinguished from contaminant materials

Detection of GSR Scanning Electron Micrograph of GSR

Detection of GSR An X-ray analyzer can be beamed directly on particles
Energy dispersive pattern (EDX) generated Give elemental of particles Computer program speed up search for GSR particles by SEM Diagram of the SEM-EDX pattern of GSR

Detection of GSR SEM useful for examination of bullets
Embedded materials from target such as bone fragments may aid in reconstruction of scene SEM: study tool marks made by firing pin impressions in primers of spent cartridges Useful to determine which gun was used to fire cartridge SEM reveal all surface detail in impression 50% of shotgun impressions positively identified 75% of rifle impressions positively identified Basis of 4 or more individual characteristics Given similar class characteristics Difficult to both find and determine nature of gunshot wounds in decomposed body Determination of range particularly difficult

Other Examinations Question if victim was holding firearm arises in investigation Latent fingerprints may be detectable on cartridges and expended shell casings Increased temp and low humidity decrease persistence of fingerprints Each firearm sold (other than black powder weapons) has manufacturer's serial number stamped into it to identify weapon Registration of firearms provides way of tracing gun ownership However, attempts may be made to obliterate registration numbers by grinding or filing metal GC Identify gun oils in targets Very sensitive, even with stored specimens

Glass & Soil

Glass Components Network Formation Fluxes – Softeners
SiO2, B2O3, P2O5, GeO2, V2O5, As2O3, Sb2O5 Fluxes – Softeners Na2O, K2O, LiO, Al2O3, B2O3, Cs2O Stabilizers – Provide chemical resistance CaO, MgO, Al2O3, PbO, SrO, BaO, ZnO, ZrO

Major Types Soda lime silicate glass Borosilicate glass
SiO2 + Na2O / K2O + CaO / Al2O3 / MgO Flat glass, container glass, electric light bulbs Borosilicate glass > 5% B2O3 (in place of Na2O) Lab glassware, thermometers, cookware, sealed-beam headlights Aluminosilicate glass Higher percentage of aluminum Useful at higher temperatures than borosilicate Aluminoborosilicate – 50:50 Al/B Labware, cookware, and glass fibers Lead alkali silicate (leaded glass) Up to 80% PbO Low softening temp, high refractive index “Crystal” tableware

Glass Useful evidence in wide variety of cases
Hit-and-run Burglaries Assault Hard, brittle, amorphous substance Composed of silicon oxides mixed with various metal oxides Metal oxides include those of Na, Ca, K, Mg, Li, Ba and B Act to modify properties of glass Co, Cr, Mn and Ni are used to alter color of glass

Glass Density and RI: compare glass found at crime scene with glass fragments found on suspect Both require significant statistical treatment to determine likelihood of 2 samples originating from same source Elemental analysis: Methods such as SEM/X-ray dispersive spectroscopy Quantitative methods: Determine exact proportions of each element Modern manufacturing techniques and homogenous nature of glass produced positive identification can be made

Glass & Soil Many inorganic compounds are analyzed as evidence by forensic chemist Analysis of inorganic compounds present in sample, their specific proportions can offer positive identification Ex: glass and soil Inorganic compounds are important Their composition is rarely altered by bacterial action or time

Soil Soil important when moved accidentally or deliberately, during criminal activity Number of soil types on Earth is not known Complexity b/c Mixture of inorganic materials and organic residues Influenced by climate, seasons, geographical location and geological evolution Inorganic component approximately 95-99% of composition of soil Physical examinations (particle size) Many methods developed for forensic examination of soil Most adapted from geology, soil science, chemistry, related fields

Soil Three major types Clay: Loam: Sandy: Very fine particles
Holds water well Loam: Particle size vary (btw clay and sand) Retain some water Contain more humus (plant and animal remains) than other types Sandy: Holds very little water Crumbles easily

Soil Methods generally used in analysis of soil
Combination of methods will identify minerals present and their proportions Information used to locate original location of soil: 1. General examination: Stereomicroscope and microscope Foreign material such as fibers and glass removed Frequency of each crystal type determined 2. pH measurement: Soil and distilled water mixture centrifuged until solution clear Solution then tested for pH

Soil Interpretation of soil evidence is challenge
3. Size distribution of particles: Sample is passed through a nest of sieves Weight of each fraction is determined 4. Density distribution of particles: Density gradient column is used to separate known weight samples that have been previously sieved 5. Instrumental analyses: Ex: emission spectroscopy, atomic absorption spectroscopy, neutron activation analysis, X-ray fluorescence, X-ray diffraction, infrared spectroscopy, pyrolysis gas chromatography and laser Raman spectroscopy Interpretation of soil evidence is challenge Usual receptor surfaces (shoe soles, tires, floors) in contact with soil samples from different sources Soil evidence is often a mixture of soils

Stereomicroscope Used for examining objects, statues, or sculptures that are unable to be placed on a stage of a microscope Examination done at any angle and axes with excellent field depth and contrast richness

Measure of the degree to which the glass bends light
Index of Refraction Incident angle θi Measure of the degree to which the glass bends light symbol n: θr Refraction angle Ray of light that passes from air to glass Change the direction it travels Path is bent Amount of bending depends on nature of glass and wavelength of light used

Index of Refraction Light bends according to Snell's law
n1 sin(θ1) = n2 sin(θ2) n1: refractive index of medium light is leaving sin(θ1): incident angle between light ray and normal to medium to medium interface n2: refractive index of medium light is entering sin(θ2): refractive angle between light ray and normal to medium to medium interface

Determining Refractive Index
Liquid Immersion When glass and liquid have same refractive index, particle will be (nearly) invisible Becke Line = Bright halo around particle When incident of refraction of and surrounding medium is different Microscope is defocused Becke Line

Becke Line nglass >nmedium nmedium = 1.525 nglass < nmedium
Glass has higher refractive index Becke line seen inside Rays converge Glass has lower refractive index Becke line seen outside Rays diverge

Determining Refractive Index
Glass RI: – 1.560 Immersion Liquids: Silicone Oils Organic Compounds Cyclohexanone m-xylene Methylsalicylate Benzaldehyde Benzyl benzoate Different types of glass Compared and distinguished by referring to unique refractive index values

Glass Liquid RI Glass Water 1.333 Vitreous silica 1.458 Olive oil
1.467 Headlight Glycerin 1.473 Window Castor oil 1.82 Bottle Clove oil 1.543 Optical Bromobenzene 1.560 Quartz Bromoform 1.597 Lead Cinnamon oil 1.619 Diamond 2.419

Glass Dispersion (V) – Change in Refractive Index with wavelength
Chemical Composition: SEM with EDX Neutron Activation Analysis X-Ray Fluorescence

Glass Density Displacement methods Glass vary widely Type of Glass
window headlight pyrex lead glass porcelain

Glass Fragments transferred from anything made of glass which breaks, to whoever or whatever was responsible Variation in manufacture of glass allows considerable discrimination even with tiny fragments 60% of cases involving glass provided some positive evidence 40% of these cases this evidence was strong Depending on circumstances Findings can also refute allegation that a person was involved in a crime

Glass Pane of broken glass:
Fragments can be showered on hair, clothing and footwear of people in close proximity At least 1.5 and possibly up to 3m away Number of fragments transferred decreases rapidly with distance from breaking pane Fragments can also be acquired By climbing through broken window or treading on pieces of broken glass Fragments recovered from hair and clothing range mm Most glass is lost fairly rapidly - depending on activity of wearer and texture of their clothing Woolen jumper tend to retain glass fragments far longer than leather jacket Fragments can be trapped pockets, crevices on shoe uppers, remain embedded in shoe soles for long time

Discriminating Btw Different Glasses
Forensic scientists interested in freshly broken glass (clean and sharp-edged fragments) recovered from hair combings or surfaces of garments Glass that been broken and/or acquired recently Compared and contrasted with reference samples of broken glass From scene, by refractive index, density, measurements and chemical analysis tests

RI very accurate test distinguish btw large number of different glasses differ in RI from reference glass sample Could not originated from same piece of glass Chemical analysis provides detailed information about chemical makeup From sand and other materials used in its manufacture Chemical analysis used to distinguish btw glass samples with same RI but different chemical composition

Glass fragments surfaces Microscopically examined for evidence of method of manufacture and type of object from which they came Flat glass and patterned glass Both from window pane Curved glass Drinking glass or bottle Further tests performed to see if source was of toughened glass Forming small cubes when broken Found in some car windows and in door and window glazing

Interpretation 1. Recovered fragments match reference sample
Both in RI and chemical composition 2. Discover how rare or otherwise glass might be Scientist consult computer database containing combined results of RI and chemical analysis for each and every reference glass sample examined by lab Show how many times particular type of glass is encountered

Comparison Microscope
Paint samples from suspect and from a crime scene Match

IR Compare characteristic absorption bands
Peaks on graph of 2 different paint samples can be compared

Forensic Examination Paint evidence is frequently encountered in hit-and-run and burglary cases Most examinations consist in comparing 2 or more paints to find their origin Color, make and model of a vehicle can be determined

Paint Characteristics
Spread on surface: Dry to hard film of pigments and additives suspended in binder Binder provides support medium for pigments and additives Modern automotive finishing consists of at least 4 coatings: Electrocoat Primer Primer Surface Basecoat Clearcoat

Paint Characteristics
Electrocoat Primer First layer Electrodeposited: Metal body is electrically charged Immersed in bath containing oppositely charged paint particles Particles attract to metal surface, neutralized, baked into coherent, tough film Provides corrosion resistance—color from black to grey Primer Surface Second layer Smoothes out and hides any seams on car—color pigments used to minimize contrast btw primer and topcoats Basecoat Third layer Provides basic color and appearance of car Clearcoat Final coat Provides great appearance (glossiness) and protection for car

Techniques in Paint Examination
Questioned and known specimens Compared side by side under a stereomicroscope Color Surface texture Color layer sequence

Paint Examination Layer sequence is important evidence
Forensic scientists try to match layers with respect to number and sequence of color Layer structure alone will not provide enough information to be individualized to single source Chemical analysis of paint’s pigments and binder composition provides further points of comparison GC determine chemical make-up of binder material IR determine binder composition of paint Odds against crime-scene paint originating from another randomly chosen vehicle approximately 33,000 to one

Spectroscopy to ID paint

Natural/Plant Cotton fibers are plant fibers most commonly used in textile materials Cotton has ribbon-like shape with twists at regular intervals Fiber length degree of twist contribute to diversity of these fibers Processing techniques and color applications also influence value of cotton fiber identifications Cotton

Natural/Animal Most animal fiber used in production of textile materials is wool Most common wool fibers from sheep End use of sheep's wool dictates fineness or coarseness of woolen fibers: Finer woolen fibers: production of clothing Coarser fibers: carpet Fiber diameter and degree of scale protrusion of fibers are other important characteristics Woolen fibers from other animals also used Camel, alpaca, cashmere, mohair Wool

ManMade >1/2 of all fibers used in production of textile are man-made Some fibers originate from natural materials (cotton or wood) Others from synthetic materials Polyester and nylon fibers are most common man-made, then acrylics, rayons, and acetates Amount of production of particular man-made fiber and its end use influence degree of rarity of given fiber Shape of man-made fiber can determine value placed on that fiber Cross section of man-made fiber is manufacturer specific: Some cross sections more common than others Some shapes produced for short period of time Unusual cross sections in examination add significance to fiber association

Cross section-manmade fiber
Regenerated Fibers Made from regenerated cellulose (wood or cotton pulp) Synthetic Fibers Currently manufactured Made from synthetic chemicals called polymers Nylons, polyesters, and acrylics Cross section-nylon carpet fibers seen with SEM Cross section-manmade fiber

ManMade Synthetic fiber: Generally smooth Can contain grooves
Along fibers from manufacturers process Pushing or pulling through very fine holes gives characteristic grooves

Factors that Determine Fiber Value
Fiber Color Fiber number Fiber location Fabric type Fiber Transfer and Persistence Nature of Contact Multiple Fiber Associations

Fiber Color Influences value for identification
Several dyes used give fiber desired color Individual fibers can be colored prior to spun into yarns Yarns can be dyed, fabrics made from them can be dyed Color can be applied to surface of fabric, as found in printed fabrics How color is applied and absorbed along length of fiber are important comparison characteristics Color-fading and discoloration give increased value to fiber association

Fiber Fiber Number Fiber Location
Fiber # on victim clothing identified as matching clothing of suspect is important in determining actual contact More fibers #, more likely contact actually occurred btw these individuals Fiber Location Location affects value placed on particular fiber association Location on different areas of body or on specific items at crime influences significance of fiber association

Fiber/Fabric Type Construction affects # and types fibers transferred during contact Tightly woven or knitted fabrics Shed less often than loosely knit or woven fabrics Fabrics composed of filament yarns Shed less than fabrics composed of spun yarns Fabric age affects degree of fiber transfers Newer fabrics Shed more readily b/c of abundance of loosely adhering fibers on surface of fabric Some worn fabrics Damaged areas that easily shed fibers Damage to fabric during physical contact greatly increases the likelihood of fiber transfer

Fiber Transfer and Persistence
Textile fibers are transferred to surface of fabric Direct transfer (primary transfer) or Indirect transfer (secondary transfer) Likelihood of transfer depends on Types of fabric involved in contact Nature of contact Duration of contact Studies show that transferred fibers are lost quickly depending on Types of fabrics involved Movement of clothing after contact Ex, clothing of homicide victim would tend to retain transferred fibers for longer time b/c victim is not moving

Fiber Nature of Contact Multiple Fiber Associations
Type of physical contact btw suspect and victim can determine # of fibers transferred and value Violent physical contact of an extended duration result in numerous fiber transfers Multiple Fiber Associations Multiple fiber types found on different items of clothing or fabric From suspect, victim, and crime increase likelihood that contact happened btw these individuals and scene Each associated fiber type considered to be an independent event Multiple associations undermine a coincidence defense

ID/Comparison of Man-Made Fibers
Fabrics that can be fitted together at their torn edge are easy to match Microscopic comparison of color and diameter Shape of fiber Combined factors: Color Twist patterns Size Shape Microscopic appearance Chemical composition, and dye content Make it very unlikely to find 2 different people wearing identical fabrics

Techniques UV-Vis or IR: Chromatography: Refraction:
Compares colors Chemical composition through spectral patterns Chromatography: Compares dye composition Refraction: ID’s fiber by refractive index Comparison microscope: Give shape, coloring, pitting and striations

Grant Funding

Grant Provide Funding for:
1. Development and implementation of a Lab Technician Program for Bioscience/Biotechnology Careers and education programs 2. Skill enhancement training for current employees of bioscience/biotechnology businesses and industries 3. Increased science opportunities for students in K-12 school systems served by the college

Objective 3 150 H. S. students will increase their literacy and numerical skills as a result of the enhanced science offerings over the project years H. S. students will complete 240 college credit science courses over the project years 20-40 science instructors will receive updated science information and enhanced lab skills annually 120 middle and H.S. students will participate in additional science activities annually

Thank you for your attention!!
This product was funded by a grant awarded under the President’s High Growth Job Training Initiative, as implemented by the U.S. Department of Labor’s Employment & Training Administration. The information contained in this product was created by a grantee organization and does not necessarily reflect the official position of the U.S. Department of Labor. All references to non-governmental companies or organizations, their services, products, or resources are offered for informational purposes and should not be construed as an endorsement by the Department of Labor. This product is copyrighted by the institution that created it and is intended for individual organizational, non-commercial use only.

Forensics Science for the Classroom Teacher

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