1. Forensic science The application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system.

3. Physical Evidence Any material either in gross or trace quantities that can establish through scientific examination and analysis that a crime has been committed.

4. Classification of Physical Evidence Trace evidence Direct evidence Prima facie evidence Circumstantial evidence Exculpatory evidence  extremely small items  stands on its own to prove an alleged fact  evidence established by law  incriminates a person  helps to prove that an accused individual is not guilty

5. Another commonly used classification of physical evidence Corpus delicti Associative evidence  establishes that a crime has been committed  links suspect with the crime.

6. Physical evidence utilization in other areas of forensic investigation Provides investigative leads for a case Ties one crime to a similar crime or connects one suspect with another Corroborates statements from witnesses to or victims of a crime

7. The elements of a crime help to determine what will be useful as evidence. Besides knowing what types of evidence to search for, it is necessary to know where evidence is most likely to be found.

9. Characteristics of evidence Class characteristics Individual characteristics  features that place the item into a specific category  features that distinguish one item from another of the same type

13. Types of physical evidence BODY FLUIDS ÙConventional serology: òpresence of blood in stains òspecies identification and ABO grouping  is not adequately informative to positive identify a person ÙDNA analysis can associate victim and/or suspect with each other or with the crime scene BLOODSTAIN PATTERNS òadditional information SEM: erythrocytes & lymphocytes

14. Types of physical evidence BODY TISSUES  organ samples collected at autopsy, including blood, urine and stomach contents DRUGS & CONTROLLED SUBSTANCES  plant materials, powders, tablets, capsules òtoxicological analysis òvolatile compounds (ethanol, methanol, isopropanol) òheavy metals (arsenic) ònonvolatile organic compounds (drugs of abuse, pharmaceuticals)  miscellaneous (strychnine, cyanide) òtrace drug presence, identity, and quantity Black tar heroine wrapped in cellophane

15. Types of physical evidence DOCUMENTS Ùexamination òtyped, handwritten and printed materials for evidence of forgery  indented writings, obliterated or altered writings, used carbon paper, burned or charred paper Ùpaper and ink analysis Ùhandwriting comparison to determine authenticity Obliterated writing examination

16. Types of physical evidence HAIRS Ùhairs analysis can determine Ùmorphological features ÙDNA analysis  toxicological examination  FIBERS òhuman/animal òrace òbody area òcosmetic treatments òmethod of removal (crushed, cut, burned, forcibly removed, fallen out naturally) òcan associate a hair to a person òpositive identification  presence of drugs and poisons òtype òcolor, composition construction

17. Types of physical evidence Two matching hairs identified with the comparison microscope Flax fibers viewed with polarized light

18. Types of physical evidence FINGERPRINTS òthe strongest possible evidence of a person’s identity FIRE DEBRIS & EXPLOSIVES RESIDUE EXAMINATIONS òidentification of accelerants and explosive residues Fingerprint Matching Unburned accelerator liquid on a soot covered carpet

19. Types of physical evidence FIREARMS & AMMUNITION Ùindividual microscopic marks òidentification, source, operability of firearms. Ùdetection and characterization of gunpowder residues Ùmuzzle-to-garments distance estimation GLASS FRAGMENTS òCause of breakage òDirection of breakage force òPhysical fitting òGlass fragment comparisons Photomicrograph: test bullet - questioned bullet Glass fracture produced by a high-speed projectile

20. Types of physical evidence PAINT & PAINT PRODUCTS Ùanalysis and comparison of paint transferred from the surface of an object to another during the commission of a crime: òSuspect vehicle impacting a victim vehicle; a pedestrian or a stationary object òTool impacting stationary object ÙPaint databases can help identify the year, make and/or color of a motor vehicle from a chip of paint left at the scene. Paint Layers on Wood Surface

21. Types of physical evidence TOOLMARK IDENTIFICATION òmicroscopic side-by-side comparison òattempts to link a particular tool with a particular mark to the exclusion of any other tool ROPE & CORDAGE  composition, construction, color and diameter Spacing between teeth in gripping -major role in toolmark examinations òmanufacturer

22. Types of physical evidence SOILS & MINERALS òcomparison between two or more soils to determine if they share a common origin òcolor, texture, composition comparison WOOD òplace the suspect at the crime scene  side or end matching, fracture matching and species identification. Cross-section - Xylem Layers of soil exposed at a grave site. Each layer must be sampled

23. Types of physical evidence OILS/GREASE & COSMETIC PRODUCTS SHOEPRINTS & TIRE TREAD IMPRESSIONS òhave value for forensic comparisons. òcan provide positive identification of the suspect’s shoes or tires from the suspect’s vehicle. òpossess unique composition for comparison Shoeprint collected using a gelatin lifter.

24. Processing physical evidence discovering, recognizing and examining it; collecting, recording and identifying it; packaging, conveying and storing it; exhibiting it in court; disposing of it when the case is closed.