1. Analyzing the Crime Scene
Chapter 2
Forensic Science
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2. Approaching a Crime Scene
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3. Vocabulary to Know First responder Chain of Custody
Individual evidence
Paper bindle
Primary crime scene
Secondary crime scene
Trace evidence
Direct evidence
Inductive reasoning
Deductive reasoning
Chain of Custody
Circumstantial evidence
Class evidence
Crime scene investigation
Crime scene reconstruction
modus operandi

4. Locard’s Exchange Principle
Established by
Dr. Edmond Locard
Director of 1st forensic lab in Lyon, France.
States: when a person comes in contact with an object or another person, a cross-transfer of physical evidence occurs. The evidence is known as trace evidence.
"It is impossible for a criminal to act, especially considering the intensity of a crime, without leaving traces of this presence."

5. Types of Trace Evidence
Hair
Fibers
Skin cells
Pollen
Glass fragments
Paint chips
Makeup, etc.

6. Classifying Evidence Direct Evidence: Circumstancial evidence:
1st hand observations; eyewitness video.
Circumstancial evidence:
Indirect evidence implies fact but doesn’t prove.
2 types – physical and biological

7. Classifying Evidence - Circumstancial
Also called Indirect Evidence
Physical
Impressions
Fingerpints, shoeprints, tire prints,tool marks.
Synthetic fibers
Shell casings
Bullets
Weopons
Biological (more pursuasive)
Body fluids
Hair
Plant parts
Natural fibers
Blood

8. Classifying Evidence Class Evidence
Place evidence into groups. Make or model or objects
Individual Evidence
Place evidence to an individual person or thing.

9. Approaching a Crime Scene
Personal Safety and the well being of victims is paramount.
Secure / Preserve and Isolate the crime scene. Video
Record the crime scene in photos, sketches and notes.
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10. CSI Team Police officers CSI ME (medical examiner) Detectives
Recorders, sketch artists, photographers, evidence collectors.
ME (medical examiner)
Detectives
Specialists
Entomologist, psychologists, anthropologists

11. 7 S’s of CSI Secure crime scene Separate witnesses Scan scene
Seeing the scene
Sketch the scene
Searching for evidence
Securing and collecting evidence

12. 7 S’s: Secure the Crime Scene
Done by 1st responder
Restrict all unauthorized persons from entering cs.
Keep security log of all who visit cs.
Keep evidence from getting contaminated.

13. 7 S’s: Separating Witnesses
Keep witnesses from comparing or creating a story (collusion).
Ask each witness the following ?’s.
when did the crime occur?
Who called in the crime?
Who is the victim?
Can the perp. be identified?
What did you see happen?
Where were you when you observed the crime?

14. 7 S’s: Scanning the Scene
Scan scene to determine where photos need to be taken.
May occur at both primary & secondary cs.

15. 7 S’s: Seeing the Scene CS examiner must see (observe) the scene.
Photos must be taken w/ & w/o measuring ruler.
Triangulation of stationary obj. should be included as reference pts.
View cs from several different angles.

16. Recording the Crime Scene
Photographs /videos
Software.
Sketches
Notes
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17. Photography Evidence Scene Close ups Perspectives Multiple angles
Multiple views
Entrances
Exits
Windows
Different Wavelengths of photography: IR or UV
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18. 7 S’s: Sketching the Scene
Rough Sketch
Should include:
Position of any evidence or victim.
All objects measured from two stationary landmarks
North labled
Scale of distance provided
Any objects in vicinity of cs. (doors, windows, furniture)
If outdoors, position of trees, vehicles, hedges, and other structures should be included.
Final Sketch
Very accurate; could be used in court.
In addition to RS include:
Case #
Date
Location
Name

19. Rough Sketch of the Crime Scene
The initial documentation of the crime scene.
Often a hand drawn representation of the scene by investigators.

20. Rough Sketch to Final
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A computer drawn CAD version of the combination of the rough sketch and notes from the investigators.

21. Sketch Examples

22. 7 S’s: Searching for Evidence
Search patterns:
Grid
Linear
Quadrant or Zone
Spiral
Single investigater may use grid, linear or spiral.
Group – linear, zone or quadrant.
Flashlight & forceps are equipment of choice. Keeps from picking up extraneous materials.

23. Notes Match to sketch Use a numbered key Quick, short, bulleted
What can you not see from the photo?
Critical Observations of the scene. Use all senses.
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24. Types of Search Patterns

25. 7 S’s: Securing & Collecting
Must be properly packaged, sealed & labeled
Packaging Examples:
Liquids & arson: stored in airtight, unbreakable containers
Most biologicals: breathable containers so evidence can dry out – reduces chance of mold contamination. Package in paper bindles.
Once proper containers are used, place in plastic or paper container. Then:
Seal with tape.
Label across tape by collector
Evidence log & chain of custody attached to evidence container.

26. 7 S’s: Securing & Collecting
2. Evidence Log includes:
Case #
Item inventory #
Description of evidence
Name of suspect
Name of victim
Date & time of recovery
Signature person recovering evidence
Signature of any witness present during collection.

27. Collecting Evidence Victim's clothing Fingernail scrapings
Head and pubic hairs
Blood (for typing and DNA purposes)
Video FBI training film
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28. Vaginal, anal, and oral swabs
Recovered bullets from the body and/or surrounding area
Hand swabs or washings from shooting victims
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29. 7 S’s: Securing & Collecting
3. Packaging Evidence
Choose appropriate size sheet of clean paper for bindle.
Crease paper in grid pattern
Place evidence in center grid
Fold in left then right sides
Fold over top & bottom
Insert top flap into bottom flap & tape closed.
Place bindle inside plastic/paper bag. Fold bag closed.
Place seal over folded edge of evidence bag.
Collector writes name over folded edge.
Remember: large, wet object should be placed in paper container & sealed to allow for air drying.
Control samples must also be taken from victim for the purpose of exclusion.

30. Chain of Custody
Chain of custody (CoC), in legal contexts, refers to the chronological documentation or paper trail, showing the seizure, custody, control, transfer, analysis, and disposition of physical or electronic evidence.
Particularly important in criminal cases, the concept is also applied in civil litigation – and sometimes more broadly in drug testing of athletes, traceability of food products and to provide assurances that wood products originate from sustainably managed forests.

31. Chain of Custody *Very Important*
Tech opens packaging at some other location except where originally sealed.
After examination, evidence is repackaged in original container where it was removed & placed in a new package.
Seal new packaging with techs signature on seal.
Tech also signs chain of custody log attached to package.
Individual that finds the evidence marks it for identification & bags evidence in plastic/paper container.
Placed in final container & labeled with pertinent info.
Container is sealed & collectors signature across sealed edge
Pass onto person that will transport to lab who signs it over to technichian.

32. Analyzing Evidence Crime Scene Reconstruction
Crime scene reconstruction completed using evidence (before crime to its completion)
Evidence used to co-oberate witness accounts
Direct evidence more compelling than circumstancial.
Staged Scenes
Poses unique problems. Evidence doesn’t match witness testimony.
Common staging situations.
processed by tech that specializes in specific areas of forensic science
Evidence results sent to lead detective

33. Inductive and Deductive Reasoning
Induction and deduction reasoning methods. Arguments based on experience or observation are best expressed inductively, while arguments based on laws or rules are best expressed deductively. Inductive reasoning moves from specific details and observations to the more general underlying principles of who did it.
deductive reasoning typically moves from general truths to specific conclusions

34. Police Sketches of Criminals
Police sketch artists will convert a victim or eyewitness description to a depiction of the suspect.
Video

35. Level Types of Evidence: Class or Individual
Class level evidence is a characteristic of evidence that points to a group of objects or people. Example: new tennis shoes… that lots of people could have.
Individual level evidence is a characteristic of evidence that pinpoints a singular person or object. Example: DNA
Video

36. Crime Scene Evidence
There are many different types of evidence found at a crime scene. Any of these could be a significant piece in solving the crime. The significance of each piece of evidence is often unknown until after the evidence has been bagged, labeled, and sent to the lab.
For these reasons, forensic scientists treat each and every piece of evidence as if it is vital. Every object at a crime scene is considered to be significant until toughly examined.

37. Types of Analysis
Comparison: Most types of evidence require a control with which to be compared (example: fingerprints, hairs)
Visual : Evidence that can be utilized or compared through unaided observation, (example: fingerprints, tool marks)
Microscopic (trace) analysis that evidence that must be observed with the use of some type of microscope (example: hairs, fibers)
Chemical : If an article of evidence must be subjected to chemical analysis (example: DNA typing, drug screening). Can be Trace Evidence

38. Common Types of Physical Evidence
Documents. Any document, handwritten or printed, will be submitted so that authenticity and source can be determined. These types of analysis are utilized mainly with ransom notes, suicide notes, death threats, and forgeries.
Glass. Glass panes, particles, or fragments that are found or transferred to a person or object involved in a crime may be substantial evidence. Such evidence, whether broken by a bullet or fingerprints, may link a suspect or piece of evidence to a crime scene, and be used to deduce cause of breakage or direction of penetration.
Fingerprints a mainstay in criminal investigating. When a person touches an article with their bare hands that a print is left behind. Such prints are called latent prints. with the utilization of computers and large databases, identifying a suspect’s prints have become routine.

39. Common Types of Physical Evidence
Hairs are often found at a crime scene and are fairly easy to compare and identify with the use of a microscope. Any animal or human hair present at the scene could link a person or animal with a crime. With a number of samples to compare, hairs from a crime scene may be matched to a suspect with a high degree of certainty. Upon the discovery of a root or follicle tissue, DNA analysis can provide an exact match.
Body or parts are often found in scenes that involve the most serious of crime. DNA, Anthropology, Odontology can reveal the identity.

40. Common Types of Physical Evidence
Soils, Minerals, Wood, and Other Vegetative Matter. Any items containing soil, minerals, wood, or other vegetative matter could link a person or object to a particular location (for example, soil imbedded in shoes and vault insulation found on garments).
Fibers are any natural or synthetic fiber transferred which may be useful in establishing a relationship between objects and/or persons. They may be able to predict if such a fiber originated from clothes, towels, carpet, or other sources.

41. Common Types of Physical Evidence
Firearms as well as ammunition, are often important evidence in an investigation. In fact, it is often impossible to get a conviction in shooting cases without the discovery of such evidence.
Powder Residue. A person or item may be suspected of containing firearm discharge residue. The presence and disbursement of powder residue is used to discern if, when, and where a firearm may have been fired.

42. Common Types of Physical Evidence
Explosives and petroleum products. These products are devices containing an explosive charge, as well as all objects removed from the scene of an explosion or fire that are suspected to contain the residues of an explosive material. The placement and appearance of these items is significant in determining where a fire or explosion originated and advanced. After collection and analysis, the chemical composition of such may be helpful identifying the origin and users of the substances.
Video

43. Common Types of Physical Evidence
Impressions and Tool Marks. Impressions include tire markings, shoe prints, depressions in soft soils, and all other forms of tracks, glove and fabric impressions, and bite marks in skin or foodstuffs.
Drugs. Any substance in violation of laws regulating the sale, manufacture, distribution, and use of drugs or chemicals will be seized.
In addition to the large number of illegal drugs which are manufactured, sold, and used, a large number of perpetrators committing other crimes

44. Common Types of Physical Evidence
Paint. Any paint, wet or dry, may be transferred from the surface of one object to another during the perpetration of a crime. Most paint evidence originates from crimes involving hit-and-runs. With a control sample to compare a suspected sample, paint can be matched to a vehicle with near 100% certainty.
Blood, Semen, Saliva, Organs, and other Physiological Fluids. All body fluids, animal or human, will be subjected to biochemical analysis for determination of identity and origin. By examining the amount, color, and distribution of such fluids, an investigator may able to make several predictions about what took place at a scene.

45. Collecting Evidence
Bag & Tag evidence according to standard operating procedures
College class example video
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46. Collecting Controls
Controls are samples that help eliminate the innocent bystanders and those not considered as suspects. They include fingerprints, DNA Samples, Hair, and other evidence from possible suspects or victims for comparison to evidence.
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47. Search Warrants
A search warrant is a court order issued by a magistrate, judge or Supreme Court official that authorizes law enforcement officers to conduct a search of a person, location, or vehicle for evidence of a crime and to confiscate evidence if it is found. A search warrant cannot be issued in aid of civil process.

48. When is a Warrant Required for Evidence Collection?
The Fourth Amendment to the United States Constitution protects Americans from unreasonable searches by the government.  That means that absent an emergency situation or other legal exception, a police officer must have a search warrant before conducting a search of your person or property.

49. How to Get a Warrant?
A judge will only approve a search warrant if law enforcement is specific as to the items and location it wishes to search.  Law enforcement must also prove that probable cause exists that a specific item is located in a specific place.
Whether the warrant gets issued or not is up to the judge's review.  If a judge finds that law enforcement has met its burden of probable cause and has included enough specificity in the request for the warrant, then the judge will issue the search warrant.

50. When is Search Warrant NOT Necessary?
Consent: Law enforcement can request to enter a person’s home or search a person’s belongings
Plain View Doctrine:  Law enforcement does not need a search warrant to obtain evidence that is in plain sight. 
Emergency Situation: If the police are in hot pursuit of a felon and follow that alleged felon into a home or other private area then they do not need a warrant to obtain evidence that is in plain sight when they enter the building.
Search Incident to Arrest: Police officers may search the body and immediate surroundings of a person whom they take into custody. 

51. Review of the Crime Scene Analysis
Video