1. Crime Scene Investigation
Taylor, PVMHS
2015

2. Locard’s Principle of Exchange
When a person comes in contact with an object or another person, a cross-transfer of physical evidence occurs.
These transferred materials, constitute trace evidence.
Study of the material can determine the intensity, nature and duration of the transfer.
Example: more transfer occurs in a fist-fight than would in a simple brush of the arm.

3. Trace Evidence: transferred material
Pet hair
Fibers
Fingerprints
Human hair
Sand and soil
Paint chips
Broken glass
Feathers
Drop of blood
Building material

4. Types of Evidence Circumstantial Direct
Evidence used to imply a fact but not prove it directly.
Can be either physical or biological in nature.
Trace evidence is a type of circumstantial evidence.
Direct
Evidence that proves an alleged fact such as an eyewitness account, a video or dash cam, a confession.

5. Circumstantial evidence classified
Physical evidence
Synthetic fibers
Weapons
Bullets
Shell casings
Fingerprints
Footprints
Shoe prints
Tire impressions
Tool marks
Biological evidence
Body fluids
Blood
Semen
Saliva
Etc.
Hair
Skin cells
Fingernails
Plants
Pollen
Insects

6. Class vs Individual Evidence
Class evidence: Material that connects an individual or thing to a certain group.
Blood type
Hair
Soil
Tire marks
Anything that can be narrowed to a group but not a specific individual.
Individual evidence: Material that identifies a specific individual or thing.
Fingerprints
DNA
Anything that can be matched specifically to an individual.
Footprints
Shoe prints with specific wear patterns
Tire marks with specific wear patterns

7. Collecting and storing evidence
Liquids and arson remains: airtight, unbreakable containers
Biological evidence: breathable containers
Wet evidence should never be placed in a plastic container while wet, DNA will degenerate and evidence may grow mold.
Glass or ballistic evidence: carefully wrapped and placed in an envelope to prevent scratching or breakage.
Drugs or pharmaceuticals: sealed paper container, original pill bottle, or heat-sealed bags.
Documents: cellophane or plastic envelope.
Lifted latent prints: sealed envelope
Articles containing suspected latent prints: fastened to wood or cardboard for transport, handled as little as possible.
For more information visit

8. The Crime Scene Team who is at the scene of the crime?
Police officers: Generally the first to arrive at a crime scene.
Crime-scene investigators: Photographers, sketch artists, recorders to record data, & evidence collectors.
Medical examiner: Necessary if the crime scene includes a dead body.
Detectives: Interview witnesses & crime-scene investigators about the evidence.
Forensic “specialist's”: Entomologists, anthropologists, psychologists.

9. The 7 S’s of CSI… Secure the scene Separate the witnesses
Scan the scene
See the scene
Sketch the scene
Search for evidence
Secure the evidence

10. Secure the scene
Securing the scene is the responsibility of the first responder.
Check the safety of all individuals
Restrict unauthorized entry to preserve evidence
Keep a security log
Separate witnesses

11. Separate witnesses
Witnesses should not talk to each other (as you know!)
They could compare accounts
Key witnesses could create a “story”
Investigator questions to witnesses include:
When did the crime occur?
Who called in the crime?
Who is the victim?
Can the perpetrator be identified?
What did you see happen?
Where were you (positioned) when you observed the crime?

12. Scan the scene
The crime scene needs to be scanned to determine where photos should be taken.
Scan the scene to determine whether it is a primary crime scene (location where crime took place) or secondary crime scene (a location other than the initial crime scene that holds evidence that relates to the crime)

13. See the scene Photos need to be taken: in-situ distant
triangulation of stationary objects should be included as reference points
in-situ close up
with & without a ruler if possible
in collection paper with evidence label filled out and visible.

14. Sketch the scene
An accurate sketch of the crime scene (to scale) is necessary.
The position of any evidence/persons should be indicated.
All objects should be measured from two immovable objects.
North should be labeled.
A scale of distance should be included.
Landmarks or large/stationary objects should be included:
Furniture
Trees
Hedges
Fences
Cars
Doors
Windows
Street
Staircase

15. Search for evidence
Investigators may use a spiral, grid, linear, or quadrant pattern should be used depending on the number of investigators and the nature of the crime scene.
This allows for a systematic search, ensuring that no one area is left unsearched.
Alternate light sources may be required to locate some evidence (such as hair and fibers).
A special vacuum cleaner is sometimes used to collect evidence.
Flashlights, forceps, and magnifying glasses may also be used to collect small pieces of evidence.

16. Search patterns

17. Secure the evidence
Evidence needs to be properly packaged, sealed, and labeled.
Every piece of evidence needs an evidence label cataloging:
Case number
Item inventory number
Description of evidence
Name of suspect
Name of victim
Date and time of recovery
Signature of person recovering the evidence
Signature of witness present (if any) during evidence collection
Every piece of evidence must also have a chain of custody label on it.

19. What’s a bindle?
After evidence is allowed to air dry, it is packaged in a paper bindle.
The bindle then in placed inside a plastic or paper container.
The outer container is sealed and a chain of custody document and an evidence label are attached.
The size of the bindle depends on the size of the evidence.
Wrapping:
Choose appropriate size paper
Crease paper as shown below
Place evidence in X position
Fold left and right sides in
Fold in top and bottom
Insert top flap into bottom flap, then tape closed

20. Chain of custody Maintaining chain of custody is essential.
Every time a piece of evidence is opened and resealed, the chain of custody log needs to be signed.
This process ensures that all persons who have handled the evidence are accounted for and that the evidence is responsibly handled from crime scene to courtroom.
If just one “link” in the chain is broken the evidence may become inadmissible.

21. Biohazard
A biological agent that is a hazard to the health of humans or the environment.
Medical waste
Biological toxins
Microorganisms
Most frequently used in CSI to indicate the presence of blood and body fluids of unknown origin.
Sharps containers are for needles any other sharp medical instrument (IV, cath, scalpel, etc.)

22. Analyzing the evidence
Evidence will be sent to the forensic lab.
Danvers crime lab – Criminalistics
Maynard – DNA analysis
Lab technicians are specialized to process specific types of evidence
DNA
Arson & explosives
Firearms
Lab results are sent to the lead detective
Evidence is interpreted and compared to witness’ statements.

23. Reconstructing the scene
Based on the lab results from evidence analysis, detectives will form a hypothesis of the sequence of events that occurred from before the crime was committed through its completion.
Investigators must determine how all evidence fits:
Was evidence planted or staged?
What are all the possible scenarios that could have occurred?
How does the evidence (or how do the scenarios) compare to witness accounts?
Investigators must keep an open mind (no filters) as they piece the puzzle together.

24. Staged crime scenes
When evidence does not match the testimony of the witness.
Common crimes that are staged:
Arson
Suicide/murder
Burglary
As an investigator you:
Treat all deaths initially as a homicide.
Corroborate statements with evidence facts.
Reconstruct the event.
Conduct all forensic examinations to establish the facts.

25. Case study review
Review the case study from the book and the accompanying article.
Using your knowledge on investigating crime scenes, explain how evidence collected at the crime scene was critical to your case.

26. Case study review #1: Lillian Oetting
Three Chicago socialites were murdered in Starved Rock State Park, Illinois. All three women had fractured skulls. Their bodies, bound with twine, were found in a cave. Near the bodies of the women, a bloodied tree limb was found and considered to be the murder weapon. Because all three womenhad been staying at a nearby lodge, the staff of the lodge was questioned. Chester Weger, a 21-year-old dishwasher at the lodge, was asked about a blood stain on his coat. He said it was animal blood. He agreed to take a lie detector test and passed it. He was re-questioned and took a second lie detector test and passed it as well. The blood was examined by the state crime lab and found to be animal blood as Weger had indicated at questioning. The case reached a dead end. Investigators decided to revisit the evidence. The rope used to bind the women was examined more carefully. It was found to be 20-stranded twine sold only at Starved Rock State Park. Identical twine was found in an area accessible to Weger. He again became a prime suspect. The blood on his coat was reexamined by the FBI Crime Lab and found to be human and compatible with the blood of one of the victims. Weger submitted to another lie detector test and failed it. Weger was found guilty for the murder of one of the women, Lillian Oetting, and has spent more than 45 years in prison. He recently petitioned the Governor of Illinois for clemency, saying he was beaten and tortured into making the confession. He still maintains his innocence.

27. Case study review #2: The Atlanta child murders
Wayne Williams is thought to be one of the worst serial killers of adolescents in U.S. history. His victims were killed and thrown into the Chattahoochee River in Georgia. Williams was questioned, because he was seen near where a body had washed ashore. Two kinds of fiber were found on the victims. The first kind was an unusual yellow-green nylon fiber used in floor carpeting. Through the efforts of the FBI and DuPont Chemical Company, the carpet manufacturer was identified. The carpet had been sold in only 10 states, one of them being Alabama, where Williams lived. Thus, the fibers found on the victims were linked to carpet fibers found in Williams’ home. Another victim’s body yielded the second type of fiber. This fiber was determined to be from carpeting found in pre-1973 Chevrolets. It was determined that only 680 vehicles registered in Alabama had a matching carpet. Williams owned a 1970 Chevrolet station wagon with matching carpet. The probability of both types of fibers being owned by the same person was calculated. The odds against another person owning both carpet types were about 29 million to one. Williams was convicted and sentenced to two life terms.