1. The Crime Scene Conducting a Systematic Search for Evidence
Various Types of Evidence
Collecting and Packaging Physical Evidence
Steps to a Crime Scene
Terms to Know 1

2. Forensics begins at the Crime Scene!
If the investigator cannot recognize physical evidence or cannot preserve it for the laboratory examination then the case could fall through. 2

3. CORPUS DELICTI “Body of the Crime”
You must prove:
that a crime has occurred
that the person charged with the crime was responsible for the crime
Top Reasons for Committing a Crime
Money
Revenge
Sex
Emotion--love, hate, anger
Source of Evidence
Body
Primary and/or Secondary Crime Scene
Suspect(s)

4. What is Physical Evidence?
Any object that can establish that a crime scene has been committed or can provide a link between a crime and its victim or between a crime and its perpetrator. 4

5. What is the value of Physical Evidence?
It can prove that a crime has been committed and set the scene for the investigation.
It can back up witness or prove it false.
It can link a suspect with a victim or with a crime scene.
It can determine the identity of people associated with a crime.
It can allow investigators to reconstruct a crime.
prove what has been committed – example, gasoline at the scene of a fire could prove arson
back up a witness – example, a scientist can test a bloodstain that suspect claims is his own and not the victim’s
link a suspect – example, a broken piece of headlight glass found in the cuff of a suspect’s pants could place him at the scene of a hit-and-run accident
identity – example, fingerprints, handwriting or DNA might prove that a certain person was present at a crime scene
reconstruct – example, blood spatter patterns may show where the suspect and victim were located relative to each other and indicate what happened and in what order

6. Evidence Characteristics
Class - common to a group of objects or persons; a group of objects that share properties or characteristics (this evidence considered mainly circumstantial)
Individual - can be identified with a particular person or single source.
ABO Blood Typing
Blood DNA Typing
Most evidence is class evidence.
A way to increase the probative value of class evidence is to find as many different types of objects as possible to link the suspect to the crime or the victim. Unfortunately, most of this evidence is circumstantial.
Wayne Bertram Williams was identified as the key suspect in the Atlanta Child Murders that occurred between 1979 and In January 1982, he was found guilty of the murder of two adult men. After his conviction, the Atlanta police declared an additional 23 of the 29 child murders solved. Williams was born and raised in Atlanta’s Dixie Hills neighborhood, from which many of the Atlanta Child Murderer’s victims would later disappear.
He first became a suspect in the child murder case in May His car was spotted directly above the sound of a loud splash heard in the river by a stake out team. He was stopped by police and questioned, and claimed that he going out of town to audition a young singer. His alibi fell apart after police found that the address and phone number he gave did not exist. Three days later, the nude body of 27 year old Nathaniel Cater, who had been missing for four days, turned up in the river. The medical examiner on the case ruled he had died of “probable” asphyxia, but never authoritatively said he had been strangled.
On June 21, 1981, he was arrested for the murders of Cater and 29 year old Jimmy Payne.
The evidence the police pooled together – theorized that Williams had killed Cater and had thrown him off the bridge the night they had pulled him over. He failed a polygraph test. Hairs and fibers on one of the victim’s bodies were found consistent with those from Williams’s home, car, and dog. People working with Williams told police they had seen him with scratches on his face and arms around the time of the murder. Eyewitness testimony placing Williams with different victims. Testimony that he was a pedophile attracted to young black boys. Only real evidence seems to be that blood stains from victims matched blood found in Williams’s car.
Williams never stopped proclaiming his innocence.
The jury found him guilty after only 10 hours of deliberation and he was sentenced to two consecutive terms of life imprisonment.
Latest updates on case – In February of 2007, officials agreed to allow the dog hair to be DNA tested against the hairs of Williams’s dog. Williams’s is still submitting appeals for his case.

7. Evidence
Transient Evidence – temporary, easily changed or lost, usually observed by the first officer at the scene
Odor - putrefaction, perfume, gasoline, urine, burning, explosives, cigarette or cigar smoke
Temperature - of room, car hood, coffee, water in a bathtub; cadaver
Imprints and indentations - footprints; teeth marks in perishable foods; tire marks on certain surfaces
Markings

8. Evidence
Pattern or Transfer Evidence -produced by direct contact between a person and an object or between two objects. There are several ways of classifying evidence. In this class, we will use:
Biological
Chemical
Physical
Miscellaneous

9. Biological Evidence Blood Semen Saliva Sweat/Tears Hair Bone Tissues
Urine
Feces
Animal Material
Insects
Bacterial/Fungal

10. Chemical Evidence Fibers Glass Soil Gunpowder Metal Mineral Narcotics
Drugs
Paper
Ink
Cosmetics
Paint
Plastic
Lubricants
Fertilizer

11. Physical (impression)
Fingerprints
Footprints
Shoe prints
Handwriting
Firearms
Printing
Number restoration
Tire marks
Tool marks
Typewriting

12. Miscellaneous Laundry marks Voice analysis Polygraph Photography
Stress evaluation
Psycholinguistic analysis
Vehicle identification

13. Evidence
Conditional Evidence - produced by a specific event or action; important in crime scene reconstruction and in determining the set of circumstances within a particular event.
Light--headlight; lighting conditions
Smoke--color, direction of travel, density, odor
Fire--color and direction of the flames, speed of spread, temperature and condition of fire

14. Evidence Conditional Evidence (cont.)
Location--of injuries or wounds; of bloodstains; of the victims vehicle; of weapons or cartridge cases; of broken glass, etc.
Vehicles--doors locked or unlocked, windows opened or closed; radio off or on (station); odometer mileage
Body--position; types of wounds; rigor, livor and algor mortis
Scene--condition of furniture, doors and windows; any disturbance or signs of a struggle.
After talking about Physical evidence, read “Fracture Math” and “Richard Crafts” on pgs

15. Steps to a Crime Scene: Secure and isolate the crime scene.
Done by the 1st officer on the scene.
Lead investigator evaluates the site.
Set the boundaries of where the crime occurred.
Locate where the perpetrator entered and exited the scene.
Conduct a systematic examination of the scene.
Record the scene. (photos/sketches/notes) 15

16. Crime Scene Team
A group of professionals investigators, each trained in a variety of special disciplines.
Team Members
First Police Officer on the scene
Medics (if necessary)
Investigator(s)
Medical Examiner (if necessary)
Photographer and/or Field Evidence Technician
Lab Experts
pathologist serologist
DNA expert toxicologist
forensic odontologist forensic anthropologist
forensic psychologist forensic entomologist
firearm examiner bomb and arson expert
document and handwriting experts fingerprint expert

17. Photographing a Crime Scene
Photos are taken at different angles to get a clear view of the scene.
If items/people are removed that should be noted on the photo.
Photographs are taken of all the physical evidence that is collected.
Digital cameras are the best since you can piece together several pictures for a 3D view.
Video cameras are good for the added bonus of sound records. 17

18. Sketching a Crime Scene
Rough Sketch
Draft representation of all the essential information and measurements at a crime scene. Drawn at the scene.
Finished Sketch
Precise drawing of a crime scene drawn to scale. (Drawn with care)
Use of computer CAD programs is most common. 18

19. Rough Sketch 19

20. Finished Sketches 20

21. 21

22. Conducting a Systematic Search for Evidence
Spiral Search
Grid Search
Start
Finish
Quadrant / Zone Search
Strip / Line Search 22

23. Conducting a Systematic Search for Evidence
After the search is conducted at the scene more evidence can be collected off of the suspects.
If there is a dead body evidence is looked for on their clothing, fingernail shavings, head/pubic hairs, vaginal/anal/oral swabs, and hand swabs for GSR. 23

24. Collecting and Packaging Evidence
Must be done correctly and accurately to maintain the integrity so that the evidence can prove the case.
Each piece of evidence must be separately collected and packaged 24

25. Collecting and Packaging Evidence
Chain of Custody
List of all the people who came in possession of an item of evidence.
This is very important when establishing validity in a court case. 25

26. Collecting and Packaging Evidence
Standard / Reference Sample
Physical Evidence whose origin is known and can be compared to an unknown.
Examples:
Soil from a known source vs soil from crime scene.
DNA from a suspect vs DNA from crime scene.
Substrate Control
Used mainly in arson cases. A piece of unmarked material is used to compare to the marked material.
Example:
A burnt piece of countertop is compared to an non-burnt piece of the table top. 26

27. Terms to Know: Buccal swab Chain of Custody Finished Sketch
Rough Sketch
Physical Evidence
Standard/Reference Sample
Substrate Control 27