1. Importance of Evidence
Chapter 2
Importance of Evidence

2. Physical Evidence
Any material present at the crime scene, on the victims, or the suspect.
Can be at primary or secondary crime scene.

3. Physical Evidence
What will physical evidence found at the crime scene do for the investigation?
May prove that a crime has been committed
Establish key elements for a crime
Link a suspect with a crime scene or a victim
Establish the identity of a victim or suspect
Corroborate verbal witness testimony
Exonerate the innocent
Give detectives leads to work with in a case

4. Trace Evidence
Refers to physical evidence that is found in small but measureable amounts.
Examples include:
Strands of hair
Fibers
Skin cells

5. Testimonial Evidence
Oral or written statements given to police as well as court testimony by people who witnessed an event.
Can include court testimony by people who witnessed an event.
Testimony from _________ witnesses is very important in court.

6. Class vs. Individual Characteristics
Determining whether evidence is from a group or a specific source is crucial in investigations.
These associations may help investigators determine a link between the crime scene, parties involved, and/or the evidence.

7. Class Characteristics
Recurring characteristics shared by one or more objects in a group.
All objects in this group will have the exact same characteristics.

8. Ch. 2 Sec. 1 Notebook Quiz 1) What is physical evidence?
2) What can physical evidence found at a crime scene do for the investigation?
3) Define and give 3 examples of trace evidence.
4) What is testimonial evidence?
5) Determining whether _____ is from a _______ or specific source is _____ in _____.
6) What is the difference between class and individual characteristics?

9. Example
All size 10 Nike Air Force size 10 shoes are manufactured to have a particular design.
All will have the same general appearance.
This is what distinguishes it from other shoes.
If we find this print at a crime scene, it will tell us the type of shoe but not the person who owns it.

10. Individual Characteristics
Random, unique features of an object that set it apart from other objects with the same class characteristics.
All objects in the same group will not have the same individual characteristics.

11. Example
Continuing with the footwear theme: cuts scratches, abrasions, foreign objects (rocks), not general wear, etc.
These characteristics are unique to 1 and only 1 particular shoe.
Individual characteristics are
very important pieces of
evidence.

12. Class vs. Individual Characteristics Activity
Tire track 8) Duct tape
Blue hat 9) Baseball bat
Social security card 10) License plate
Human skin cells 11) Fingerprint
# 2 Pencil with bite marks 12) Extension cord
Empty Advil bottle ) Nike Air shoeprint
.22 Rifle bullets (unfired) 14) Blood droplet

13. Forensic Vocabulary
Motive: the cause that induces people to complete a certain action
Intent: the design or purpose to commit an act
Catalyst: substance that accelerates a chemical reaction
Conclusive evidence: evidence that may not be disputed and must be accepted by the court as a definitive fact

14. Forensic Vocabulary
Fingerprint: unique patterns created by skin ridges found on the palm sides of fingers and thumbs
Gene: unit of inheritance consisting of a sequence of DNA
Indicator: chemical used to determine the presence of an acid or a base
Microscopic hair analysis: procedure of examining hair shafts for identifiable characteristics

15. Forensic Vocabulary
Chromatography: process of separating a chemical mixture into individual substances
Composite drawing: sketch of a suspect produced from one or more eyewitnesses
Criminology: study of criminal activity and how it is dealt with by the law
DNA profiling: process of testing to identify DNA patterns or types

16. Intro. To Forensic Anthropology
Anthropology: study of humans, past and present
In forensics, it is studying the remains of humans in order to help solve a crime.
How can studying remains of humans be helpful in a forensic investigation?
What things can be learned from studying skeletal remains?

17. Case Study # 9
A robbery has occurred at 1216 E. Main St. The front glass window was discovered broken and all inventory has been stolen. Small blood droplets were discovered on the sidewalk outside of the store. No blood was discovered inside the store. There were no cameras inside the store. No fingerprints or other pieces of evidence were found. Based on this information, answer the following questions:

18. Case Study # 9: Review Questions
1) What evidence was present?
2) Can you solve the crime based on this evidence? Why or why not?
3) List 2 things that this evidence can tell you about the suspect. Why is this important?
4) Which is more useful in blood evidence: DNA Sequence or Blood Type? Why?
5) Is there anything suspicious about finding the blood evidence on the outside instead of the inside of the store?

19. Case Study # 11
Police receive a letter from an 8 year old girl that goes by Lauren. Lauren has been missing for 3 weeks. It had been presumed that she was kidnapped because on the day she went missing, her dad was released from prison. In the letter, the girl states that she is fine and requests that police call off the search for her. It also states that she has found a new home where she will be taken care of. The entire letter is written in cursive, contains no grammatical errors, and is signed Ellie (her first name that no one calls her).

20. Case Study # 11: Review Questions
1) Why was it presumed that Lauren was kidnapped?
2) Who is the prime suspect in the crime?
3) What is suspicious about the way the letter is written?
4) What is suspicious about the way the letter is signed?
5) How could investigators verify that this is indeed Lauren’s handwriting?

21. Case Study # 12
A robbery has occurred at the First National Bank in Bloomington, Indiana. 2 masked men entered the bank at 9:00 A.M. carrying pistols and empty bags. They forced all customers and employees onto the ground upon entering. After collecting the money, one of the men dropped his wallet containing his social security card. Suspect # 2 took off his mask when exiting the bank and his face was captured on camera.

22. Case Study # 12: Review Questions
1) Where did the crime take place?
2) What type of crime has occurred?
3) List the pieces of evidence that were found as well as if each has class or individual characteristics.
4) How can the evidence be used to locate the suspects?
5) Were there any witnesses? If so, how would they be useful in solving this case?