CSICrimeScene

Investigator

Job of a Crime Scene Investigator

1. Evaluate the Crime Scene

2. Reconstruct the crime

3. Find the evidence left at the crime scene

4. Collect the evidence

5. Use forensics to solve the crime

Evaluate the Crime Scene

Walk through the crime scene

• Secure the scene

• Document the crime scene

• Reconstruct the crime scene

• Involve the district attorney

Secure the Crime Scene

• Block off the area with yellow crime tape

• Why?

• Untainted search

• Do not want any evidence destroyed or tampered with

• Police must guard the area

Document the crime scene

1. Sketch the crime scene

• Measure the area

• Draw the location of the body

• Draw in all details

Document the crime scene

2. Take notes

• Describe what you see

• Describe what you hear

• Describe any smells

• All observations

Document the crime scene

3. Take pictures and videos before touching any evidence

• Crime scene photographers must take pictures of everything

Involve the District Attorney

• DA

• Help CSI get search warrants

• They must get warrants from a judge

• This makes all evidence collected legal and admissible in court

Reconstruct the Crime

• Using your own observations

• Try to reconstruct what you think happened

• Create a scenario of the crime

Reconstruction of Crime

• Who did it?• What happened?• When did it happen?• Did it happen here or was another crime scene

involved?• Who is the victim?• Why was the crime committed? Motive• What evidence is there to help prove the

motive?

Find Evidence

• Goal: Find, Collect, and Preserve all Physical Evidence

Physical Evidence

1. Trace Evidence (gunshot residue, paint residue, broken glass, unknown chemicals, and drugs)

2. Impressions (teeth, shoes, tool marks)3. Body fluids (blood, saliva, semen, vomit)4. Hair and Fibers5. Weapons and Firearms6. Questioned Documents (suicide notes,

receipts, diaries, or phone books)

                                                         

Searching for Evidence

Parallel Search

1. All members of the CSI team form a line

2. They walk a straight line, at the same speed

3. They cover the entire crime scene

4. Pick up any evidence

What are you looking for?

• Doors and windows: open, shut, locked?• Room: clean, messy, chaos• Mail: It is opened or closed• Kitchen: Is there food partially eaten? Is

the table set? For how many?• Was there signs of a party? Empty

glasses, alcohol, cigarettes; lipstick or teeth marks

• Is anything out of place or weird?

• Is there trash in the trash cans? Is there anything out of the ordinary in the trash? If not, someone might have been looking for something in the victim's trash.

• Do the clocks show the right time? • Are the bathroom towels wet? Are the

bathroom towels missing? Are there any signs of a cleanup?

• If the crime is a shooting, how many shots were fired? The CSI will try to locate the gun, each bullet, each shell casing and each bullet hole.

• If the crime is a stabbing, is a knife obviously missing from victim's kitchen? If so, the crime may not have been premeditated.

• Are there any shoe prints on tile, wood or linoleum floors or in the area immediately outside the building?

• Is there any blood splatter on floors, walls or ceilings?

Preserving and Tagging Evidence

• Goal: Preserve evidence for forensic analysis and collect it in a way that will make it admissible in court

Evidence Collection

1. Wear latex gloves

2. Place all evidence in brown envelopes or plastic baggies

3. Label all bags or envelopes with type of evidence

4. Evidence collect from suspect interviews must be labeled with the suspects name and type of evidence

Interviewing Suspects

Forensic Tests

• Evidence must be sent to the forensic lab for analysis

• A specialist will perform the test and send back the results

• CSI works as team