Chapter 2

The Crime Scene

Crime Scene

The location & surrounding

areas where a crime has been

committed

Physical Evidence Any & all objects that:

establish a crime link a crime to its victim link a crime to its perpetrator

Must be recognized at scene & preserved!!

Processing the Crime Scene

1. Preserve Life

2. Protect Area

3. Photograph

4. Sketch

5. Notes

6. Search

7. Collect

8. Package

9. Chain of Custody

Step 1: Preserve Life

Get medical help for those who need it

Arrest suspect

Step 2: Protect Area

Keep out all unauthorized people

Rope off, barricade, station guards

Step 3: Photograph The unaltered scene so don’t

move a thing!!

Crime scene & adjacent areas

From all angles & overviews

Photographs continued…

Body position & location

Close-ups of evidence, injures, weapons

Place ruler by object for reference

Step 4: SketchesA. Rough Sketch

shows evidence & important features

use tape measure distances must be

measured from 2 fixed points (walls)

Sketches continued…B. Finished Sketch

very accurate & drawn to scale

drafting tools & computer programs used

Step 5: Notes Detailed written description of crime

scene & evidence

Provide time & person who found evidence

Record who & how it was packaged where it was sent

Step 6: Search

Systematic & thorough

Establish points of entry & exit

Victim’s body is also searched at autopsy

Step 7: Collect Avoid contamination!!!

Keep in original condition

Bloodstains scrape off surface

transfer to moist swab

cut out stain

Step 8: Package Evidence must be packaged

separately

Label/Tag officer’s initials

location it was found

time

Packaging Continued … The following items are useful:

forceps manila envelops unbreakable containers/pill

bottles with lids screw-cap glass vials

Packaging Fire/Arson Evidence

Use airtight containers b/c they trap fumes

Packaging Wet Bloodstained Materials

Do not use airtight containers

Place in paper bags to dry

Transfer to crime lab in BIOHAZARD bags

Step 9: Chain of Custody

Transfer of evidence

A list of every person the evidence was passed on to

Keep chain as short as possible

What should be collected?

1. Victim’s clothing

2. Fingernail scrapings

3. Hair

4. Blood (DNA)

5. Vaginal, anal, & oral swabs (sex crimes)

6. Recovered bullets from body

7. Hand swabs (gunshot residues)

Standard/Reference Samples

Sample of known origin (control)

Compare it to crime scene evidence

Ex: Paint from suspect’s car & paint found on victim

Crime Scene Safety1. Latex gloves (doubled) & shoe

covers2. Masks / goggles / face shield /

coveralls3. Biohazard bags & labels4. Contaminated equipment

disinfected with 10% bleach solution5. No smoking, drinking, or eating

Court Cases

Mincey vs. Arizona Drug dealer undercover cop killed

4-day search at homicide scene

No warrant

Guilty verdict reversed

Michigan vs. Tyler Business fire search conducted

morning after

3 other searches (4,7, & 25 days later)

No warrant

Guilty verdict reversed

4th AmendmentProtects against unreasonable

searches & seizures

Warrants must be obtained when time & circumstance permit it

A Warrant is NOT Needed When:

It’s an emergency

You’re being arrested

You give your permission

Evidence is in danger of destruction