Searching a Crime Scene

1
Chapter 2.2

• Searching a Crime Scene

2
Objectives

• Describe proper procedures for conducting a
  systematic search of crime science for physical
  evidence
• Describe proper techniques for packaging common
  types of physical evidence
• Define and understand the concept of chain of
  custody

3
Conducting a Systematic Search for Evidence

• Investigator responsible for assigning people to
  search the crime scene
• Process depends on locale, size of area, and
  actions of the suspect(s) and victim(s) at the
  scene
• One person is in control
• Latent fingerprints required
• Relevant physical evidence is determined by the
  crime

4
Systematic Search

• Image on page 41

5
Systematic Search Cont

• Vehicle search must be detailed according to the
  nature of the crime in which a vehicle is
  suspected
• Some evidence is only trace and therefore objects
  at the scene may contain trace and therefore are
  collected

6
Systematic Search Cont

• Clothing is taken from all participants in a
  crime
• Areas of the crime should be vacuumed and swept
  for trace
• portable vacuum with special filter is used

7
Systematic Search Cont

• Fingernail scrapings obtained
• Autopsy
• victim clothing
• fingernail scrapings
• head and pubic hair
• Blood

• vaginal, anal, oral swabs
• if sex related
• recovered bullets from the body
• hand swabs from shooting victims

8
Collect and Package Physical Evidence

• Must be handled and processed so that no change
  occurs between scene and lab
• Changes include contamination, breaking,
  evaporation, scratching or bending, lost
• Each item is packaged separately

9
Collect and Package Physical Evidence

• Bloodstained evidence is best in paper rather
  than airtight containers
• Charred material must be stored in airtight
  container to prevent evaporation

10
Maintain Chain of Custody

• List of all person who were in possession of the
  item
• Collector includes initials, location of evidence
  and date

11
Obtain Standard/ Reference Samples

• Physical evidence whose origin is known to be
  compared to that evidence at the crime scene
• Hair
• paint from car
• buccal swab (cheek)
• substrate controls
• uncontaminated surface material close to where
  the physical evidence is found

12
Submit Evidence to the Lab

• Evidence submission form
• Request for examination of evidence must be
  detailed
• Can be personal delivery or mail shipment

13
In-Class Assignment/Homework

• 2.2 Review Questions