Processing the Crime
Scene
What is physical Evidence?


Any and all objects that can establish that a
crime has been committed
OR
Can provide a link between a crime , its
victim or a crime and the perpetrator
What’s the first thing to do at a crime
scene?
1. Secure and isolate
crime scene
2. Record the scene
3. Conduct Systematic
Search for Evidence
4. Collect and Package
Physical Evidence
5. Maintain Chain of
Custody
Secure and Isolate Crime Scene

Responsibility of first officer on scene (take steps
to preserve and protect scene)



First priority - medical assistance
Exclude all unauthorized personnel
Establish and Control entry / exit points
Ropes, Tape, Barricades and Guards
placed.
strategically
Once the scene is secure and lead
investigator arrives – what happens?

Boundaries of Scene determined




Does the area being searched need to be expanded?
Establish perpetrator’s path of entry and
exit
Obvious items photographed and
documented
Initial walk through to gain overview and
develop strategy for systematic search
Record the Scene

Name Three ways you could permanently record the scene:
1. Photograph
2. Sketch
3. Notes
Photography

Crime scene should be photographed in its
entirety.




Where the crime happened and adjacent areas.
Pictures of evidence to show location and
position relative to entire scene.
Close-ups to show injuries and physical evidence
Measuring scale should always be included
Videotaping is also useful




Long shots and close-ups
Narration of events and scenes being videotaped
can be useful for later analysis.
Sights and sounds of crime scene can be
recorded.
Provides comparison to determine if scene has
been altered or evidence moved during
investigation.
Still photography continues to be the
preference for the majority of crime labs.
Sketches



Once photographs have been taken,
sketches are created.
Investigator may not have time or skill so a
ROUGH sketch is always created at scene.
Finished sketch is finished after all data has
been collected.
Notes

Constant Activity throughout the process of
investigating a scene.
Notes must include:
- detailed written description of the scene
- Location of physical Evidence
- Records time that each piece of evidence was discovered.
- Record who discovered the evidence and how they packaged it
Notes should be taken with great detail and in anticipation that this may be the
only source of information for refreshing one’s memory after weeks, months or
years of an investigation.
Search


Search for physical evidence must be
systematic and thorough.
Type of search depends on size and
location
Collect and Package Physical
Evidence

Physical evidence must be handled and
processed in a way that prevents any
change from the time it is removed to the
time it arrives at the lab.
What are some sources of contamination?
Breakage
Evaporation
Accidental Scratching or bending
Loss through improper Careless
packaging
Chain of custody




Continuity of possession
Established when evidence is presented in
court
Info. Collected: initials, date,location of
evidence
To avoid confusion and retain control at all
times – individuals on chain of custody
should be kept to a minimum.
Removal of All evidence must be in
accordance with appropriate search and
seizure protocols.
2 Classifications of Evidence – used
for comparison analysis


Individual Characteristics
Class Characteristics
Individual Characteristics


Evidence that can be associated with a
common source with an extremely high
degree of probability.
Examples:

Fingerprints, striation marks on bullets, tool
marks, footwear impressions, the comparison of
handwriting characteristics, the fitting together of
the irregular edges of broken objects (puzzle)
Class Characteristics



Evidence that can only be associated with
a group and never a single source.
Most items of physical evidence retrieved
at a crime scene cannot be linked
definitively to a single person.
Examples: Blood type, Layer of paint from
a car, carpet fibers, etc…
Legal Considerations at a crime scene:
Which Ammendment protects us from
The 14th Ammendment
Unreasonable searches?
A number of allowances have been made by the courts to
justify a warrantless search….what do you think they are?
1. Emergency Situations
2. Need to prevent immediate loss or destruction of evidence
3. Search made by consent of the parties involved.
Mincey V. Arizona

Court dealt with a four day search at a
homicide scene.
Involved raid on Rufus Mincey – suspected drug dealer.
Apt. raided under pretense that Mincey had purchased drugs –
undercover agent killed.
Guns, ammo, drugs and drug paraphernalia were seized and
admitted as evidence in court.
Mincey was freed - the 4 day search was illegal.
Michigan V. Tyler



Business establishment leased by Tyler and
buisness partner destroyed by fire.
Fire was extinguished, but it was too smoky to
thoroughly search the property…arson was
suspected so several items were seized.
Investigators returned again the next morning, 4
days later, 7 days later and 25 days later.
What
evidence do you think was admissible in court?
ENRIQUE CAMARENA CASE

Complete Case Study
Supreme Court Findings Clear…

If there is time and circumstances permit –
investigators must obtain a warrant before
investigating and retrieving evidence.