1. Crime Scene Processing
Forensic Science:
Crime Scene Processing

2. Duties of Field Team & Crime Lab
Field Investigative Unit
Crime Lab Scientist
Secure the crime scene
Receive/sign for evidence
Photograph the crime scene
Review paperwork
Search the crime scene
Complete chemical and/or physical tests on evidence
Properly collect and package evidence
Complete an analysis of the findings
Complete proper forms: Evidence Submission & Chain of Custody
Provide expert testimony
Deliver or ship evidence to proper processing site

3. Ordinary vs. Expert Testimony
Ordinary testimony is restricted to statements concerning what the witness actually saw or heard.
An ordinary witness is prohibited from stating opinions about the case and from quoting statements made by other people.
Expert testimony is that given by a specialist who has been recognized by the court as having expert knowledge about evidence in the case.
An expert witness is allowed to express an opinion about the validity of the evidence in a case and may quote the statements of other experts in support of an opinion.

4. Secure & Isolate the Crime Scene
Responsibility of first officer on scene
Get help for injured
Preserve & protect area by roping off
Clear all except essential and authorized persons from crime scene area

5. Separating the Witnesses
Witnesses must not be allowed to talk to each other.
The following questions need to be asked of each witness:
When did the crime occur?
Who called in the crime?
Who is the victim?
Can the perpetrator be identified?
What did you see happen?
Where were you when you observed the crime?

6. Record the Scene Required for trial Common methods:
Photography – always display a scale, from many angles
Sketches – Rough & Finished
Notes - Ongoing throughout the process
Photographs & a rough sketch must be completed before any evidence is collected or searched for.

7. Sketches: Must include: Outline of room
Location of doors, windows, & furniture if inside trees, vehicles, hedges & other structures if outside
Positions of all recovered items of physical evidence.
All objects should be measured from two immovable landmarks.
Name of illustrator, date, compass rose, scale, & legend for physical evidence

8. Sketch, cont.

9. Sketches, cont.

10. Types of Crime Scenes
There may be more to a crime scene than first meets the eye. In fact, more than one crime scene may exist, depending upon how the crime was committed — not to mention where.
Crime scenes therefore are considered either primary or secondary.
The primary crime scene is where a crime actually occurred.
A secondary crime scene is in some way related to the crime but is not where the actual crime took place.
In a bank robbery, for example, the bank is the primary scene, but the get-away car and the thief's hideout are secondary scenes.
In the case of a killer who commits a murder in someone's home but transports the victim's body to a river for disposal, the victim's home is the primary scene, and the killer's vehicle and the point along the river where the body was dumped are secondary scenes.

11. Search the Scene All areas including entry & exit points
Method choice depends on type of crime & size/location of crime scene

12. Method Size/Location Type of Crime Quadrant or Zone
Building or other structure
Homicide, home invasion, robbery, sexual assault,…
Spiral
Large area, no barriers, open field
Kidnapping, homicide,…
Strip or Line
Large area looking for large object in a single direction
Plane crash, …
Grid
Large area looking for large object in two directions
Arson, …

13. Collect & Package Physical Evidence
Physical Evidence: any and all objects that can establish that a crime has been committed or can provide a link between a crime, victim, and/or perpetrator.
Must be handled in a way that prevents any change from scene to lab.
Common examples of physical evidence:
Fibers/clothing
Paint chips, broken glass or chemicals
Hair
Body fluids
Bullets
Soil
Fingerprints
Shoe or tire tracks
Tool marks
Not a comprehensive list

14. Evidence, cont.
Must be placed in separate containers to prevent cross-contamination
Maintain chain of custody (a list of all persons who came into possession of an item of evidence)
Obtain controls (physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence)
Submit evidence to laboratory

15. Evidence Submission Form
NOTE:

16. Chain of Custody Form
Chain of Custody

17. Legal Considerations at Crime Scene
Under the Fourth Amendment to the United States Constitution, most searches by the police require a search warrant based on probable cause, although there are exceptions.
Any police entry of an individual's home always requires a warrant (for either search or arrest), absent exigent circumstances, or the free and voluntary consent of a person with reasonably apparent use of or control over the property.

18. Legal Considerations at Crime Scene
4th Amendment: The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated; and no Warrants shall issue but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

19. Probable Cause
In terms of seizure of items, probable cause merely requires that the facts available to the officer warrants a "man of reasonable caution" to conclude that certain items may be contraband or stolen property or useful as evidence of a crime.

20. Search Warrants
A search warrant is a court order issued by a Magistrate, judge or Supreme Court Official that authorizes law enforcement officers to conduct a search of a person or location for evidence of a crime and to confiscate evidence if it is found.
Officers must have a search warrant or they must have one of the exceptions to the Search Warrant Rule.

21. Exceptions to the Search Warrant Rule
Search subsequent to arrest
Existence of emergency circumstances
Plain View
Consent
Stop & Frisk/Terry Pat Down
Inventory
Need to prevent the immediate loss or destruction of evidence
Administrative
Border
Hot Pursuit