1. Forensic Science
The Crime Scene

2. Crime Scene Investigation
Purpose: to help establish what happened (crime scene reconstruction) and to identify the responsible person.
Investigators must:
carefully document the conditions at a crime scene
Recognize and collect all relevant physical evidence
Determine the full extent of a crime scene.
The law enforcement officer who protects and searches a crime scene plays a critical role in determining which pieces of physical evidence will be used in solving or prosecuting violent crimes.

4. The Crime Scene A place where a crime has taken place.
A starting point for a criminal investigation.
There is no "crime scene exception" to the Fourth Amendment (illegal search and seizure)
If the scene is a protected area such as a house or private part of a business, then a search warrant or consent must be obtained. 

5. Processing the Crime Scene
There are 7 steps to processing a crime scene
Secure and Isolate the Crime Scene
Record the Scene Photograph, Sketch, Take Notes
Conduct a Systematic Search For Evidence
Collect and Package Evidence
Maintain Chain of Custody
Obtain Controls
Submit Evidence to the Laboratory

6. Law Enforcement Personnel on the scene
In order for physical evidence to be analyzed and to tell its part of the story, it must first be properly collected.
In order for the proper collection to take place, the crime scene, must be properly secured, protected, and preserved.
This scene security, protection, and preservation is the responsibility of any and all law enforcement personnel who come in contact with the scene, the suspect, and/or the victim.

7. Crime Scene Investigation Team
Team Leader
Photographer and Photographic Log Recorder
Sketch Preparer
Evidence Recorder/Evidence Recovery Personnel
Specialists

8. Crime Scene Search Patterns
To locate, identify, and collect any tangible material which may be associated with a suspect and/or victim
Standard search patterns: spiral, grid, strip or line, and quadrant or zone search
Important things to do during a search:
Search from the general to the specific for evidence.
Be alert for all evidence.
Search entrances and exits.
Discuss the search with all personnel.
                            
                            
                            

9. Recording the Crime Scene
Includes transient details such as lighting (on/off), drapes (open/closed), weather, or furniture moved by medical teams.
The scope extends to possible arguments which might be made in this case (suicide/self defense) and documenting conditions supporting or refuting these arguments.
Important to recognize what should be present at a scene but is not (victim's vehicle/wallet) and objects which appear to be out of place (ski mask) and might have been left by the assailant.

10. Photographer/Photographic Recorder
Photograph entire area before it is entered.
Photograph victims, crowd, and vehicles.
Photograph entire scene with overall, medium and close-up coverage, using measurement scale when appropriate.
Photograph major evidence items before they are moved
Photograph all latent fingerprints and other impression evidence before lifting and casting are accomplished.
Prepare photographic log and sketch.

11. Photographing the Crime Scene
Film is cheap; you can never take too many pictures.  Utilize a flash if necessary.
Move evidence for better photographs only after the "as is" photograph has been taken and is necessary for additional identification.

12. Sketch Preparer
Diagram immediate area of scene and orient diagram with sketch.
Show major items of evidence on sketch.
Designate and label areas to be searched and advise team leader and all other search members of designated search areas.
Obtain assistance for taking measurements and double check measurements.
Ensure necessary administrative information, such as scale disclaimer (not drawn to scale), is recorded on sketch.

13. Sketching the Crime Scene
Documentation of physical evidence locations, as well as measurements showing pertinent size and distance relationships in the crime scene area.

14. Evidence Collector/Custodian
Have significant evidence photographed before collection.
Describe evidence and its location on appropriate bag or envelope.
Sign and date evidence container/maintain chain of custody.
Appropriately collect and package evidence to maximize evidence integrity.
Maintain evidence log.
Use appropriate protective equipment (gloves) and methods when dealing with potentially infective evidence (blood).

15. Collecting Physical Evidence
Any collected evidence should have its location and condition documented before it is removed
Evidence should be collected in appropriate containers, wearing gloves
Containers/envelopes should be sealed with tamper-proof tape
Seals should be signed
Chain of Custody must be maintained

16. Information On Evidence Packaging
The following information should be included on evidence packaging:
Location of crime scene
Location of evidence at scene and time of collection
Personnel who collected the evidence
Condition of item at time of collection
Chain of Custody log

17. Specialists
The field of forensic science is so broad today that no agency will have every form of specialty service available from among its ranks.
Typically, specialists are brought in from industry, the academic community, private scientific laboratories, and similar concerns.
Some items to consider when dealing with outside specialists:
The competence and reliability of the specialist.
The ability of the specialist to work at a scene within law enforcement guidelines.
The role of the specialist in presenting expert testimony in court.

18. Obtaining Controls from the Crime Scene
Controls are physical evidence whose origins are known, such as carpet fibers from a suspects home, that can be compared to crime scene evidence.
The crime lab must have a thorough sample of control materials for comparison.

19. Submitting Evidence to the Crime Lab
Evidence can be submitted to the crime laboratory by a crime scene investigator personally or via the mail
Chain of Custody must be maintained at all times
Many labs require specific documentation before they will process evidence
Evidence evaluated by the lab may take a long time to process, or be held due to back log.