1. Crime Scene Investigation
Forensic Science

2. Process a Crime Scene Isolate and secure the scene Document the scene
Search for evidence
Collect and package the evidence while maintaining the chain of custody
Submit the evidence for analysis

3. First Officer on the Scene
A – Assess the crime scene and assist the injured D – Detain the witness(es) A – Arrest the perpetrator P – Protect the crime scene T – Take notes

4. Secure the Crime Scene Look for signs of life
Cordon off the scene (only allow authorized personnel in)
Bodies should be certified as “dead” by a medical examiner (ME) before being moved

5. Survey the Crime Scene
A walkthrough is performed by the crime scene investigator, the first officer, and sometimes the lead detective
Record initial observations of who, what, where, when, and how
Make a plan of action

6. Document the Crime Scene
Record the crime scene and potential evidence with
Notes
Photography
Sketches
Videography

7. Notes
Record the following while at the crime scene (details are the key):
Date
Time
Description of the location, weather, and environmental conditions
Description of the crime
Location of the evidence relative to other key points
Names of all people involved
Any other relevant information

8. Photography Nothing should be moved until photographed
Take photos of the scene and the surroundings
Photograph entrances and exits
Take wide and close-up photos
Use various angles for each piece of evidence
Use a ruler to show size

9. Sketches
Draw a rough sketch at the scene (reconstruct it better later)
Include
Date, time, and location
Scale
Recovered items
Important features
Accurate distance measurements of objects (from two fixed points)
A legend for description of items
A compass designating north
Names of investigators, victims, and suspects

10. Example: Final Sketch

11. Videography Narrate the video Be objective
Record from different perspectives

12. Measuring Techniques Triangulation
For each piece of evidence being recorded, use two permanent objects as reference points that are not likely to be moved
The two reference points and the piece of evidence form a triangle, hence the term triangulation
Whatever object you are measuring to or from, use the same spot on the object every time

13. Measuring Techniques (continued)
Rectangular Coordinates – Baseline
The simplest form of the rectangular coordinate system
Using a straight line between two known points, items are measured along the line and then measured perpendicular to the line
Inside or outside of a house, this line can be a straight wall
Outdoor scenes can use a string or long measuring tape as the reference or baseline

14. Measuring Techniques (continued)
Rectangular Coordinates – Grid
Measure the distance of items from two perpendicular baselines
This technique is particularly appropriate in a room with perpendicular walls or outdoors with perpendicular streets

15. Measuring Techniques (continued)
Polar Coordinates
Measure both the distance and the direction (angle) an object is from a known reference point
For example, 40 feet from the edge of the house and 15 degrees east of north

16. Search the Crime Scene
When searching a crime scene, wear the following, if available, to minimize contamination
Disposable gloves
Masks
Coveralls with a hood
Slippers

17. Search Patterns
Depend on the size and the location of the crime scene and the number of investigators available
Stick to one pattern and one supervisor
Better to collect everything and not need it than fail to collect something and need it later

18. Search Patterns (continued)
Spiral – may move inward or outward; best used where there are no physical barriers
Grid – basically a double-line search; effective, but time-consuming
Line (Strip) – best in large, outdoor scenes
Zone (Quadrant) – most effective in houses or buildings; teams are assigned small zones for searching

19. Search Patterns (continued)
Spiral
Grid
Quadrant or Zone
Strip or Line

20. Collect & Package Evidence
Physical evidence must be packaged and collected before time and weather can alter it
Physical evidence – any object that can establish that a crime has been committed or links a crime and the victim or suspect
The Golden Hour – the window of opportunity to collect time-sensitive information or evidence

21. Collect & Package Evidence (continued)
Each item must be placed in a separate container, and sealed and labeled
The most fragile evidence is collected and packaged first
Different types of evidence require specific or special collection and packaging techniques
The body is the property of the coroner or medical examiner; collection of evidence on the body is done by that department

22. Collect & Package Evidence (continued)
Containers such as vials, envelopes, plastic bags, paper bags, canisters, and cardboard boxes are good packaging devices
Most items should be placed in a primary container and then in a secondary container
Trace evidence may be placed on a piece of paper which is then folded in a “druggist fold” and placed in a secondary container

23. Collect & Package Evidence (continued)
Containers should be sealed with tamper proof tape, and dated and initialed
Each package should contain
Date, time, and location
Case number
Agency and collector’s name
Victim’s name(s)
Description of contents
Never package two items from two different sources or locations

24. Chain of Custody
There must be a written record of all people who have had possession of an item of evidence, beginning at the time of collection
Every person who handled or examined the evidence must be accounted for
Chain of Custody should include
Date and time of transfer
Location of transfer
To/From names
Purpose of the transfer

25. National Databases
Crime Scene Investigators can submit evidence for analysis to several national databases based on the type of evidence
Examples include
Automated Fingerprint Identification System (AFIS)
Integrated Automated Fingerprint Identification System  (IAFIS)
Combined DNA Index System (CODIS)
Integrated Ballistics Identification System (IBIS)
International Forensic Automotive Paint Data Query (PDQ)

26. Resources
, Saferstein, Richard. Forensic Science: An Introduction. New Jersey: Pearson Prentice Hall, 2008.
, Ball-Deslich, Barbara and John Funkhouser. Forensic Science for High School. 2nd Edition. Kenall/Hunt, 2009.