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2. Crime Scene Investigation
Forensic Science
Warm-up Who Dunit!!!

3. Crime Scene Vocabulary
CRIME SCENE: Any physical location in which a crime has occurred or is suspected of having occurred.
PRIMARY CRIME SCENE: The original location of a crime or accident.
SECONDARY CRIME SCENE: An alternate location where additional evidence may be found.
SUSPECT: Person thought to be capable of committing a crime.
ACCOMPLICE: Person associated with someone suspected of committing a crime.
ALIBI: Statement of where a suspect was at the time of a crime.
Source:

4. What will evidence collected at a scene do for the investigation?
Types of Evidence
Testimonial evidence includes oral or written statements given to police as well as court testimony by people who witnessed an event.
Physical evidence refers to any material items that would be present at the crime scene, on the victims, or found in a suspect’s possession.
Trace evidence refers to physical evidence that is found in small but measurable amounts, such as strands of hair, fibers, or skin cells.
What will evidence collected at a scene do for the investigation?
May prove that a crime has been committed
Establish key elements of a crime
Link a suspect with a crime scene or a victim
Establish the identity of a victim or suspect
Corroborate verbal witness testimony
Exonerate the innocent.
Give detectives leads to work with in the case
Source:

5. Crime Scene Personnel
POLICE OFFICERS are typically the first to arrive at a crime scene. They are responsible for securing the scene so no evidence is destroyed and detaining persons of interest in the crime.
The CSI UNIT documents the crime scene in detail and collects any physical evidence.
The DISTRICT ATTORNEY is often present to help determine if any search warrants are required to proceed and obtains those warrants from a judge.
The MEDICAL EXAMINER (if a homicide) may or may not be present to determine a preliminary cause of death.
SPECIALISTS (forensic entomologists, anthropologists, or psychologists) may be called in if the evidence requires expert analysis.
DETECTIVES interview witnesses and consult with the CSI unit. They investigate the crime by following leads provided by witnesses and physical evidence.
Source:

6. Adapted from http://www.feinc.net/cs-proc.htm
Crime Scene Protocol
Step 1: Interview
The first step in investigating a crime scene is to interview the first officer at the scene or the victim to determine what allegedly happened, what crime took place, and how was the crime committed. This information may not be factual information but it will give the investigators a place to start.
Step 2: Examine
The second step in the investigation of a crime scene, which will help identify possible evidence, identify the point of entry and point of exit, and outline the general layout of the crime scene.
Step 3: Document
The third step in the protocol involves creating a pictorial record of the scene as well as a rough sketch to demonstrate the layout of the crime scene and to identify the exact position of the deceased victim or other evidence within the crime scene.
Step 4: Process
This is the last step in the protocol. The crime scene technician will process the crime scene for evidence, both physical and testimonial evidence. It is the crime scene technicians responsibility to identify, evaluate and collect physical evidence from the crime scene for further analysis by a crime laboratory.
Adapted from

7. Source: http://www.isp.state.il.us/forensics/
Investigating the Evidence
Drug Chemistry – Determines the presence of controlled substances and the identification of marijuana
Trace Chemistry - Identification and comparison of materials from fires, explosions, paints, and glass.
Microscopy – Microscopic identification and comparison of evidence, such as hairs, fibers, woods, soils, building materials, insulation and other materials.
Biology/DNA – Analysis of body fluids and dried stains such as blood, semen, and saliva.
Toxicology – Tests body fluids and tissues to determine the presence of drugs and poisons.
Latent Prints - Identification and comparison of fingerprints or other hidden impressions from sources like feet, shoes, ears, lips or the tread on vehicle tires.
Ballistics (Firearms) – Study of bullets and ammunition through the comparison of fired bullets, cartridges, guns, and gunpowder patterns on people and objects.
Toolmarks – Examines marks left by tools on objects at a crime scene or on a victim, such as a hammer used to break a door or a screwdriver used to pick a lock.
Questioned Documents - Examination of documents to compare handwriting, ink, paper, writing instruments, printers, and other characteristics that would help to identify its origin.
Source:

8. What evidence would you collect?
Mock Crime Scene:

9. 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

10. 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

11. 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

12. 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

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

14. 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

15. 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

16. 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

17. Example: Final Sketch

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

19. 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

20. 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

21. 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

22. 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

23. 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

24. 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

25. 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

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

27. 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

28. 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

29. 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

30. druggist fold (get paper)
Practice using a piece of notebook paper.

31. 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

32. 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

33. 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)

34. 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.