L2.1 Crime Scene Investigation

The primary crime scene is the original crime scene while the secondary crime scene is the location after the crime scene. An example of a primary crime scene is the house in which a murderer committed a crime in, and an example of a secondary crime scene is the location the body in which the murderer moved it to like a dumpster.

• Macroscopic - broader/bigger view of crime scene

  • Ex. house 

• Microscopic - where evidence related to crime scene is found 

  • Ex. room in a house

1. Assist victim

2. Search (and arrest) for suspect if still in the scene

3. Protect and secure the scene using barrier tape, official vehicles, etc.

• Create logs of whoever leaves/enters the scene. Do not allow unauthorized people to enter/contaminate the scene.

• Note and communicate all changes/movements made to the scene.

4. Separate and secure witnesses

5. Search for and preserve evidence

• Linkage of people, scenes or objects

• Information on the corpse

• Witness statements

• Identification of suspects

• Identification of drugs or alcohol

• Reconstruction of crime

• Information of corpus delicti

• Information on modus operandi

1. Photography 

   1. Recorded in a photo log and can be used in imaging technology to map out a crime scene

2. Notes 

   1. Who, what, where, when, why 

   2. notification info, arrival info, scene description, victim description, and crime scene team

3. Videography 

   1. Use a placard that includes necessary info (time, date, case number, etc..)

   2. Begin with the scenes surroundings and videotape the orientation of evidence

   3. Record the victim’s viewpoint

   4. Recordings are used as evidence and should not be edited.

4. Sketching 

   1. Final documentation step

   2. Two most common perspectives: overhead/birds-eye view and elevation/side view

   3. Three techniques used to obtain measurements: triangulation, baseline, and polar coordinates

The survey is used to track any evidence before the documentation process. Information that helps with the reconstruction of the scene, includes immediate processing/protection, points of exit/entry, and initial observations.

Search Method

How is it conducted?

Where is it best used? (consider pros and cons)

Link Method

One type of evidence leads to the next item

large, small, outdoor, and indoor scenes

Line/Strip Method

-Scene is divided into parallel strips

-Searchers walk straight on their “line” in order to scan their specific area

large, outdoor areas

Grid Method

Searchers overlapping lines, but time consuming 

large fields

Zone Method

-scenes with defined zones/quadrants

-Teams are assigned a zone where they usually use another method. 

houses or buildings

Wheel/Ray Method

used in only specific occasions and have limited application

small and circular scenes with little obstacles

Spiral Method

Inward or outward spiral, has limited application

crimes scenes with no physical barriers (outdoor/open water)

Transient, fragile, or easily lost evidence is collected first. Evidence is packaged into a primary container that is placed inside a secondary container. Evidence tape then completely covers the opening of the outer container and is marked with the initials of the collector.

1. Data collection

2. Conjecture (possible explanation of what happened at the crime scene)

3. Hypothesis formulation

4. Testing

5. Theory formulation