Crime Scene Search, Collection, and Handling Notes

Search and Secure Evidence

• The last important step of crime scene investigation is searching for and collecting the evidence. While a lot of evidence is found during the initial walkthrough, additional evidence may have been overlooked or require special processing to reveal it.

• Goal of the search: ensure that all relevant evidence is discovered, documented, and collected.

• Lead investigator determines the search strategy based on the location and the number of officials available to aid in the search.

• Principle: Thorough search of a crime scene helps ensure that all relevant evidence will be recognized, documented and collected.

• Policy: The investigator(s) in charge shall consider different search strategies for crime scenes depending upon locale and the number of officials available to aid in searching.

• Procedure: There are four types of search methodology that can be considered to search a crime scene:

  • Lane or strip search

  • Grid search

  • Zone Search

  • Spiral search

• General Considerations:

  • The size of the lane of the search should be approximately the arms’ length of the searcher.

  • As the search of an area is completed, some marking should be made to indicate that the area has been completed.

  • A mechanism should exist for the circumstance when potential evidence is found (e.g. who is called over, what path they should take, whether the other searches should halt moving until this finding is resolved).

• Figure 1. A Zone Search involves dividing the area to be searched into adjacent zones. The smaller the size of the zone, the more methodical the search can be. Zone searches may be done by multiple searchers per zone.

• Figure 2. Lane or Strip Searches are accomplished by the searchers walking in parallel along defined lanes in the same direction.

• Figure 3. A Grid Search is a lane search that is conducted by completing a lane search in one direction and then completing a lane search in a perpendicular direction. While it takes twice as long as a lane search, it provides a more thorough search of an area.

• Figure 4. A Spiral Search involves a spiral into (inward) or out from (outward) a crime scene. A practical disadvantage with outward spiral searches is the evidence may be destroyed as the searchers move to the center of the crime scene area to begin their outward search.

Collection and Handling of Evidence

• After evidence has been thoroughly documented, it is collected.

• Most items are placed in both a primary and secondary container. The type of container and subsequent storage will depend on the type of evidence collected.

• Methods of collecting and storing evidence will be discussed later in this course.

• The evidence is sealed with tape and the tape is initialed by the collector.

Labeling and Chain of Custody

• All evidence should be labeled to tell where the item was found, the case number and the date and signature off all persons involved in the collection of this evidence.

• This documentation begins the chain of custody for that piece of evidence.

• From that point forward, each person who has contact with the evidence will sign the chain of custody.

Steps of Investigating a Crime Scene

• Secure the Scene

• Separate the Witnesses

• Scan the Scene

• See the Scene

• Sketch the Scene

• Search for Evidence

• Secure and Collect Evidence

• The seven steps are presented as a sequence to guide systematic processing of a scene.

Crime Scene Locations and Time: General Considerations

• While the general procedure remains the same, the location and time of day at which investigators arrive at a scene will affect the way in which each of these steps are carried out.

• Outdoor crime scenes are particularly susceptible to loss, contamination, and deterioration of physical evidence due to environmental conditions — heat, cold, rain, snow, and wind.

• Evidence that cannot be protected should be collected, even if the other steps have not yet been completed.

• Outdoor crime scenes can expand over very large areas. Establishing and documenting the exact location of the scene can be difficult. Investigators may fix the GPS coordinates to a permanent fixed object or, in the case of an open field, place a fixed object like a steel survey pin to mark their location.

Nighttime outdoor scenes

• Outdoor nighttime crime scenes are difficult to document.

• Even with proper lighting for photographs, investigators may miss evidence or accidentally destroy it.

• If possible, outdoor crime scenes should be secured and processed in daylight hours.

Transportation-related cases

• In crimes involving transportation, the evidence will not be isolated to the vehicle itself.

• Investigators should look for impressions of shoe prints leading to or away from the scene.

• There may also be items that were dropped or deposited as the suspect approached or fled from the scene, such as cigarette butts.

• The vehicle involved may be transported to the laboratory after proper documentation.

Indoor scenes

• Indoor crime scenes are the easiest to secure and protect, but are still susceptible to loss and contamination.

• As various first responders, patrol officers, and investigators enter and exit the scene, they could contaminate evidence.

• Limiting the number of people on the scene, documenting everyone who enters the scene, and establishing a clear path for traffic flow within the scene will decrease the loss of evidence.