A Guide for Investigating Bomb and Explosion Scenes: Processing Evidence at the Scene
Note: At the time the scene is determined to involve a bombing or other crime, the investigator must address legal requirements for scene access, search and evidence seizure.
The lead investigator must assemble an evidence processing team to collect and process evidence found at the scene. He or she should follow these steps:
- Assemble the evidence processing team.
- Organize evidence processing.
- Control scene contamination.
- Identify, collect, preserve, inventory, package and transport evidence.
Assemble the evidence processing team. The lead investigator should organize an effective evidence processing team that includes the following experts:
- Bomb disposal technician.
- Evidence custodian.
- Forensic specialist.
- Logistics specialist.
- Medical examiner.
- Photographer (still, digital, video, etc.).
- Procurement specialist.
- Safety specialist (structural engineer, etc.).
- Sketch artist.
Organize evidence processing. The investigator must organize evidence collection and preservation efforts — regularly evaluating the scene, adapting to changes, and briefing the investigation team.
Before deploying the team, the investigator should:
- Review and reevaluate:
- The boundaries of the scene.
- Safety concerns.
- Command post and staging locations.
- Evidence processing and storage locations.
- Personnel and equipment requirements.
- Legal and administrative considerations.
- Identify the search procedure for the scene.
- Ensure that transient physical evidence has been preserved and collected.
- Detect onsite explosives (e.g., trace explosives detection, use of canines, chemical tests), using qualified personnel.
- Brief the team and review assignments.
Control scene contamination. The lead investigator must make sure that scene and the evidence collected are not contaminated, and must make sure personnel are safe.
The investigator should ensure that evidence processing personnel:
- Use clean protective outergarments and equipment for each scene.
- Obtain control samples as needed (e.g., evidence containers, swabs of equipment and personnel).
- Package collected evidence in a manner that prevents loss, degradation or contamination.
- Package, store and transport evidence from different scenes or searches in separate external containers.
Identify, collect, preserve, inventory, package and transport evidence. The investigation team should search for physical evidence that establishes that a crime was committed, and link elements of the crime to possible suspects.
To maximize the recovery and evaluation of all types of physical evidence, the investigator should:
- Prepare an evidence recovery log that documents:
- Item number.
- Location found (grid number if used).
- Collector's name.
- Markings (either directly on the item or indirectly on the package).
- Packaging method.
- Miscellaneous comments.
- Identify evidence by:
- Assigning personnel to designated search areas.
- Initiating scene-specific search pattern(s) and procedures, including examining immobile structures for possible evidence.
- Attempting to determine the method of bomb delivery.
- Establishing the seat(s) of the explosion(s).
- Documenting blast effects (e.g., structural damage, bent signs, thermal effects and fragmentation).
- Examining the crater, vehicles, structures, etc.
- Documenting the victim location(s) before and after the explosion.
- Ensuring that victims are examined for bomb component fragments. Autopsies should include full-body x-rays.
- Collect evidence, including:
- Suspected bomb components and fragments, including those recovered from victims.
- Suspected materials used to construct and transport the explosive device(s) (e.g., tape, batteries, manuals, vehicles).
- Crater material.
- Residues and other trace evidence (using swabbing techniques).
- Additional items of evidence (e.g., blood, hair, fiber, fingerprints, tire tracks, weapons, documents and, tools).
- Comparison samples of indigenous materials.
- Make sure evidence is:
- Packaged and preserved in containers.
- Labeled (e.g., date, collector's initials, item number and location).
- Recorded in the evidence recovery log.
- Secured in the designated storage location.
- Label, transport and store evidence by:
- Placing evidence from different locations or searches in separate external containers.
- Labeling evidence for storage and shipment, and identifying hazards.
- Arranging to transport the evidence.