Arriving at the Fire and/or Arson Scene: Processing Evidence at the Scene
After documenting the scene, the investigator or other evidence collectors must collect, preserve and store evidence from the scene. He or she should follow these steps:
Note: This section of the guide is intended for the individual responsible for the investigation of a fire incident. At the time the scene is determined to involve an arson or other crime, the investigator must address legal requirements for scene access, search and evidence seizure.
- Identify, collect and preserve evidence.
- Prevent evidence contamination.
- Package and transport evidence.
- Establish and maintain the chain of custody.
Identify, collect and preserve evidence. The investigator should ensure that evidence collectors identify, document, collect and preserve evidence for laboratory analyses, further investigations and court proceedings.
Evidence collectors should:
- Take precautions to prevent contamination.
- Document the location of evidence using written notes, sketches, photographs, photo and video logs, the evidence recovery log, evidence tags and container labels.
- Collect evidence in any areas where the fire originated (such as the first fuel ignited and ignition source) in cases where the fire is not accidental.
- Place evidence in labeled containers for transportation and preservation. Liquid evidence collected for laboratory identification must be immediately placed in clean, unused, vaportight containers (e.g., clean, unused paint cans; glass jars; laboratory-approved nylon or polyester bags) and then sealed.
- Label each container so that it is uniquely identified. Labeling may include the name of the investigator, date and time of collection, case number, sample number, description and location of recovery.
- Collect and preserve suitable comparison samples but recognize that such samples may be unavailable.
- Package evidence in accordance with their laboratories' policies and procedures.
- Recognize the presence of other physical evidence, such as bloodstains, shoe prints, latent prints and trace evidence, and use proper preservation and collection methods or seek qualified assistance.
Prevent evidence contamination. The investigator should control access to the fire scene after fire suppression and see that evidence is collected, stored and transported so that it will not be contaminated.
Evidence collectors should:
- Establish and maintain strict control of access to the scene.
- Recognize that fuel-powered tools and equipment present potential contamination sources and should be avoided. When collectors must use these tools and equipment, the investigator should document their use.
- Wear clean, protective outergarments, including footwear.
- Use clean disposable gloves for collecting items of evidence. (To avoid cross-contamination, gloves should be changed between collecting unrelated items of evidence or when visibly soiled.)
- Use clean or disposable tools for collecting items of evidence from different locations within a scene.
- Place evidence in clean, unused containers and seal immediately.
- Store and ship fire debris evidence containers of evidence collected from different scenes in separate packages.
- Package liquid samples to prevent leakage and ship them separately from other evidence.
- Store and ship fire debris evidence separately from other evidence.
- Follow specific laboratory requests (e.g., to submit an unused sample container).
Note: In cases of accidental fire, evidence should not be needlessly disturbed, but the property owner or insurer should be notified to avoid issues of spoliation.
Package and transport evidence. The investigator should ensure that packaging, transportation and storage procedures are followed to prevent any destructive changes in the condition of samples.
The personnel responsible for packaging and transport should:
- Take precautions to prevent contamination.
- Package fragile items carefully.
- Freeze or immediately transport items containing soil to the laboratory.
- Transport all volatile samples to the laboratory in a timely manner.
- Comply with shipping regulations.
Establish and maintain the chain of custody. The investigator should ensure that the chain of custody is maintained.
Personnel responsible for the chain of custody should:
- Maintain written records documenting the sample number, description of the evidence, date and location where it was found, collector's name and miscellaneous comments.
- Document all transfers of custody, including the name of the recipient and the date and manner of transfer.
- Document the final disposition of the evidence.
