This brings us to another basic investigative principle that often gets overlooked at fire scenes: attempting to identify or lift latent prints in what is believed to be the "point of entry" (POE) if there were signs of forced entry in a residence or building that caught fire. Dusting for latent prints should always be attempted unless the POE was heavily damaged by the fire.
In a desolate area or an open field, tire tracks may have also been left behind that can possibly identify the type of vehicle that had been present at the scene.
Sometimes residences or businesses in the immediate area have video cameras. These can capture a glimpse of a vehicle or suspect involved or even what initially caused the fire. If enough evidence is captured on video, there may no longer be a need for an in-depth police investigation.
Consent to Search
At the scene of the fire, a firefighter or ranking fire official may request to take you on a "walk-through" of the scene to explain his or her observations that led to the conclusion that the fire was arson.
Before you go on that walk-through, remember that law enforcement officers must have the legal authority to enter and investigate the scene after the fire is out. Many courts have allowed an "exigency exception" and determined that a warrant is not necessary. But when in doubt, consult your agency's legal liaison or local prosecutor's office before going into the building without a warrant or consent after the fire is out.
Obtaining "consent to search" in either a written or audiotaped format is a good idea even if the property owner legitimately appears to be a "victim." Always remember that evidence gathered may be used to convict the property owner or resident of insurance fraud or other crimes. The "victim" may become a "suspect" later.
Don't Be a Casualty
And when entering, remember to consider everyone's safety. Safety is and always will be the first priority.
Make sure that a qualified professional has turned off all utilities. If the building you're investigating is heavily damaged from the fire, consider having a building inspector evaluate the stability of the structure before entering it.
Never go in alone. If circumstances provide no choice, make sure that someone knows where you are and have them check on you regularly in the event that something does happen. Fire scenes can be very dangerous, even long after the fire has been put out.
Roofs can cave in, chimneys can collapse, and walls and/or ceilings that have been knocked down can contain nails or other sharp objects that can penetrate boots or shoes. Wear safety boots with steel toes and protective shank soles to prevent puncture wounds. Always wear proper safety equipment, including a helmet or OSHA-approved hard hat to protect against falling debris.
Inhalation of smoke or toxic fumes, electrical shock, or hazmat-related risks (depending on the contents of the building) are also dangerous.
Before entering, make sure that the fire scene has been well ventilated to reduce the risk of carbon monoxide poisoning or other inhalation hazards. Toxic fumes can be odorless, tasteless, and colorless—and they can be deadly.
Fire crews often have industrial size fans or other ventilation equipment they can set up and operate before you go in. It is also a good idea to keep an OSHA-approved particle filter dust mask or High Efficiency Particulate Air (HEPA) filter with you for these situations. Separate stackable cartridges can be added to an air-purifying respirator to protect against toxic gases.
Also, you will want to wear OSHA-approved eye and/or splash protection. Contaminated water from the fire suppression efforts, mixed with potentially toxic contents of that building, can drip or run off from above and get into your eyes. If these basic but essential safety items are not available, ask to borrow them from the fire suppression crew at the scene (who are no longer wearing them).
When entering the fire scene, determine if it is safe and/or possible to walk from the least to the most burned areas and document them accordingly. Take note of the fire's progression by describing burned areas as well as the surrounding or adjacent areas that may only have indirect heat or smoke damage. Each area and its unique burn patterns need to be photographed or videoed as evidence and for future evaluation by others who specialize in fire/burn pattern analysis.
Be sure to include electrical outlets in the area(s) around the most fire damage (possibly the origin of the fire), and the breaker box and switches. Make note of any "tripped" switches, wiring and/or connections (electrical, phone, cable, etc.) leading to the building, as well as gas meters and any other external devices connected to the building (A/C or HVAC unit). Photograph and document any electrical items (all angles) and the outlets they are plugged into within the burned area or areas, if the origin cannot be initially
Prepare to identify, collect, and preserve evidence from the fire scene as you would for any other incident or crime. However, there are some factors to consider when collecting evidence from a fire, since certain items may need to be evaluated by laboratory personnel. Make sure to send those items to the laboratory immediately following the incident.
Items suspected of having an ignitable liquid accelerant on or in it will need to be preserved in a container that traps chemicals and vapors, including wet or dry samples. Evidence "paint cans" will work well. If the item or items will not fit into cans, seal them in a large static free "k-pack" bag, but make sure to read about the specific product's instructions and limitations.
There are also additional considerations on how evidence "paint cans" can be stored prior to their use. If cans are in the trunk of a vehicle, make sure they are clean and unused, and tightly sealed in k-pack bags.
In court, the defense will probably not be able to challenge the lab results. However, they may challenge or try to create doubt about the state of the cans before evidence was collected. If the cans are stored in the trunk of a car, the defense may attempt to persuade the jury that the cans were exposed to the vehicle's
Avoid possible "cross contamination" on items that are being held or preserved for lab analysis. Change your latex gloves every time you handle a new evidence sample. Also, be sure to consider what your boots could be tracking around. If you are wearing them every day during patrol (as most officers do), there is a possibility the defense may suggest that your boots could have been exposed to ignitable liquids prior to the fire while fueling your vehicle. Thoroughly wash your boots before entering a fire scene. Dawn dishwashing liquid is commonly used by fire investigators—it eliminates grease and petroleum-based residue.
Fire scenes can draw other people who have a potential vested interest in the scene.
Often, insurance adjustors or private investigators may arrive at the scene to do their own investigation and analysis on behalf of their organization or employer.
When in doubt, do not allow them access if the scene is being investigated (as with any criminal investigation). However, insurance company fire investigators often bring a vast amount of experience, knowledge, and specific training. They will often agree to pay for lab analysis at an agreed-upon neutral third party laboratory. For smaller police agencies with minimal budgets, this can be a great thing. Just keep in mind that they work for someone who stands to potentially lose a lot of money. Power and/or gas companies may also send out a technician or investigator to ensure that the fire was not caused by their equipment or error.
Document and convey all potential hazards discovered on scene to the owner and/or person responsible. One or two simple sentences citing your findings could protect you and your agency from liability if the owner or his or her agent gets hurt after the scene is turned back over.