Using infrared goggles, digital cameras and fine-hair brushes, they are photographing shoe prints and vehicle tracks, interviewing witnesses and digging through ashes in search of ignition devices. At least four of the major fires in the region are considered arson or suspected arson, authorities said. No arrests have been made, but a possible suspect has been identified in one of the Ventura County blazes and a hunter has been cited for allegedly igniting the Cedar fire in San Diego.
In San Bernardino County, witnesses told investigators about a van that was seen leaving the area where the Old fire began and about a suspicious person on a motorcycle near where flames were first spotted in the Grand Prix fire.
Despite the meticulous work of investigators, many arson fires are never solved. Even fewer cases are actually taken to court. Contributing to the problem is the scarcity of witnesses and forensic evidence. What does exist -- ignition devices, magazines, matches -- may have burned in the fire.
They also plan their actions, looking for thick brush and lightly traveled areas. Brown Jr. But anyone who may have been in the area at the time a fire started can be crucial, helping investigators determine where a fire began or who might have been responsible. An investigation typically begins by attempting to establish the point of origin, in an area where dozens of acres of earth can be scorched within minutes.
Investigators scour charred ground -- often on their hands and knees -- in search of clues. Forest Service wild land fire investigator. It starts cooler and goes out hot, leaving heavier scarring as it progresses. In determining whether the fire was arson, investigators look for crude ignition devices, such as a matchbook left to burn with a rock placed on top or a can with an incendiary concoction of brake fluid, aluminum foil and chlorine inside.
Dogs sniff for kerosene or lighter fluid, and investigators collect dirt clumps in plastic bags. DNA evidence can be obtained from burned-out cigarette butts at the scene, and fingerprints can be lifted from discarded beer bottles or soda cans.
Water contains oxygen. If the fire is hot enough which grease fires often are , the water, rather than putting the fire out, vaporizes into flammable gases that actually provide fuel in the form of oxygen and hydrogen gas molecules. For this reason, the best way to put out a kitchen grease fire is to place a lid over the pot or pan on fire and cut off the oxygen to the blaze.
One of the other key ingredients to a combustion reaction is the fuel or hydrocarbon molecules molecules made up of hydrogen and carbon like octane in the combustion reaction.
One of the best ways to stop a fire from spreading or starting in the first place is to remove the fuel. In an active fire this means removing any flammable materials from its path. Firemen do this in forest fires by cutting trenches called "fire breaks" that are devoid of plants or other organic materials. Before a fire starts this would mean removing any flammable materials or putting a non-flammable space between combustible materials and the population.
In fires that burn at lower temperatures than a grease fire, water in sufficient amounts will extinguish the flame. This process is called cooling and essentially extinguishes the fire by removing the "spark" necessary to keep the reaction going. The cooling of the temperature lowers the overall energy of the reaction until it cannot make it over the activation barrier. These chemicals work by creating a non-flammable coating on the surface of the area on fire and breaking the chain reaction of the fire.
This is actually another way of starving the fire since the coating essentially removes the fuel from the path of the fire. So now we know how a fire works chemically and how to extinguish a fire by combating those properties that make it burn, but how do we distinguish arson from other forms of fire?
Arson is the criminal setting of a fire to commit at least vandalism and at worst murder or even mass murder. Arson is difficult to investigate for three main reasons:. Investigating arson is therefore limited to finding the chemicals left at the scene and identifying them as well as reconstructing the path the fire took to find areas of ignition and patterns in the arsonist's methods.
To determine if a fire has been started by an arsonist, the arson investigator needs to begin examining a fire scene for signs of arson as soon as the fire has been extinguished.
Looking for accelerants is the first step. Evidence of arson is nearly impossible to preserve. Not only will the fire likely destroy physical proof but the water and chemical foam used to put out the blaze can also destroy potential evidence. The investigator will ask firefighters for details such as the color of the smoke, damaged sprinkler systems, condition of doors and windows, and general strange behavior of the flames. After establishing the behavior of the fire, investigators will look for point of origin and any other physical evidence that can be documented.
This allows them to reconstruct the event and use the scientific method to prove or disprove arson. When examining arson, one of the biggest factors is motive. An investigator will look for one of these factors when considering whether someone committed arson:. You or someone in your family has been accused of arson. A qualified arson investigator can arm you with evidence that stands up in court.
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