The fire itself is the first step in the collection and investigation of arson evidence. Experts have identified three factors that must be present in any arson case and these factors are known as the triangle of fire. These factors include oxygen, the source of fuel and the heat. In any case of arson, the oxygen concentration must exceed sixteen percent while the fuel can be any flammable material which include petrol, gas and other flammable materials. To this effect, the heat factor is considered to be any source of heat that can match the temperature of ignition of the fuel which will be aided by oxygen concentration. In an arson case, the arsonist must have tampered with one of the three factors that have been identified as the fundamental causes of a fire (NFPA 921, 2004).
An arsonist will make use of accelerants like alcohol, gasoline or kerosene to increase the fuel load to enhance higher chances of the fire developing. The arsonist may also increase the concentration of the oxygen and this can be achieved by various means like opening the windows of the structure that will ensure that the oxygen concentration will be higher in the structure. ...
e fire spreads from the top to the bottom, it is most likely that the fire will also spread in other rooms rather than be confined to one room of the structure (Bryant, 2008).
Arson fire is brought about by an individual introducing a heat source and the heat source can be as simple as the lighting of a match or can be as complicated as the introduction of very flammable chemicals which have been noted to be ignited even in very low temperatures. It is important to note that for a case to be considered as an arson case, the underlying statement is that the cause of the fire was deliberate. In such scenarios, it is therefore to right to say that an arson case have an individual who deliberately tampered with the three factors that are considered to be the cause of fire. These factors are the three triangles of fire (NFPA 921, 2004).
It is in this respect that an investigator who rules that the cause of fire was an act of arson must prove that the fire triangle was tampered with and that the other accidental causes of fire have been ruled out. This means that the investigator must have the knowledge that is required to differentiate between an accidental fire and a fire that was caused by an act of arson. It is in this respect that many fires that have been caused by acts of arson have been mistaken to be accidental fires and there is the requirement of well trained investigators to look into the fires that have been reported as accidental (Thomson Delmar Learning, 2004).
Analysis of flammable residue
In the analysis of the flammable residues the most instrumental method is the gas chromatograph. This is because it has been deemed by experts as the most sensitive and the most reliable method that can be used to detect and also in the characterization of the residues