A fire or explosion investigation is a complex endeavour involving skill, technology, knowledge, and science. The basic methodology of the fire investigation should rely on the use of a systematic approach and attention to all relevant details to first determine and establish the origin(s), then investigate the cause: circumstances, conditions, or agencies that brought the ignition source, fuel, and oxidant together.The determination of the origin of the fire involves the coordination of information derived from one or more of the following:

• Witness Information: - The analysis of observations reported by persons who witnessed the fire or were aware of conditions present at the time of the fire
• Fire Patterns: The analysis of effects and patterns left by the fire
• Arc Mapping: The analysis of the locations where electrical arcing has caused damage and the documentation of the involved electrical circuits
• Fire Dynamics: The analysis of the fire dynamics, that is, the physics and chemistry of fire initiation and growth and the interaction between the fire and the building’s systems

The propensity for different fire causation scenarios is evaluated based on the circumstances, the propensity for ignition due to either failure or action, and the correlation of the ignition scenario with the origin of the fire. Square Fire and arson experts examine the physical attributes of a fire scene and identify and collect physical evidence from the scene. These evidences are then analysed to help determine if the cause of the fire was accidental or deliberate (arson). During the scene examination, investigators may find evidence such as accelerants, tampered utilities, and specific burn patterns, which may indicate criminal activity