IAAI-CFI key terms

The room, compartment, or outdoor space where a fire began. Investigators first locate the general area, then narrow to a specific point of origin within it.

The precise location where the ignition source, fuel, and oxygen first interacted to start combustion. It is identified by fire patterns, witness accounts, and physical evidence.

The systematic process of analyzing fire patterns, damage, and witness statements to establish where a fire started. It precedes cause classification and must be supported by evidence.

The classification of a fire as accidental, natural, incendiary, or undetermined after identifying origin, ignition source, and the circumstances of ignition.

The heat energy component that initiates combustion, such as an open flame, electrical arc, hot surface, or friction spark. It must be capable of transferring enough energy to the fuel.

The ordered combination of fuel, oxygen, and heat source plus the circumstances that brought them together. Establishing this sequence is required before a cause can be classified.

A classification used when evidence is insufficient to assign a cause, or when competing hypotheses cannot be eliminated. It is a legitimate finding, not a failure of investigation.

Visible or measurable changes in materials caused by fire, including char, melting, oxidation, and smoke deposition. Investigators interpret them to trace fire spread and origin.

A triangular burn pattern on a vertical surface that widens upward from a point of origin. It indicates flame impingement and upward spread but does not by itself prove origin.

The measured thickness of charred material, sometimes used to estimate duration or intensity of heating. Interpretation requires caution because char rate varies with material and ventilation.

The dehydration and breakdown of gypsum wallboard when exposed to sustained heat, often leaving a grayish-white crumbly surface. It indicates heat exposure but not a specific temperature or time.

The transition when a compartment's contents and surfaces ignite nearly simultaneously due to accumulated heat. It dramatically changes fire behavior and can obscure the original origin.

A fire whose growth is limited by available oxygen rather than fuel. Such fires produce heavy smoke, incomplete combustion, and can create misleading patterns when ventilation changes.

The scientific method step in which candidate explanations for origin and cause are compared against evidence. Investigators must attempt to disprove each hypothesis rather than confirm a favorite.

Assigning a cause by eliminating all accidental sources without evidence proving an incendiary act. It is widely rejected because absence of evidence is not evidence of a cause.

The standard listing job performance requirements for fire investigators, including knowledge of fire science, building systems, and evidence handling. It also requires continuing education.

A statement in NFPA 1033 describing a task an investigator must be able to perform and the knowledge or skills needed to do it. These requirements define the exam's scope.

A disciplined approach of observation, hypothesis formation, testing, and conclusion used in fire investigation. Conclusions must follow from data and be revised when new evidence appears.

Evaluation of structural stability, utility hazards, and environmental risks before entering or working a fire scene. Investigators must document and mitigate hazards before evidence collection.

The systematic recording of a fire scene through notes, photographs, sketches, and measurements before disturbance. Complete documentation preserves origin and cause evidence for later analysis.

The documented chronological record of who collected, handled, and stored physical evidence. Gaps or breaks can undermine the admissibility and reliability of the evidence in legal proceedings.

Recovering, packaging, and labeling items such as debris, appliances, or ignitable liquid samples for laboratory analysis. Proper methods prevent contamination and preserve evidentiary value.

Traces of flammable or combustible liquids remaining in debris after a fire. Detection requires proper sampling, containment, and laboratory analysis such as gas chromatography.

A burn or staining pattern suggesting liquid fuel was poured or spread. It is not conclusive proof of an accelerant because melted plastics and other fuels can mimic it.

Any fuel or substance used to increase the rate or spread of fire. Its presence must be established by laboratory analysis, not by burn pattern appearance alone.

A heat source with sufficient energy and duration to ignite the fuel present. Investigators must show the proposed source could realistically have started the fire.

Examination of wiring, devices, and appliances to determine whether electrical energy initiated the fire. Investigators must distinguish cause from damage caused by the fire itself.

Recording locations of electrical arcing on conductors to help identify fire spread and possible origin. Arc sites indicate where wiring was damaged, not necessarily where the fire began.

The study of how fire grows, spreads, and interacts with its environment, including heat release, ventilation, and fuel arrangement. It underpins accurate pattern interpretation.

Categorizing structures by materials and systems, such as wood frame, masonry, or fire-resistive. Construction type affects fire spread, collapse risk, and pattern interpretation.

Structured questioning of occupants, responders, and bystanders to gather observations about fire conditions and events. Statements must be evaluated for reliability and corroborated with physical evidence.

A written summary of an investigator's findings, methodology, and conclusions prepared for legal or insurance purposes. It must disclose the basis for opinions and any limitations.

NFPA 1033 expects investigators to maintain current knowledge through ongoing training, such as at least 40 hours of fire investigation-related education annually.

The total amount and arrangement of combustible material in a space. It influences fire growth, duration, and the patterns that remain for investigators to interpret.

Accumulation of soot and combustion products on surfaces, which can indicate smoke movement and hot gas layers. Depth and location help reconstruct fire spread.

The area around a structure where falling walls or debris pose danger during and after a fire. Investigators must establish and respect it before entering the scene.