According to fire investigation principles, what is critical to establish at the hypothesized origin?

Establishing a competent ignition source at the hypothesized origin is critical in fire investigation because it helps to confirm how the fire initiated. Identifying the ignition source allows investigators to connect the cause of the fire to the materials that were present, leading to a better understanding of how the fire spread and developed. This is crucial for determining whether the fire was accidental, intentional, or a result of negligence.

While the presence of witnesses, the history of the building, and the size of the fire can provide valuable context and support conclusions about the fire's circumstances, they do not directly establish the cause of the fire. A competent ignition source is fundamental to linking the fire's origin to the subsequent fire behavior and ultimately to the investigation's findings about responsibility and prevention.