When can a fire investigation be considered complete?

A fire investigation can be considered complete when the cause is determined to be an accident or act of nature because reaching a definitive conclusion about the cause provides clarity regarding the incident. This resolution indicates that all pertinent factors related to the fire's origin have been thoroughly examined and understood. It acknowledges that while the investigation has explored various possibilities, it has concluded with a clear understanding of the circumstances leading to the fire, allowing for proper documentation and potentially preventing similar incidents in the future.

Other choices present aspects of the investigation process, such as interviewing witnesses or examining for foul play, but these alone do not signify that the investigation is complete. An investigation focuses on establishing the cause, which is the primary goal that, when achieved, marks the investigation as finished, irrespective of other factors. Similarly, compromising the integrity of the scene might impact the investigation but does not define its completion.