What kind of evidence can an eyewitness provide in the absence of physical evidence for establishing origin?

Eyewitnesses can play a crucial role in fire investigation, particularly when physical evidence is scarce or compromised. In such cases, reliable evidence of the early stages of a fire is valuable as it can help investigators understand how the fire began and developed before it became overwhelming. Eyewitnesses can recount specific details about what they observed in the initial moments of the fire, such as the presence of smoke, flames, or unusual occurrences. This information contributes significantly to reconstructing the circumstances surrounding the ignition and initial growth phases of the fire.

The other options, while they may contain elements of information that an eyewitness can provide, do not specifically focus on the key role of establishing the origin of the fire. The entire sequence of events may include too much information beyond the immediate origin. In-depth technical details would typically be outside the realm of an average eyewitness's knowledge and ability to provide, as these require specialized training. Lastly, witness accounts of fire suppression efforts can certainly be informative, but they do not directly address the origin of the fire itself, which is the primary focus of the question. Therefore, reliable evidence of the early stages is the most pertinent type of eyewitness testimony when establishing the origin of the fire in the absence of physical evidence.