Agreed - I would also think that the investigators would be familiar with the pattern on the bottom of a firefighter's boot. Maybe these guys fight so many fires that the details of any single fire become obscured in their memories. Still, I would at least ask the question.
WFTR
Bill
I can understand them not remembering now. But for goodness sake wouldn't the investigators have talked to them a day or two after the fire when they might have remembered something about it?