IMHO, this is key to the investigation.
This could possibly be on of the peices of evidence they want to hold back. We do not know if he had smoke in his lungs or evidence of whatever the smoke bomb stuff was in his bloodstream/tissues. (Not sure how it metabolizes.)
We do know the ccps took floorboards. Perhaps because someone (NOT a workman) entered the house and washed at the kitchen? What was going on at his house between the time he went to NYC and returned home? When did the noise from his house stop? Upon his return or before he returned?
Just a few rambling questions....
Sometimes, when people know they're going to be away from home for a few days leave their tv or lights on. Sometimes there's a timer, sometimes not.