Small propane heaters were utilized to provide heat. About an hour into the investigation there were complaints of being tired by several investigators. The cause was the build up of C0 in the warm and cozy building. The effects of C0 are cumulative and should not be taken hgyhtly. Fire fighters understand the term and practice on a regular basis regarding these spaces.
Common sense goes a long way in investigating a fire.
Remember that structurally the building is unsafe. Often in he Northeast the matter is complicated by ice conditions from fire department activity. Take that scenario one step further. In many rural areas you could be there for a while. You could be a candidate for Cryogenics without electing it.