Why be on the inside of the building??
There’s no windows… So where is the risk inside the building??
If there were three officers inside this one-story building - that maybe didn’t have an attic or ceiling separating the roof from the main room - wouldn’t they have heard someone crawling around on the roof? There’s an insulated crawl space between my one-level house and the roof, and I can hear crows when they are walking around on the roof.