It seems to me that that would be very difficult to determine in retrospect.

In any case, I think we can agree that militarized police breaching through a door and going in with guns drawn like they're going to assassinate Bin Laden all due to a phone call is dumb and shouldn't happen

They should send a drone to look into the window, or turn one of the dozen devices in each room into a microphone, or perform any kind of other investigation first before they do that.