I got a call from the wife yesterday asking "Are these yours?" She then showed me a pair of 30" bolt cutters that she found hidden by the back door. She informed our police friend who took them to the lab for printing, but the police at the station were not really interested in the matter.
As i am currently of the country, my wife is trying to find somebody to make a few modifications to the back door because i am sure the owners will return. I am assuming, as the door is locked from the inside, that they will return with a crowbar to force the door or use a hacksaw to cut through the frame fixing bolts.