inside airport is considered federal property. It depends on arrangement with the local law enforcement authority. Is the police under city authority or port authority or something else. Usually passenger area is under the local jurisdiction. Inside TSA area and outside there inside and outside the airport. Federal agency usually has authority on the tarmac in inside secure areas like baggage claimtrackarea.. unless this is a hub airport where you have more airline baggage employees and their transfer system, the baggage claim is not the airline area but under the airport authority/ feds

The airline is responsible. Did the Arline do an arrival scan before putting it on the claim track.