WASHINGTON (AP) — Two U.S. officials killed in a vehicle crash as they returned from destroying a clandestine drug lab in northern Mexico over the weekend were working for the CIA, according to a U.S. official and two other people familiar with the matter. Two Mexican investigators also were killed in the crash, which Mexican authorities said occurred while the convoy was returning from an operation to destroy drug labs of criminal groups. There have been discrepancies in the public accounts of