Delta Flight 139, a TriStar with 211 passengers and 11 crew, was taxiing towards the terminal at Dallas Ft.-Worth International Airport when a male passenger ran to the forward cabin area from the back of the aircraft, grabbed a male flight attendant, and placed a pocket-knife with a 3-inch blade to his throat. The passenger had boarded the aircraft at Ft. Lauderdale, Florida, after going through normal preboard screening. The man stated that he was hijacking the aircraft and demanded access to the cockpit. He also claimed to have a hand grenade. During the first hours of negotiations, he allowed all the passengers to deplane and demanded that he be provided police protection for himself and his family from what he described as “Mafia hit men.” He never said where he wanted the aircraft to go. After about two hours of negotiations, the flight-attendant being held by the hijacker managed to escape from his grasp and he was overpowered by FBI agents. No grenade or explosive device was found. He was arrested and charged with air piracy and interference with a flight crewmember but was subsequently found not guilty by reason of insanity. There were no injuries during the hijacking.