A terrorist mastermind from Libya who was dubbed "The Professor" because of his criminal expertise is being sought by authorities in the bombing of Pan Am Flight 103, a London newspaper reported Sunday. Investigators have said Flight 103 was destroyed by plastic explosives hidden inside a radio-cassette player. The Boeing 747 blew up over Lockerbie, Scotland, on Dec. 21, killing 270 people. The Sunday Express, quoting unidentified West German detectives, said authorities believe the bombing was plotted by a Libyan nicknamed "The Professor" because of his electronics and explosives abilities.