Rory Bourgeois, 48, and George LeLoup killed in helicopter crash in the Gulf of Mexico on June 11.

It will take 12-18 months to determine the cause of the helicopter crash in the Gulf of Mexico Wednesday that killed a Thibodaux man and the pilot, federal investigators said. Rory Bourgeois, 48, of Thibodaux, was on the chopper as part of his job as an air-conditioning technician for BNA Marine Services. The victims were identified as Rory Bourgeois, 48, of Thibodaux, and pilot George LeLoup, whose hometown wasn’t released, National Transportation Safety Board officials said. The bodies of the victims were found Thursday by divers for Epic Divers & Marine of Belle Chasse and the Coast Guard, authorities said. They had been working aboard an oil industry support boat owned by Bahrain-based Adams Offshore Services. Investigators have determined the helicopter crashed off an oil rig landing platform about 60 miles south of Terrebonne Bay and sank into the Gulf, said Eric Weiss, a spokesman for the transportation agency. It was unclear where the helicopter had taken off, and the rig’s owner wasn’t identified. Bourgeois was flying in the Bell 206-L4 as part of his job as an air-conditioning technician for BNA Marine Services, an Amelia company that handles mechanical and repair needs for the marine industry.