(CNN) - The crew of the drill rig Deepwater Horizon may have been overworked and short of key personnel before the explosion that unleashed the worst oil spill in U.S. history, a leading Democratic congressman suggested Tuesday.
Payroll records show that seven of the 11 men who died on the rig had worked a 24-hour shift six days before the explosion, Rep. Nick Rahall wrote in a letter to rig owner Transocean Ltd. Records from the rig showed "zero engineers, electricians, mechanics or subsea supervisors" on duty the night of the April 20 explosion, he wrote.
Rahall, D-West Virginia, the chairman of the House Natural Resources Committee, called on Transocean to give the committee more detailed logs and a further explanation of its staffing. There was no immediate response from the company to the letter.
Transocean, well owner BP and oilfield services contractor Halliburton have blamed each other for the disaster that followed the explosion. The undersea well the rig was drilling has been gushing up to 19,000 barrels (798,000 gallons) of crude a day into the Gulf of Mexico since late April.