TURNER – A 56-year-old trucker who was killed Friday when his tractor-trailer truck went off Route 4 may have fallen asleep at the wheel.

M. Joseph Scott of Oxford was found dead at about 7:15 a.m. Friday. The accident is believed to have taken place nearly three hours earlier.

Stephen McCausland of the state Department of Public Safety said Scott was hauling paper products from Rumford to Auburn when his rig struck a signpost as it went off the road. Part of the signpost came through the windshield, striking the driver.

Part of Scott’s cargo shifted during the crash and ended up in the cab.

The accident remains under investigation.