Abstract: At 7:00 a.m. on April 4, 2012 an employee was working at the Patterson-UTI Rig Number 235, just off County Road 192 in Gonzales County. The employee was guiding a walk board into place manually with both hands at a height of 50 feet on the oil rig derrick, Apex 1500. As the walk board was being hoisted into position, the employee was guiding it to ensure it did not get stuck or damage while being raised. The employee was going to secure the walk board into place once positioned. The employee had on a fall protection derrick harness with a double-leg lanyard attached to the dorsal D-ring and a double-legged lanyard system. One of the lanyard legs was loose and the other was hooked to the employee's right, front harness strap. The employee was changing position on the derrick when his feet slipped out from under him and he fell 50 feet on to the rig floor. The employee landed on the rig floor head first and bounced into a sitting position. One of the hooks from the double-legged lanyard was hooked to his front, right harness strap, while the other hook and lanyard was loose and not engaged. The derrick had excess crude oil or oil-based liquids visible on the beams of the derrick. Both legs of the lanyard system did not appear to have been engaged, and measured to be approximately six feet in total length. The immediate supervisor was on site and in plain sight of the work being conducted by the employee. The employee appeared to have landed on the upper right side of his head, and was killed from blunt force trauma.