Abstract: An accident occurred on 01/30/06 at about 08:15 A.M., at 170 King Street, in San Francisco. It was reported to the Division by the SF-Fire Department and employer on the same day. The Division responded to the accident on 02/06/06 at about 2:00 P.M. The injured (employee #1) was working on the construction of the 10th floor elevator core on the South Tower. He began stripping the elevator core wall forms with two other employees (employee #2 Carpenter Foreman and #3 Carpenter). They were removing pour platforms, wall braces and other equipment to prepare the form panels to be taken away by the crane. The procedure called for one last tie (taper tie, or wall tie) to stay in place to secure the panel until the crane supports, and to only remove it at that time. In this case, unbeknownst to anybody, the tie had been removed by an unidentified party, so, as employee #2 was removing the rest of the equipment, the 12'H x 14'W steel wall panel began to fall behind him. Witnesses yelled out to the injured to watch out. He then ran to get out of the way of the panel which still struck him on the lower back and pushed him forward hitting his head on a unit of 4"x 6" lumber. SF-Fire Dept. and ambulance personnel arrived on scene and began treating the injured. He was rushed to San Francisco General Hospital. Conclusion: The investigation was completed on 04/04/06. It has been determined that the serious injury was caused by the violation of California Code of Regulations Section 1713(b) Framing and Concrete Forms. The Division's investigation did not identify who and when had removed that last taper tie. Therefore, it cannot disprove employer's contention that employer could not have detected this condition, exercising reasonable diligence. As a result, the cited violation could not be classified as Serious Accident-Related, but General.