A Marine Department investigation into the deaths of two labourers at the Yau Tong shipyard last month could lead to prosecutions for negligence. Safety measures were ignored on June 13 when four dockers entered a tank filled with poisonous gas. Two were killed. The Marine Department report was submitted to the Education and Manpower Branch and the Coroner's Court yesterday. A Marine Department source said: 'We have pointed out there could be some negligence on the part of the owner or the ship repair contractors.'