"Semen was found on her body and has been sent for a DNA test," the autopsy panel chairman Police Colonel Pawat Prateepvisarut said yesterday.

He said the girl died of suffocation after a hard object was pressed against her throat. The autopsy also found injuries on her mouth, nose, bones and sexual organ.

Based on the autopsy results, Pawat believed the girl died on May 31, when she was last seen on the freighter, Prince of Tokyo, while it was docked in Sri Racha port in Chon Buri province.

"There was still rice and chilli that had yet to be digested in her stomach," he explained.

The Prince of Tokyo docked in Sri Racha on May 31.

The girl was on board with her mother, who had been employed to do temporary work on the ship while it was docked.

Police said the mother had lodged a complaint with the police after she was unable to find her daughter after work.

Seven days later, on June 7, the victim's body was found on board.

The freighter's captain alerted the employer of the victim's mother, said police spokesman Lt-General Ronnarong Yangyuen.

Her body was sent back to Thailand on Wednesday and sent for autopsy.

Lt-General Ek Angsananont of Provincial Police Region 1 said Sri Racha Police Station should have jurisdiction over the case because it was likely that the assault took place in the Sri Racha area.

"Investigators can check who was on the freighter that day," Ek said.

Lt-Colonel Supoj na Bangchang, who heads the police's office of legal affairs, said if the assault took place outside Thailand's territory, the Attorney-General could still pursue action against the attackers.