Signs which may implicate another ship in the sinking of the Tullaghmurry Lass, in which three members of the same family drowned off Kilkeel, Co Down, are being examined by marine accident investigators.
The North's Agriculture and Fisheries Minister, Ms Bríd Rodgers, said a ship, which was docked in Warrenpoint the day the trawler vanished, has been examined by investigators but there was no evidence it was involved in the disappearance.
"I understand that the Marine Investigation Unit have taken scrapings of paint from all of the bumps on the ship, so that in the event of them finding the wreckage they will be able to either eliminate or confirm any involvement in its disappearance."
The retired admiral leading the investigation, Admiral John Lang, confirmed that a vessel which docked at Warrenpoint after the boat went missing had come under suspicion.
Meanwhile, a second British navy ship is expected to join the search for the Tullaghmurry Lass.
Mr Michael Greene (54), his 32-year-old son and eight-year-old grandson, also called Michael, never returned from a fishing expedition from Kilkeel a fortnight ago. The Irish Naval vessel, the LE Eithne, is also searching.