Post-mortem tests on three men who died in an accident on a gas rig support ship in the North Sea have failed to determine the cause of their deaths.
The Viking Islay is an emergency response and rescue vessel
Finlay MacFadyen, Robert O'Brien and Robert Ebertowski were securing an anchor chain when the accident occurred off the East Yorkshire coast on Sunday.
Police are now waiting for the results of toxicology tests.
Detectives are speaking to the men's crewmates to build a clearer picture of the events leading up to the accident.
Mr MacFadyen, 46, from Aberdeen, Mr O'Brien, 59, from Leven in Fife, and Mr Ebertowski, 40, from Gdynia, Poland, were taken to Hull Royal Infirmary by a Sea King helicopter after the accident but died from their injuries.
Humberside Police said a team of detectives were talking to the remaining nine members of the crew, who had been on board the Viking Islay for just a day when the accident happened.
They were expected to work out at sea for 28 days.
A spokeswoman said the men's families were going to meet with senior investigating officer Det Ch Insp Tony Garton about the case.
The Viking Islay is currently berthed at Immingham, North East Lincolnshire, where a full investigation is being carried out by the Marine Accident Investigation Branch.
The ship, an emergency response and rescue vessel, was supporting the Ensco 92 drilling rig on BP's Amethyst field when the accident happened.