A joint investigation is underway after a crewman from a north-east trawler fell overboard, sparking a massive rescue operation.
The fisherman disappeared off the Banff-registered Aquarius BF89 in the early hours of Monday morning.
Despite 11 vessels taking part in the search, the man was not found and hope faded when his empty life ring was recovered from the North Sea.
Now the Marine Accident Investigation Branch (MAIB) and the police have launched a joint inquiry into the circumstances of the incident.
The crew of the 68ft fishing boat put out a emergency distress call around 2am on Monday, reporting a man overboard close to Aberdeen’s Girdleness Lighthouse.
Skipper Scott Shepherd and his crew threw a life ring into the sea however search teams later recovered it from the water.
After eight hours and no sightings of the missing fisherman, the operation was called off at about 11.30am. The man has not been named.
Last night an MAIB spokeswoman said: “We are aware of the incident and we are investigating.”
A spokesman for the police in Aberdeen, who are assisting with inquiries, said: “We’ve been liaising on it. We’re making inquiries alongside the MAIB and the coastguard as well. This is a matter of routine.”
Last year the Aquarius was involved in an bizarre three-day chase with fishery inspectors around the north coast of Scotland
Mr Shepherd was fined £6,000 after ignoring repeated foghorn blasts from the patrol boat Jura and leading the government officials on a 120-mile chase.
The vessel had been fishing off the Butt of Lewis when inspectors tried to board and investigate her catch.
The crew, however, claimed they were oblivious to the whistles, and when the Aquarius was caught on the other side of the country, she was found to have a £53,000 catch of monkfish in her hold.
Stornoway Sheriff Court fined Shepherd for intentionally obstructing a sea fishery officer, a charge the skipper vehemently denied.
Mr Shepherd was unavailable for comment last night.