The brothers of a man who disappeared from a North Sea ferry 40 years ago said they always suspected it to be a foul play or murder case.
Kevin Dundon, from Essex, was aged 22 when he went missing while on a vessel returning to Felixstowe from Zeebrugge in Belgium, on 21 September 1980.
Suffolk Police is reviewing the case and said there was "growing support" his disappearance was not accidental.
Tom Dundon said he was told at the time "bad things happened on the boat".
Kevin was one of five children from an Irish family who lived in Clacton-on-Sea.
He had been close to his three brothers Jimmy, Tom and Danny, and their sister Jennifer.
Kevin had stayed with his brother Tom in Ipswich the night before he went to work on the Viking Viscount.
Tom, who was 23 at the time, said he never expected not to see his brother again when he dropped him off at Felixstowe ahead of that fateful trip.
"It didn't seem real," he said. "We were all in shock, in disbelief."
Kevin was employed by shipping company Townsend Thoresen and had been working on the vessel for three days when he disappeared.
His duties included washing crockery in the galley.
Witness statements from colleagues said he was working in the plate room at about 18:00 BST that Sunday, and the last confirmed sighting of him was 30 minutes later when he was believed to have been seen exiting the galley through a door which could have taken him to either the toilets or the deck.
"When he wasn't working, all of them would nip into the ship's bar for a drink," said Tom.
"There were lots of crew and a few passengers in that ship's bar and they were having drinks and laughs.
"Kevin was going back to work and then coming back in again and having a drink maybe and going back to work and then suddenly he went missing.
"Whilst now we have more detailed information and the police have more detailed information, we are looking for the final piece of the jigsaw."
Tom said he received a phone call in the early hours of the Monday from a priest at Felixstowe who told him that immediately after the ship had docked, a crew member went to talk to him about what happened on the boat.
"The padre said to me that he couldn't tell me what he said but don't let it drop, bad things had happened on the boat," said Tom.
In the early days of the investigation, the three brothers said they felt frustrated as police were leading the family to believe it was a missing person's inquiry.
But for Jimmy, Tom and Danny, they never believed their brother - who they described as "enjoying life" - would just disappear.
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"He was not that type of person and none of us thought he was missing, we all thought something bad had happened and we weren't going to see him again," said Danny.
Their mum Rita also told the press at the time: "There's no way he would've taken his life or disappeared."
Jimmy, Tom and Danny, now aged 65, 63 and 60 respectively, remember Kevin as being "chilled out" with a great sense of humour and someone who would make friends easily.
They said he loved music, buying clothes and taking lots of photos with his Polaroid camera. He would go out for a drink with them and was dating a local Clacton girl at the time, they said.
Their mum and dad Paddy "fell to pieces" after his disappearance and both they and Jennifer died without knowing what really happened.
The trio described the early investigation as a "calamity of errors".
However, they said Suffolk Police had done a "tremendous job" over the last two years when it was picked up by the cold case review team.
'We want closure'
They said their DNA had been taken and police had re-interviewed "just about everybody" and interviewed some people who may not have been seen the first time around.
Tom said: "We are 100% certain that there's at least one person, maybe one family, who knows what happened and we would appeal to them to help our family to have some closure on it."
"Kev was mine and Jimmy's little brother and one of Danny's older brothers. We've never been able to have a funeral. We've never been able to actually put it to bed. We want closure for our brother."
Suffolk Police continues to appeal for fresh information.