Two convicted killers have been named by police as prime suspects in an unsolved murder case dating back more than 20 years.
Kenneth Regan and William Horncy are believed to be responsible for the death of 53-year-old Michael Schallamach, from Southampton, who disappeared in April 1992.
They are currently serving whole life sentences for the murder of the Chohan family in 2003.
A Hampshire Police spokesman said: "Armajit Chohan was murdered by Regan and Horncy to steal his freight business so they could use it as a front for drug running.
"They also murdered Armarjit's 25-year-old wife Nancy and their two young sons, 18-month-old Devinder and two-month-old Ravinder along with Nancy's 51-year-old mother Charanjit Kaur.
"Hampshire Constabulary's Major Investigation Team now believe that Regan and Horncy murdered Michael Schallamach 10 years before."
The spokesman went on: "At the time of Mr Schallamach's disappearance the police and his family were told by his associates that he had run away with another woman to live in Europe or Nigeria.
"His wife Yvonne even received a handwritten letter sent from France from a person, allegedly called Helen, stating they had run off together."
Officers will be appearing on the BBC's Crimewatch Roadshow on Thursday in a bid to identify the letter writer and appeal for information about Mr Schallamach's disappearance.
The letter sent to Mr Schallamach's wife
Detective Chief Superintendent Ben Snuggs said: "Mr Schallamach's family have spent almost a quarter of a century not knowing what happened to him and I'm appealing for the public to help us finally solve this long-running murder inquiry."
The Old Bailey trial heard that the Chohan family disappeared from their Hounslow home in February 2003.
Regan, a convicted drug dealer who was a police informant, planned to take over Mr Chohan's successful CIBA freight company to use it for importing drugs.
He lured him to Stonehenge, Wiltshire, and forced him to sign over his company before murdering him.
The rest of the family had been killed and buried at a farm in Tiverton, Devon and the bodies later taken out to sea and dumped.
The bodies of Mr Chohan and his wife were found in the water off Bournemouth, while Mrs Kaur was found off the Isle of Wight.