Ian Spiro, 46 - who was found dead in his car in the Californian desert in November 1992 days after his wife and three children were killed in their San Diego home - was said to have been a "low-level conduit" for the CIA. He was said to have been recruited by the disgraced United States Marine Lieutenant Colonel Oliver North because of his extensive business contacts in the Lebanon.
But the hearing at Whitehaven magistrates' court was also told that San Diego police concluded Mr Spiro had committed suicide after killing his family because of pounds 3.5m business debts.
The West Cumbria coroner recorded a verdict of unlawful killing on Mr Spiro's wife, Gail, 42, and their children Sara, 16, Adam, 14, and Dina, 10, who were shot while in their beds at the family's home at Rancho Santa Fe in November 1992.
Mr Spiro, who was found dead from cyanide poisoning in his car in the Californian desert days later, on 8 November, was not subject to the proceedings in Whitehaven because he had been cremated and buried in the United States.
In a statement read out by the coroner, John Taylor, Mrs Spiro's mother, Margery Brunskill, said that her son-in-law had been employed by the CIA and British intelligence. "We believe that Ian was murdered by some terrorist group originating from the Middle East or under the direction of the CIA," she said. Mr Taylor added that the family was unhappy with the US police's version of events and would be continuing their fight to get the full facts disclosed.
A book by a US expert on terrorism has claimed that Mr Spiro - who had often been called James Bond because of his accent and "activities" - had been "liquidated" by an Iranian hit squad for being prepared to reveal the identities of those behind the hostage-taking in Lebanon.
In a statement read out at the inquest, Eugene Douglas, former US ambassador to Britain, said that he knew Ian Spiro to be a CIA agent who used the name John Smith.
Interviewed by Federal Bureau of Investigation officials, Mr Douglas had said in the statement:"Spiro had a part in the release of Terry Waite and had passports in several names and from several countries.
"He had 15 to 20 years working in Beirut and had strong links with the Shias, that is how he was brought to the attention of the CIA and to Oliver North."
Mr Douglas referred to the dead man as "not a covert employee" of the CIA but a "low-level conduit." Before his death Mr Spiro had contacted Mr Douglas wanting help from Robert Gates, head of the CIA - but the message was never passed on.
A 1995 San Diego police department report found that Mr and Mrs Spiro owed $5m to various banks, credit cards and individuals. They examined evidence that Mr Spiro had tried to use a Ouija board to help him win the California lottery and a book called Final Exit, on the best methods of suicide, which was found in his car. The report concluded: "It is evident that Ian Spiro killed his family and then committed suicide. Case closed. Suspect deceased."
After Ian Spiro was found dead, backpackers discovered belongings of his in the desert, including tapes recorded on a dictaphone. A US clinical psychologist concluded that he had become an "isolated and rigid" individual whose "melancholy attitude "had taken him beyond depression".
Mr Taylor said: "The family do not accept the circumstances of the report by the San Diego Police and I understand they are involved in further investigations in America.
"This was a tragic case," he added.