Zaid al-Hilli, whose brother Saad was mysteriously killed along with his wife and her mother in their car in September 2012, admitted to the BBC and the Sunday Times newspaper that the brothers were engaged in a bitter inheritance dispute -- but insisted he did not orchestrate the murders.
The 54-year-old, who was arrested in June on suspicion of masterminding the killings, also accused French police of failing to properly investigate the possibility that the real target was Sylvain Mollier, a Frenchman who was shot dead near the family's car as he cycled through the hills above Lake Annecy.
"They are covering up for someone in France in that region and they know it," Hilli, who is due to answer police bail on Wednesday, told the BBC.
"Mollier was involved in family disputes and was an outsider to (his) rich family. There is something more to it locally... most crime has local roots."
French investigators believe Mollier was an innocent bystander who was killed because he stumbled upon the murder scene.
Their lead theory is that a family inheritance dispute was the motive for the killings.
Zaid al-Hilli told the Sunday Times that the last time the brothers spoke, Saad had physically attacked him as they argued over the house in Claygate, a leafy suburb of London, which they had inherited from their mother.
"I was on the bed in my bedroom and he pinned me down," he said.
Zaid, who works as a payroll manager for a leisure company, said he had given 25 hours of interviews to British police but has refused to go to France for further questioning.
"The French, I don't trust them at all," he told the Times.
"My brother was killed there in that region and I am not going to take the risk."
He revealed that he had taken a day off work on the day of the murders, and gone to the English seaside resort of Worthing with a friend.
He also revealed that he has been taking anti-depressants since the killings and has buried himself in work to deal with his grief.
Zaid said the brothers, who were born to middle-class parents in Baghdad before the family moved to Britain in 1971, had enjoyed a close relationship but came to blows over the house.
He added that he did not think the motivation for the killings lay in the family's Iraqi connections. "That's all in the past," he told the Times.