Abiodun David John, 33, is said to have tried to access money belonging to Saad Al-Hilli, 50, who was shot dead close to Lake Annecy, in eastern France, on September 5. The wife and mother-in-law of Mr Al-Hilli, of Claygate, Surrey, died alongside side him, while a French cyclist was gunned down nearby.
Now it is claimed that John tried to access Mr Al-Hilli's Royal Bank of Scotland and HSBC accounts within a few days of the quadruple murders. John's arrest by Greater Manchester Police in Salford followed a request by Annecy magistrates and Surrey Police, who are leading the hunt for the killer.
A raid on his flat yielded numerous mobile phones and documents, said an investigating source.
John, in turn, insists he is innocent, and told the Manchester Evening News: 'I believe that people have been tapping into my phone and accessing my internet.
'When the police came into my house I did not know what they were talking about. They were talking about a dead man and said that I did it - took some money from a dead man's account.
Police search the Annecy scene of the murders of Saad Al-Hilli, his wife Ikbal, mother-in-law Suhalia and a cyclist
The quadruple murder took place in the forest near Chevaline and Lake Annecy in the French Alps
'Somehow they connected this to me. I do not know where this has come from.
'They took me to the police station and they explained why I had been arrested.
'I was completely shocked. I did not know where the police were coming from. I am totally innocent.
'I do not know where this whole thing has come from.'
A Greater Manchester Police spokesman said: 'A 33-year-old man was arrested..on suspicion of fraud offences and taken to a police station where he was questioned and released on police bail. The arrest was made on behalf of Surrey Police.'
John is due to answer bail at Guildford police station in Surrey on Tuesday.
More than 150 officers are involved in the Anglo-French operation to try and find the Annecy killer, but so far there have been no arrests. Detectives have been baffled as to why Mr Al-Hilli, his wife Ikbal, 47, and mother-in-law Suhalia, 74, were shot dead.
A variety of theories have emerged regarding the motive for the killings.
Media reports have linked Mr Al-Hilli with a secret trust account thought to include £15million in illegal kickbacks to Saddam Hussain's regime. But French police last month denied any link between the British engineer and Saddam Hussain.
The idea that the killer may have been a lone psychopath was 'gaining ground' according to police. Officers suggested that the type of gun the killer used - a 7.65mm Luger - is not consistent with the work of a trained assassin.
It has also been suggested that the cyclist killed may have been the main target and that the family were simply in the wrong place at the wrong time.
Annecy prosecutor Eric Millaud admitted last month that there was no 'immediate prospect' of the crime being solved and that the investigation would be a long process.
Source: UK Mail