A man in Turkey has been questioned in connection with the murder of kidnapped Briton Ken Bigley in Iraq in 2004.
Ken Bigley was killed by Iraqi militants
Loa'i al-Saqa, a Syrian national, is in custody in Turkey standing trial for the bombings of the British consulate and other buildings in 2003.
He was questioned by a local prosecutor in the presence of British police, BBC correspondent Sarah Rainsford said.
Mr Bigley's brother Stan, from Wigan, hoped it would lead to Mr Bigley's missing body being recovered.
The engineer from Liverpool was kidnapped in Iraq more than two years ago and later beheaded by his captors. His body has never been found.
Wave of attacks
Last April, a lawyer acting for Mr al-Saqa said his client had information on the execution, claiming he had taken part in the mock trial of Mr Bigley and knew where his body was buried, close to the city of Fallujah, our correspondent said.
Metropolitan Police officers are now investigating and trying to investigate Mr al-Saqa's claims.
Mr al-Saqa was interviewed for one-and-a-half hours in the city of Kocaeli, according to Turkey's Anatolia news agency.
The Syrian is currently on trial for a wave of suicide attacks in Turkey in 2003 which targeted the British consulate, a British-owned bank and a synagogue and killed dozens of people.
His execution was taped by his captors
He denies the charges and has refused to co-operate with the secular court, saying he does not recognise its authority.
Mr Bigley's brother Stan said: "We were told by the authorities that this was happening and we are hopeful. I can't put it any stronger than that.
"We are not banking on anything coming out of this but we can only hope that this could help us find Ken's body.
"We all hope they do find him, especially for my mother's sake."