The man who the father of a Midland Lockerbie victim believes could hold crucial answers about the atrocity has been traced to a luxury resort in Qatar.
Musa Kusa is believed to have been an intelligence officer at the time of the 1988 Lockerbie bomb in which 270 people were killed.
He made a high-profile defection to Britain in March and was interviewed by police and Scottish prosecutors investigating the bombing.
He left the country following an EU decision to lift sanctions against him, meaning he no longer faces travel restrictions or an asset freeze.
Kusa was traced by the BBC’s Panorama programme, which is investigating allegations that he tortured political prisoners in Libya.
He declined to comment on the claims.
Kusa was head of Colonel Muammar Gaddafi’s intelligence agency from 1994 and a senior intelligence agent when PanAm flight 103 was blown up over Lockerbie.
The Boeing 747 jumbo jet was en route from London to New York when it exploded over the Dumfriesshire town, killing 243 passengers, 16 crew and 11 residents.
Libyan Abdelbaset Ali Mohmed Al Megrahi was jailed for mass murder in 2001 but was returned to Tripoli in 2009 on compassionate grounds after doctors treating him for prostate cancer gave him an estimated three months to live. He is still alive.
There have also been calls for Kusa to be quizzed in relation to the murder of Pc Yvonne Fletcher, who was shot during a protest outside London’s Libyan Embassy in 1984.
The Foreign Office said Kusa was a “private individual” who had been interviewed voluntarily.
Dr Jim Swire, from Worcestershire, whose 23-year-old daughter Flora died in the bombing, said that if anyone could offer any insight into the “huge questions still unanswered” on Libya’s role in Lockerbie, it would be Mr Kusa.
He said: “When I met Musa Kusa in Libya in 1991 it was clear to me he was the guy who was central to the Gaddafi administration.
“He could tell us just as much as Gaddafi about Lockerbie as he was at the core of the regime.
“He was a very, very key figure and we need answers as to why he was allowed to fly back and any probing over his crimes should be done by the International Criminal Court.”
Pamela Dix, who lost her 35-year-old brother Peter in the atrocity, said she was “incensed” at Mr Kusa being allowed to leave Britain in the first place.
She said: “We cannot turn a politically pragmatic blind eye.
“I do not know what Musa Kusa knows or does not know about Lockerbie but he needs to come back to answer those questions.
“I condemn the attitude of the UK Government in the strongest possible terms. A political hands-off attitude is inappropriate.”