Spat at in public by a fellow Libyan who called him a thief, watching his back on long walks through Vienna, eating poorly; Muammar Gaddafi’s fugitive oil supremo was a troubled man in the months before he was found drowned in the Danube two weeks ago. Just whom, or what, Shokri Ghanem feared may hold a key to his mysterious sudden death, just as he was under mounting pressure to reveal what he knew of suspect deals with foreign oil buyers that made billionaires of the late dictator’s family.Ghanem, a former prime minister who ran Libya’s oil industry until he fled during last year’s civil war, was in negotiations when he died with the victorious former rebels to give evidence, a source close to those discussions in Tripoli told Reuters.But Ghanem himself told Reuters in December, two months after Gaddafi was killed and shortly after his son Saif al-Islam was arrested, that he feared returning to Tripoli: "One man they were interviewing, they threw him out of the window,” he said.Sitting in a Vienna hotel lobby, one eye on the door, fidgeting with his mobile phones and showing little of the easy charm and wit that made him many friends, he added: "If you’re successful, there’s always someone who wants to try to get you.”Libyan Prosecutor General Abdelaziz al-Hasadi told Reuters on May 2 that he had a warrant for Ghanem to be "brought in”. But the oilman was regarded as a witness not a suspect, at least for the time being, would not necessarily be imprisoned and, Hasadi said, the warrant did not have force internationally.As the holder of a European passport, Ghanem need also have had little fear of a rapid extradition to a country lacking a stable legal system - among his grateful energy clients, Silvio Berlusconi’s government granted him Italian citizenship under a presidential decree published in December 2008.The Libyan government, struggling still to impose order on a country where rival militias hold great sway, has said little of the case beyond expressing surprise and noting, however, that Austrian police had found no evidence yet of any crime.