Shukri Ghanem, a former Libyan premier and oil minister who abandoned Muammar Gaddafi's regime to support the rebels, has been found dead in a section of the Danube river flowing through Vienna, Austria.
Police spokesman Roman Hahslinger said the his body was found floating in the river yesterday morning. It showed no external signs of violence, but the cause of death was not immediately clear and an autopsy will be carried out.
"There would be no signs of violence if someone pushed him in," Mr Hahslinger said. "But it's also possible that he became ill and fell into the water."
An Austrian foreign ministry official said family members initially told the ministry that Mr Ghanem, 69, had died of a heart attack, adding that their version appeared to be plausible.
Mr Ghanem was dressed normally when found in the river but had no personal identification other than a document that named the company he was working for, Mr Hahslinger said. An employee of the company was subsequently contacted and identified him.
Mr Hahslinger said Mr Ghanem apparently left his Vienna home in the early morning after spending Saturday evening at home with an acquaintance.
Police were alerted by a passer-by who saw his body floating near his home, close to the modernistic building housing United Nations agencies in the Austrian capital.
Mr Ghanem was a former Libyan premier who last served as his country's oil minister until last year. He left Libya for Tunisia and then Europe in June as insurgents were pushing to topple Gaddafi, and he subsequently announced he would support the rebels.
He was said to be autocratic at home but reporters covering the Organisation of the Petroleum Exporting Countries remembered him as a friendly man who readily gave his mobile phone number to selected journalists covering OPEC ministerial meetings and gracefully took even late-evening calls.
With advanced degrees in law and economics, Mr Ghanem served in senior positions within the Vienna-based OPEC before his appointment as Libyan prime minister in June 2003 - an office he held until 2006 when he took the oil ministry portfolio.
Considered a member of Gaddafi's inner circle until his defection, he insisted that Libya bore no responsibility for the 1988 bombing of Pan Am Flight 103 over Lockerbie, Scotland, which killed 270 people.
He also repudiated Libyan responsibility in the 1984 shooting death of WPC Yvonne Fletcher during a protest in front of his country's embassy - an incident that led to the severing of British-Libyan relations.
Such comments branded him as a loyal servant of the Gaddafi clan. At the same time, he worked quietly from the inside to change the face of Libya.
He became premier as the country began to transform itself from an international pariah accused of fomenting terrorism and crippled by sanctions to one seen as instituting reforms that led to growing economic and political ties with the United States and Europe. That process was bolstered by Gaddafi's decision to give up Libya's fledgling nuclear arms programme in 2003.
Mr Ghanem's efforts were supported by Saif al-Islam, the Gaddafi son associated with the reform wing. At the same time, he was viewed with suspicion by the old guard opposed to change - and their opposition to him led to his ousting as prime minister and subsequent appointment as head of the state oil company and de-facto oil minister.
He was reinstated in those positions in 2009 just weeks after his resignation, a move reflecting the power struggle between reformists and nationalists in his oil-rich North African nation.
Mr Ghanem continued to live in Vienna after Gaddafi was ousted and later killed last year in the Nato-backed rebel campaign.