Saif al-Islam, son of Libyan dictator Muammar Gaddafi, was killed during a "direct confrontation" with four unidentified gunmen who stormed his home, Saif al-Islam's office said, Reuters reported.
Although he held no official position, Saif al-Islam was considered the most powerful figure in the oil-rich North African country since his father Muammar Gaddafi, who ruled for more than four decades.
Saif al-Islam led negotiations for Libya to give up its weapons of mass destruction and negotiated compensation for the families of victims of the bombing of Panama Flight 103 over Lockerbie, Scotland, in 1988, Reuters reported.
Determined to rid Libya of its status as a pariah state, he engaged with the West and proclaimed himself a reformer, calling for a constitution and respect for human rights.
Educated at the London School of Economics and fluent in English language, he was once seen by many governments as the acceptable, Western-friendly face of Libya.
But when the uprising against Gaddafi’s long rule erupted in 2011, Saif al-Islam immediately chose loyalty to family and clan over his many friendships to become the architect of a brutal crackdown on the rebels he called rats.
In an interview with Reuters during the uprising, he said: "We are fighting here in Libya, and we will die here in Libya."
He warned that there would be rivers of blood and the government would fight to the last man, woman and bullet.
"The whole of Libya will be destroyed. "It will take us 40 years to reach an agreement on how to govern the country, because today everyone wants to be president or emir and everyone wants to govern the country," he said.
After rebels took the capital Tripoli, Saif al-Islam tried to flee to neighboring Niger, dressed as a Bedouin. Militia from the Abu Bakr Sadiq Brigade captured him on a desert road and took him by helicopter to the western city of Zintan about a month after his father was hunted down and executed by rebels.
"I am staying here. "They will fire all their weapons at me the moment I step outside," he said in a statement as hundreds of men crowded around an old Libyan air force transport plane.
Saif al-Islam was handed over to the rebels by a Libyan nomad.
He spent the next six years in prison in Zintan, far from the glamorous life he led under Gaddafi, when he had pet tigers, hunted falcons and mingled with British high society on trips to London.
In 2015, Saif al-Islam was sentenced to death by firing squad by a court in Tripoli for war crimes.
He was also wanted by the International Criminal Court in The Hague, which issued an arrest warrant for him for "murder and persecution".
Saif al-Islam Gaddafi spent years in illegality in Zintan to avoid assassination after being released by the militia in 2017 under an amnesty law. Since 2016, he has been allowed to communicate with people inside and outside Libya, said Mustafa Feturi, a Libyan analyst with contacts in Saif al-Islam's inner circle.
Saif al-Islam received visitors almost every week and discussed politics and the state of the country. He sometimes received gifts and books.
Dressed in traditional Libyan robes and a turban, he appeared in the southern city of Sabha in 2021 to file his candidacy for the presidential election.
He was expected to tap into nostalgia for the relative stability in Libya before the NATO-backed uprising in 2011 that ousted his father and ushered in years of chaos and violence.
His candidacy, however, was controversial and met with opposition from many of those who had "suffered at the hands of his father". Powerful armed groups, which emerged from the rebel factions that rose up in 2011, have rejected it outright.