Human Rights Watch alleged today that Libyan rebels "summarily executed" scores of fighters loyal to Muammar Gadaffi, and probably the president himself, when they overran his hometown a year ago.
A report by the US-based group on rebel abuses following the October 2011 capture of Sirte is one of the most detailed descriptions of war crimes committed by the militias that toppled the ex-leader.
The 50-page report Death of a Dictator: Bloody Vengeance in Sirte, details Gadaffi's fate when he tried to flee the besieged city.
His convoy was struck by Nato aircraft as it fled and the survivors were attacked by militias who captured and disarmed them.
"The evidence suggests that opposition militias summarily executed at least 66 captured members of Gaddafi's convoy," said spokesman Peter Bouckaert.
HRW found a video clip showing prisoners from Gaddafi's convoy being abused by rebels.
The remains of least 17 were later identified in a group of 50 bodies, some still with their hands tied behind their backs.
Mr Bouckaert said the group's "findings call into question the assertion by Libyan authorities that Gaddafi was killed in crossfire and not after his capture."
But Suleiman al-Fortia, a member of the dissolved National Transitional Council, still insisted that "all the killings took place in a crossfire."
But HRW said that, "under the laws of war, the killing of captured combatants is a war crime and Libyan civilian and military authorities have an obligation to investigate violations of international humanitarian law."