Libyan rebels appeared to have "summarily executed" Gaddafi loyalists when they overran the dictator's hometown last year, said Human Rights Watch.
The report by the rights group, released Wednesday, claimed that some of the rebels in the militias that fought to oust Muammar Gaddafi committed war crimes, according to the Associated Press.
Titled "Death of a Dictator: Bloody Vengeance in Sirte," the report details the last hours of Gaddafi's life on Oct. 20, 2011. Gaddafi's convoy was struck as he tried to escape the besieged city, and militias attacked the survivors.
The press release from HRW said the report "presents evidence that Misrata-based militias captured and disarmed members of the Gaddafi convoy and, after bringing them under their total control, subjected them to brutal beatings."
"The evidence suggests that opposition militias summarily executed at least 66 captured members of Gaddafi’s convoy in Sirte," said Peter Bouckaert, the emergencies director at HRW. "It also looks as if they took Muatassim Gaddafi, who had been wounded, to Misrata and killed him there. Our findings call into question the assertion by Libyan authorities that Muammar Gaddafi was killed in crossfire, and not after his capture."
More on GlobalPost: The death of Gaddafi: The fall of a dictator
HRW said the most compelling piece of evidence comes from a cell phone video, showing the captured convoy members. "In case after case we investigated, the individuals had been videotaped alive by the opposition fighters who held them, and then found dead hours later," said Bouckaert, according to NBC News.
GlobalPost reported last year on the possible commission of war crimes and abuses, including the execution of dozens of pro-Gaddafi prisoners, by rebels. GlobalPost correspondents also provided detailed accounts of evidence that Gaddafi was executed.
The official account of Gaddafi's death given by the Libyan authorities reports that he and his son Muatassim died in crossfire.
"Video footage shows that Muammar Gaddafi was captured alive but bleeding heavily from a head wound," said the report. But footage showed that he was "severely beaten by opposition forces, stabbed with bayonet in his buttocks, causing more injuries, and bleeding. By the time he is filmed being loaded into an ambulance half-naked, he appears lifeless," according to the AP.
A video obtained by GlobalPost last year seems to corroborate this evidence, showing the former leader dragged from a drainpipe in which he was hiding and being sodomized.
Bouckaert said the Libyan authorities' refusal to investigate the atrocities committed by former rebels shows a "government in denial."
"They are not in a position to confront the militia," he said, according to NBC News. "It shows who's in power in Libya."
Following the attack on the US consulate in Benghazi by a militia last month, Libyans staged mass protests against the powerful militias and the government began a crackdown, issuing an ultimatum for the militias to either fall in line with the government or disband.
More on GlobalPost: Was Muammar Gaddafi executed? (VIDEO)
WARNING: Extremely graphic
Full video of Gaddafi's capture: