International human rights groups called Friday for an investigation into the death of former Libyan leader Moammar Gaddafi as gory new videos showed him being spat at and punched by revolutionaries and as skepticism mounted about official claims that he was shot in crossfire after being captured.

The new cellphone videos cast a shadow over the revolutionaries even as they were celebrating the end of their eight-month struggle to wrest control of the country. NATO had backed the rebels in the name of shielding pro-democracy civilians from Gaddafi’s brutality.

“The government version certainly does not fit with the reality we have seen on the ground,” said Peter Bouckaert of Human Rights Watch, who has been investigating the capture of Gaddafi in his home town of Sirte. Amnesty International warned that the killing could be a war crime.

The firestorm over Gaddafi’s death occurred as NATO announced that its military mission would end Oct. 31.

“I’m very proud of what we have achieved, together with our partners,” Secretary General Anders Fogh Rasmussen said in Brussels.

But in Libya, a dead Gaddafi was proving almost as troublesome as a live one for the interim government.

Senior officials met into the night to consider the demands for an investigation and figure out how to bury Gaddafi secretly so that the grave would not become a pilgrimage site. His body was stored Friday in a refrigerated room normally used as a meat locker in Misurata, the home of the fighters who captured him, and local citizens were allowed to file by. Scores of people lined up for a glimpse of Gaddafi, whose troops partially destroyed the city in fierce fighting this past spring.

Snatches of cellphone video posted to YouTube and played on Arab-language television showed the revolutionaries trying to raise Gaddafi from the ground after his capture Thursday. His face was dripping with blood, his shirt splotched with crimson. But he was clearly alive.

“You dog! This is Misurata. Misurata captured you,” they taunted him. One spat in his face.

“Have pity! Don’t hit me!” Gaddafi cried.

Now you know pity!” one man responded.

Another video showed Gaddafi being punched and hit as he was splayed on a trunk hood.

State Department spokesman Mark Toner told reporters in Washington that the new Libyan government had “pledged to provide a full accounting of what happened, what transpired leading up to his death. And we look to them to do that.”

A U.N. official said a panel set up to investigate abuses in Libya would probably take up the matter of Gaddafi’s death.

“More details are needed to ascertain whether he was killed in some form of fighting or was executed after his capture,’’ said Rupert Colville, a spokesman for the U.N. Human Rights Council in Geneva.

Libyan Prime Minister Mahmoud Jibril had said Thursday that Gaddafi was uninjured when he was captured but was fatally shot in the head in “crossfire” between revolutionaries and loyalist forces as he was driven away in a truck. Bouckaert, of Human Rights Watch, said Friday that interviews with revolutionary commanders and loyalist fighters traveling with Gaddafi produced a very different account.

“Commanders I spoke to said chaos ensued” after Gaddafi was captured, with revolutionaries yanking his hair and abusing him, Bouckaert said. He said that Gaddafi had been shot in the leg and stomach before his capture but that he was “certainly not mortally wounded.’’

There were no reports in Sirte of firefights as Gaddafi was driven away, Bouckaert said.

“The rebels are not ashamed about it,” he said of the killing.

The Associated Press quoted a 21-year-old fighter who reported riding in the vehicle with Gaddafi out of Sirte as saying Gaddafi died en route to a field hospital of wounds he had already sustained. The fighter, Siraq al-Hamali, did not mention the vehicle coming under fire, the AP reported. A coroner listed Gaddafi’s cause of death as a bullet in the head and a chest wound.

“If Colonel Gaddafi was killed after he was captured, it would constitute a war crime and those responsible should be brought to justice,” Claudio Cordone, senior director at Amnesty International, said in a statement.

The group called for an independent investigation into the death.

While human rights groups said the death could throw into question the democratic credentials of the new Libya, people in the capital seemed unconcerned at the manner in which Gaddafi was killed. The issue did not come up in a sermon about the new Libya to hundreds of jubilant, flag-waving people who gathered for Friday prayers in Tripoli’s Martyr Square, formerly known as Green Square.

“He did worse” to the Libyan people, said Hisham Krekshi, deputy chairman of the Tripoli council of the interim government. “You think we care? It’s good he died.”

New videos also turned attention to how Gaddafi’s son Mutassim died Thursday. The video clip shows him seemingly lucid, sitting and smoking a cigarette as he is taunted by an off-screen revolutionary.

On Thursday night, the bodies of Gaddafi and his son had been moved between homes around Misurata every two hours, to avoid the crush of people who gathered outside, according to Tirana Hassan, a Human Rights Watch investigator in the city. On Friday, a long line of onlookers continued to seek to view the body, she said. Some yelled “God is great!” as they exited the meat locker, she said.

NATO’s decision to end its Libya operations will not be formally adopted until early next week. But Ivo Daalder, the U.S. ambassador to NATO, said member nations accepted the recommendation of military commanders that the mission could be rapidly dismantled. Commanders reported that the fall of Sirte was “a key indicator that the Transitional National Council has control over all major population centers.”

In reality, a NATO official said, maritime operations, the no-fly zone and most strike sorties have already ended, with countries removing their aircraft from NATO-controlled bases or keeping them grounded on an “on call” basis. The NATO airstrike that preceded Gaddafi’s capture was the first that had taken place in days, the official said.

Staff writer Karen DeYoung in Washington contributed to this report.