Libya's National Transitional Council has delayed the burial for Muammar Gaddafi in order to arrange a secret location and allow for an investigation into his death, officials say. On Friday, as videos continued to surface showing the fugitive deposed leader being captured alive by a crowd of NTC fighters, the United Nations' human rights office called for an investigation into how he died. "Taken together, they were very disturbing," Rupert Colville, spokesman for the office of the UN High Commissioner for Human Rights, said of the images. Gaddafi's body is being kept in a cold storage site in Misrata, where it was taken after NTC fighters captured and killed him in his hometown Sirte on Thursday. It bears a bullet hole in the head, the Reuters news agency reported. Mohamed Sayeh, a senior member of the NTC, told the Associated Press news agency that a "third party will come from outside of Libya to go through the paperwork" relating to Gaddafi's death. Sayeh said Gaddafi would be given a private burial with respect and in accordance with Islamic principles. Following Gaddafi's death and the pending declaration of "liberation", which the NTC had pegged to the fall of Sirte, NATO nations were also expected to decide on Friday to phase out their seven-month air and sea mission, which played a crucial role in defeating Gaddafi's armed forces, alliance officials and diplomats said. Captured alive In the hours following Gaddafi's capture, NTC officials and fighters gave differing accounts of what happened, but several videos taken by fighters at the scene showed him being taken alive, though bleeding from the left side of his head. In the videos, fighters shout, scream and fire their weapons in the air. Some can be seen punching Gaddafi and pulling his head down by his hair. Gaddafi, appearing dazed, gestures to them and touches his wound, then displays his bloody hand. No videos have emerged showing the moment of Gaddafi's death, and it is unclear exactly how he received his mortal wound. The first video, received by Al Jazeera, showed his lifeless body lying on the pavement. An international commission of inquiry launched by the UN Human Rights Council is already investigating killings, torture and other crimes in Libya, and Colville, the UN human rights office spokesman, said he expected that panel would look into Gaddafi's death. "It is a fundamental principle of international law that people accused of serious crimes should if possible be tried," he said. "Summary executions are strictly illegal. It is different if someone is killed in combat." Jibril claims 'crossfire' According to some reports from Sirte, Gaddafi and an escort of bodyguards had attempted to break out of the siege of the city, which had lasted for more than a month. Their convoy was struck by French fighter jets and a US Predator drone, and a wounded Gaddafi took cover in a drainage pipe with his surviving entourage. Pursuing NTC fighters fired at the group as they fled, then fought and killed some of the men guarding Gaddafi and took him captive, Reuters said, quoting eyewitnesses. Mahmoud Jibril, the NTC's de facto prime minister, initially said Gaddafi had been killed in a "crossfire" and that it didn't matter what happened to Gaddafi's body "as long as he disappears". Jibril pledged to resign after the fall of Sirte, which the NTC set as the final criterion for declaring the "liberation" of Libya. "He was alive up to the last moment, until he arrived at hospital," in the city of Misrata, Jibril said. Abu Bakr Younus, Gaddafi's defence minister, and Mutassim, one of Gaddafi's sons and former national security advisor, were also killed in Sirte on Thursday. NATO mission to end A decision to gradually wind down the mission was expected to be taken at a meeting of ambassadors of the 28 NATO nations in Brussels starting at 1430 GMT, based on recommendations from NATO military commanders. "Certainly surveillance will continue as we need to continue to monitor the situation," one official said. NATO officials said the decision would take into account the ability of Libya's interim authorities to maintain security. On Wednesday, NATO ambassadors put off a decision because of caution by countries such as Britain and France, which have been at the forefront of the military intervention. "Clearly the operation is coming to its end," French President Nicolas Sarkozy said on Friday. William Hague, the British foreign minister, said on Thursday that Gaddafi's death brought the end of the operation "much closer", but added: "I think we will want to be sure there are no other pockets of pro-Gaddafi forces still able to threaten the civilian population."