(CNN) -- The United Nations called for an investigation into the death of Moammar Gadhafi as questions lingered over the last moments of the late Liyban strongman's life.
Meanwhile, NATO officials were expected to huddles in Brussels as the alliance considered its next moves in the war-ravaged nation.
Both the Office of the U.N. High Commissioner for Human Rights and Amnesty International want the circumstances around Gadhafi's death to be probed. "More details are needed to ascertain whether he was killed in the fighting or after his capture," the U.N. agency said.
"There seem to be four or five different versions of how he died. As you are aware, there are at least two cell-phone videos, one showing him alive and one showing him dead. Taken together, these videos are very disturbing."
CNN released animation of how Gadhafi was likely captured. It showed a compound with people shooting guns, then a truck convoy over the pipes where Gadhafi was found as planes come and bomb the convoy over the drainage pipes.
Amnesty International urged Libya's interim leadership, the National Transitional Council, "to make public" all the facts of Gadhafi's death.
"It is essential to conduct a full, independent and impartial inquiry to establish whether Colonel Gadhafi was killed during combat or after he was captured," the group said Thursday.
Amnesty urged the NTC "to ensure that all those suspected of human rights abuses and war crimes" get humane treatment and are given fair trials if captured. That includes Gadhafi's family members and his inner circle.
Mahmoud Jibril, Libya's transitional prime minister, said Gadhafi was captured alive and unharmed Thursday as fighters overran his hometown of Sirte. But a gunbattle erupted between the fighters and Gadhafi loyalists as his captors attempted to load him into a vehicle, Jibril said, leaving Gadhafi with a wound to his right arm.
More shooting erupted as the vehicle drove away, and Gadhafi -- overthrown in August -- was shot in the head, Jibril said. Gadhafi died moments before arriving at a hospital in Misrata, Jibril said, citing the city's coroner.
NATO said Friday that Gadhafi was in a convoy it struck in the Sirte area Thursday and the action "likely contributed to his capture."
A NATO official said Gadhafi loyalists were "boxed in" to one particular area of Sirte, an area scouted by NATO drones and rebel fighters. The airstrike destroyed "multiple vehicles" and NATO members believed Gadhafi was in the convoy but not directly hit.
As for the late despot's burial, Jibril said DNA samples confirmed Gadhafi's identity, and the International Criminal Court -- which had issued an arrest warrant for the ousted dictator on war-crimes charges -- has agreed to allow Gadhafi's burial.
Mahmoud al-Shammam, NTC's minister of information, said the burial will be delayed for few days to allow ICC officials to check the body in Misrata, if they choose to do so. He said there is no dispute over where or how Gadhafi's body should be buried.
NATO forces have been enforcing a U.N. mandate to protect Libyan civilians. Although Gadhafi was eventually captured by Libyan fighters and apparently killed by crossfire, western intervention through NATO was a key factor in his downfall.
Later Friday, NATO officials were to meet in Brussels to discuss what should happen next, but it seems unlikely that any member states will want a protracted involvement.
Deputy U.S. State Department spokesman Mark Toner said Thursday that the operation was "near its end," while French Foreign Minister Alain Juppe told French radio station Europe 1 early Friday that "the military operation is finished."
Also killed Thursday were Gadhafi's son Motassim and his chief of intelligence, Abdullah al-Senussi, said Anees al-Sharif, a spokesman for the NTC's military arm in Tripoli. Other reports say al-Senussi was captured. Jibril said Gadhafi's defense minister, Gen. Abu Baker Younes, also died.
Al-Shammam said forensic reports for both for Moammar and Motassim Gadhafi have been prepared and copies of these reports were sent to government officials in Tripoli.
Saif al-Islam Gadhafi -- son of Moammar Gadhafi -- is still alive and is being followed by revolutionary fighters, a senior member of National Transitional Council said Friday.
"We know the area where he is, and for sure he'll be captured very soon," Mohammed Sayeh told CNN.
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