Tripoli, Libya (CNN) -- The United Nations and two major human rights groups called Friday for an investigation into the death of Moammar Gadhafi amid questions over the final moments of the late Libyan strongman's life.
"There seem to be four or five different versions of how he died," the Office of the U.N. High Commissioner for Human Rights said in a statement. "More details are needed to ascertain whether he was killed in the fighting or after his capture."
Questions also persisted about what would happen to Gadhafi's body. His family issued a statement Friday calling on the United Nations and Amnesty International to push Libya's new leadership "to hand over the bodies of the martyrs of their tribe so they can be buried according to Islamic rites," a pro-Gadhafi TV station reported.
Libya's interim government, the National Transitional Council, has said Gadhafi's burial will be delayed for a few days to allow International Criminal Court officials to check the body in Misrata if they choose to do so.
The whereabouts of Gadhafi's son Saif al-Islam was also in question Friday. The International Criminal Court wants the son for crimes against humanity. Revolutionary fighters said they were on his trail and would capture him soon.
Meanwhile, in Brussels, Belgium, NATO officials were scheduled to meet Friday to discuss their next steps after a military campaign that included thousands of airstrikes in Libya -- including one said to have contributed directly to Gadhafi's capture and subsequent death Thursday. Members of the alliance have said its involvement in Libya is nearing its end.
New era, challenges loom for Libyans Libyans have been elated over the demise of Gadhafi, who ruled the country for 42 years with an iron fist before he was overthrown in August. Authorities say a Liberation Day will be marked this weekend in the eastern city of Benghazi, where the rebellion first erupted. Officials plan to appoint a new interim prime minister who will establish a cabinet over the next month.
Also Friday, the international community reflected on the end of the Gadhafi regime.
"Our military played a critical role in shaping a situation on the ground in which the Libyan people can build its own future," President Barack Obama said Friday, referring to the U.S. role in the NATO operation in Libya.
Amid the jubilation, international agencies have raised issues over various and sometimes conflicting accounts of Gadhafi's death, with shaky video images separately showing a wounded but living Gadhafi and, later, his corpse, an apparent bullet wound in his head.
"As you are aware, there are at least two cell phone videos, one showing him alive and one showing him dead," the U.N. human rights group said Friday. "Taken together, these videos are very disturbing."
It called for an investigation into the circumstances of Gadhafi's death.
"More details are needed to ascertain whether he was killed in the fighting or after his capture," the agency said.
The statement by Gadhafi's family encouraged such an investigation, saying "the scenes broadcast on media outlets show that the martyrs were betrayed by the forces loyal to NATO," according to the Syrian-based pro-Gadhafi TV station, Al-Rai.
Amnesty International, meanwhile, urged Libya's interim leadership, the National Transitional Council, "to make public" all the facts of Gadhafi's death.
Amnesty also 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, chairman of the NTC's executive board, 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 was shot in the head, dying moments before arriving at a hospital in Misrata, Jibril said, citing the city's coroner.
Human Rights Watch is calling for an internationally supervised autopsy and an investigation into the death, and one of its officials said it is unlikely that Gadhafi was killed in crossfire.
Peter Bouckaert, the group's emergencies director, told CNN that fighting had ended when Gadhafi was cornered in a drainage ditch. He said crowds beat Gadhafi in what was a "humiliating end" for the former dictator.
"When he left the area, he was very much alive," Bouckaert said. "There's no reason why he should have been subjected to this kind of mob justice."
Video posted on YouTube showed a bloodied Gadhafi moments after capture, surrounded by fighters as he laid on the ground. The deposed leader appeared to remain defiant, even while encircled by men brandishing guns.
"Shame on you, you're sinning, you're sinning," Gadhafi can be heard saying on the video, according to a CNN translation.
What's next for NATO in Libya? 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, which was 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.
"At the time of the strike, NATO did not know that Gadhafi was in the convoy. NATO's intervention was conducted solely to reduce the threat toward the civilian population, as required to do under our U.N. mandate. As a matter of policy, NATO does not target individuals," NATO said in a statement.
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.
NATO forces have been enforcing a U.N. mandate to protect Libyan civilians. Although Libyan fighters eventually captured Gadhafi, Western intervention through NATO was a key factor in his downfall.
A NATO official told CNN that NATO ambassadors and Adm. James Stavridis, the supreme allied commander, will discuss ending the alliance's military mission at Friday's meeting in Brussels.
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."
Following Gadhafi's death, NATO Secretary-General Anders Fogh Rasmussen announced Thursday that the alliance "will terminate our mission," launched in March under a U.N. mandate to protect civilians. NATO's efforts have included strike sorties and airstrikes targeting Gadhafi's military resources.
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.
Mahmoud Al-Shammam, the NTC's information minister, 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.
CNN's Joe Sterling, Ivan Watson, Mohammed Tawfeeq, Barbara Starr and Chris Lawrence contributed to this report.