Libya's transitional leader says decisions for a new interim government should be in place in about two weeks.

National Transitional Council head Mustafa Abdel Jalil's announcement in the eastern city of Benghazi Monday comes a day after he declared the country liberated from Moammar Gadhafi's 42-year rule at a ceremony attended by tens of thousands of people.

Libya's outgoing provisional prime minister Mahmoud Jibril had previously said Sunday that consultations were under way to form a new interim government within one month.

Mr. Jalil also announced Monday that the NTC has ordered an investigation into Gadhafi's death after the U.S., rights groups and others called for the probe.

Libyan doctors performed an autopsy on Gadhafi's body in the city of Misrata Sunday and said he died of gunshot wounds to the head and abdomen during last week's takeover of Sirte. Cell phone video shows provisional government fighters taunting and beating a wounded Gadhafi shortly before he died.

Libyan officials say the former leader was shot in a crossfire between his loyalists and provisional government forces. Fighters on the scene have acknowledged beating the ousted leader after his capture.

Meanwhile, a human rights group reporting from Gadhafi's hometown of Sirte says it has found the bodies of 53 people who appear to have been executed by fighters for the NTC during the bitter fighting for control of the city.

Humans Rights Watch said it discovered the bodies in an abandoned hotel in an area of Sirte that was controlled by anti-Gadhafi forces at the apparent time of the deaths about a week earlier. The group said the bloodstains on the grass, the bullet holes on the ground and the bullet casings scattered around the site suggest that executioners killed some, if not all, of the people at that location.

Sirte residents preparing the bodies for burial said most of the victims were local people and some were Gadhafi supporters. Human Rights Watch is urging Libya's new authorities to investigate the deaths and hold those responsible accountable.

U.S. Secretary of State Hillary Clinton says the United States would like to see a U.N. investigation of Gadhafi's killing. She said she supports the investigation that the NTC has pledged to conduct, and said it is important for a democratic Libya to begin with the rule of law and accountability.

British Defense Secretary Philip Hammond said Gadhafi's killing had “stained” the image of Libya's provisional government, and that Britain would have liked to have seen the former leader stand trial for alleged misdeeds.

Gadhafi's body remained on public display in a commercial freezer in Misrata Sunday. Details of his burial have not been disclosed.