Read on: Accounts emerge of Gaddafi's final moments
“We found that he was alive and then he was dead. And as far as we can tell there was no fight," he said.
"Was there a fight when transporting him to Misrata? We don’t know. But there was definitely a time gap and I am sure an investigation will happen.”
Burshan’s comments, contradicting Prime Minister Mahmoud Jibril's account that Gaddafi was killed in crossfire, comes a day after the UN called for a probe into the death.
Christof Heyns, the UN Special Rapporteur on extra-judicial executions, told Al Jazeera on Friday that the manner of the deposed Libyan leader's killing could be a war crime.
Heyns said a proper investigation into the exact events surrounding Gaddafi’s death was a key test for Libya’s future as a democratic and accountable state.
On Saturday, people continued to line up in Misrata to view the body of Gaddafi, kept in a freezer as speculation remained rife as to when and where he would be buried.
Al Jazeera’s James Bays, reporting from Misrata, said people were lining up to see the room where the bodies of Gaddafi, his son Mutassim, and his defence minister were put on display.
"There is a constantly moving queue of at least 300 people here. People are being let in in small groups into the compound."
One of the people waiting to see the body, told Al Jazeera:"He [Gaddafi] ruled us for 42 years. In his life, it was impossible to see him, so we are here to take a look."
Also on Saturday, Prime Minister Jibril said he would step down, fulfilling a pledge he had made earlier to do so once the country was liberated from Gaddafi’s rule.
Outlining the timetable for Libya’s first elections after Gaddafi’s fall, Jibril said he would give up the post once his government took full control of Libya, which would be announced in a "liberation" ceremony on Sunday.
“The first election after the liberating of the country, which should take place today, should be within a period of eight months, maximum. The first elections to constitute what we call the national congress of Libya, or some sort of parliament you know."
"This national congress would have two tasks - draft a constitution, on which we would have a referendum, and the second to form an interim government to last until the first presidential elections are held," Jibril said.
Gaddafi, who ruled Libya for more than four decades, and his son Mutassim, were killed on Thursday when NTC forces overran his hometown of Sirte. The fate of Saif al-Islam, another one of Gaddafi's influential sons, remains unknown.