Pakistan's President Musharraf has said for the first time that murdered opposition leader Benazir Bhutto may have been shot.
Benazir Bhutto at her last rally. By the end of the day she was dead
Until now Pakistani officials have maintained that Ms Bhutto had banged her head on part of her car's sunroof.
But asked in a US television interview if a gunshot could have caused her head injury he replied: "Yes, absolutely, yes. Possibility."
She died on 27 December in a gun and suicide bomb attack while campaigning.
More than 50 people were killed in violence following her death.
The elections she was campaigning for were subsequently postponed from 8 January to 18 February.
The government said the attack had been ordered by a tribal leader in the lawless South Waziristan area on the border with Afghanistan, Baitullah Mehsud. It described him as an al-Qaeda leader.
He has denied any involvement.
'Victim to blame'
In the interview, aired on Sunday in the CBS show 60 Minutes, Mr Musharraf repeated his government's line that Ms Bhutto was to blame for her own death.
"For standing up outside the car, I think it was she to blame alone. Nobody else," he said.
According to eye-witnesses, a gunman fired at Ms Bhutto as she stood up through the car's sunroof to greet supporters after a rally in Rawalpindi. Moments later, a bomb exploded.
Ms Bhutto was taken to hospital, but doctors could not save her.
She was buried the next day, as Muslim custom demands, and no post-mortem was carried out.
Her family and supporters insist she died of gunshot wounds, rejecting the official line that she was fatally wounded when her head smashed onto part of her car's sunroof.
Mr Musharraf first signalled that the government could be distancing itself from that position last week, when he said he was not fully satisfied with the investigation.
British detectives have flown to Pakistan to help with the investigation.
Supporters of Ms Bhutto's party, the PPP, have blamed the government for her death, either because some officials wanted her dead or not enough security was provided.
But Mr Musharraf repeated that his government had given her adequate protection.
"She was given more security than any other person," he said.
A senior PPP official, Farhatullah Babar, reacted to the interview by saying the government's position on the killing had been shifting from day to day.
He said this underlined the need for a UN inquiry.
Meanwhile, Pakistan reacted angrily to reports that the US administration was considering covert operations in the country's tribal areas bordering Afghanistan.
The Pakistani foreign office said it would not let US forces hunt militants on its soil.
The statement came after the New York Times published a report saying Washington was seeking to expand military and intelligence operations in Pakistan following Ms Bhutto's death.