NAUDERO, Pakistan (CNN) -- Dramatic new videotape of the assassination of former Pakistan Prime Minister Benazir Bhutto emerged Sunday, showing her slumping just after gunshots ring out.

In a video released Sunday, Benazir Bhutto, far right, appears through the sunroof before shots ring out. more photos »

The tape provides the clearest view yet of the attack and appears to show that Bhutto was shot. That would contradict the Pakistan government's account.

A previously released videotape shows a man at the right of her vehicle raising a gun, pointing it toward Bhutto, who is standing in her car with her upper body through the sunroof. He fires three shots. Then, there is an explosion.

In the latest video Bhutto is standing, and her hair and scarf appear to move, perhaps from the bullet. Bhutto falls into the car. Then, the blast. Watch tapes showing apparent gunman »

These images seem to support the theory that Bhutto died at the hands of a shooter before a bomb was detonated, killing another 23 people.

Everyone inside Bhutto's bomb-proof car lived. Those traveling with her say they saw her bleeding, and the heavily blood-stained interior appears to support their accounts. See the likely sequence of events »

The doctor who initially examined the body said Bhutto died of bullet wounds. However, the Pakistani government later said she died from shrapnel wounds from the explosion.

And, in a move that caused more confusion, the government released X-rays of Bhutto's skull and said they show she died when the force of the explosion caused her head to slam into a metal lever on the sunroof.

Bhutto's husband, Asif Ali Zardari, disputed the government's account.

"I can say confidently that she was shot," he said.

He called the government's explanation "a useless excuse, because they have to divert attention from the main subject" -- who is responsible for the killing.

Zardari also said Sunday he will serve as co-chairman of the Pakistan People's Party while their 19-year-old son, Bilawal, and newly named heir to the party leadership, finishes his studies.

"He will, of course, be kept aware of all that is happening with the party," Zardari told CNN sister network CNN-IBN. "I will be looking after the interests of the party, as a guide, as a helper, and as a friend to the party, and as a part-time leader to the party."

Once the political science student at Oxford University has been properly groomed, "then I can go and play golf," Zardari said, without specifying how long he thought the process would take.

Zardari acknowledged that his wife stipulated in her will that he was to step into her role in the event of her death. But Zardari said his decision to pass that role to their son is correct.

"I, in my political wisdom, think we need a larger symbol than myself to keep the party united with her gone," he said. "Because she could have probably not even herself imagined the reaction that her death would do to Pakistan."

He said Bhutto's assassination on Thursday has thrust Pakistan onto the verge of disintegration.

But Zardari said the parliamentary elections slated to be held January 8, less than two weeks after his wife's death, should not be postponed.

"Our demand is elections on time -- free, fair as promised," he said.

He called on opposition leader Nawaz Sharif -- who heads the Pakistan Muslim League-N party -- to also take part in the vote. Sharif has previously said he would boycott the election.

But sources within the Pakistan Muslim League-N party say they will stand with the PPP and take part in the election. Speaking on Pakistan's GEO-TV, Sharif said an official announcement on the party's decision would take place Monday.

President Pervez Musharraf's ruling Pakistan Muslim League-Q, the election commission and the interim Cabinet will hold separate meetings in the coming days to discuss the possibility of a delayed vote.

Zardari said he does not trust the government led by Musharraf to ensure the elections are indeed free and fair, but he does believe the people of Pakistan will be able to ensure that happens.

Whether his other two children will decide to enter politics "is entirely up to them," he said.

"You know children today. You cannot force them or ask them to do anything. They do what they choose to do. Bilawal has chosen this. And so will the other two -- if they choose to come and help their brother and help their father, they're welcome to. If they choose not, then I will not impose anything upon anybody."

He said Bhutto had trained Bilawal: "He realizes the enormity of the situation. So therefore, he's accepted the responsibility." Watch Bhutto's son and husband talk about the party's future »

The teenager, speaking in English at a news conference, said, "I am thankful for the CEC for imposing their trust in me as chairman of the Pakistan People's Party."

"Like all chairmen of the PPP, I will stand as the symbol of the federation," said Bilawal Bhutto. "The party's long and historic struggle for democracy will continue with renewed vigor, and I stand committed to the stability of the federation.

"My mother always said democracy is the best revenge." Watch Human Rights Watch official explain son's important symbolic role »

British Prime Minister Gordon Brown spoke to Musharraf on the telephone Sunday, and the Pakistani leader agreed to consider international support for the investigation into Bhutto's death, according to a statement from Brown's office.

Musharraf's government has previously rejected international help, specifically from Britain.

"We understand our environment better than the international community," Pakistani Interior Ministry spokesman Javed Iqbal Cheema said Saturday.

"Scotland Yard cannot investigate in Waziristan. They don't understand Pashto."

Zardari also said the PPP is asking the United Nations to investigate the circumstances of Bhutto's December 27 killing. He said he does not plan to call for an autopsy on his wife, who was buried in her hometown on Friday.

Musharraf also spoke Sunday with French President Nicolas Sarkozy, a French foreign ministry spokeswoman told CNN. After the conversation, it was announced that French Foreign Minister Bernard Kouchner will travel to Pakistan this week.

When asked about the naming of Bhutto's successor, White House spokesman Scott Stanzel said, "It is up to the political parties in Pakistan to choose their leaders."

"We believe it is important for Pakistan to confront extremists and continue on the path to democracy by holding free and fair elections," Stanzel said. "The timing of those elections will be up to the Pakistanis." E-mail to a friend

CNN's Ali Velshi and Zain Verjee contributed to this report.

All About Pakistani Politics • Benazir Bhutto • Nawaz Sharif