Bhutto, a former prime minister of Pakistan, was killed Dec. 27, 2007, following a campaign rally for her Pakistan People's Party. She had returned to Pakistan from exile to run in January 2008 parliamentary elections.
Pakistani President Asif Ali Zardari, Bhutto's husband, called on a U.N. panel examining the assassination to question former U.S. Secretary of State Condoleezza Rice and Afghan President Hamid Karzai, among others. Zardari said the leaders had information regarding threats to Bhutto's life prior to her return to Pakistan, the Press Trust of India reports.
Other international figures include intelligence officials from Saudi Arabia and the United Arab Emirates.
A U.N. commission headed by Chilean Envoy Heraldo Munoz began investigating the circumstances surrounding the assassination of the former Pakistani prime minster in Rawalpindi in July.
Martin Nesirky, a spokesman for the United Nations, said the Munoz report was complete.
"They believe they have finished their work and that there is no need to include any further information," he said. "It is for them to consider whether they need to change their report."
The United Nations is expected to release its findings April 15.