A U.N. report on the assassination implicates the government of the former president, claiming Pakistani officials at the time "failed profoundly" to protect her.
The U.N. report on the Dec. 27, 2007, death of Bhutto in Pakistan's garrison city of Rawalpindi also dismissed a subsequent investigation into her death as prejudiced.
Bhutto was killed 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 investigators said they have a 32-point questionnaire that they were sending to Musharraf in London, Pakistan's Dawn newspaper reports.
"We have prepared a questionnaire for the former president to record his statement," said Waseem Ahmed, an investigator in the Bhutto probe.
Kamal Shah, Pakistan's former interior minister, said there was adequate security for the former prime minister and aides to Musharraf said he had nothing to do with security details.
A Pakistani team blamed the Pakistani Taliban for the assassination, though the U.N. panel said that was an effort to divert the investigation, Dawn added.
Bhutto was allegedly wary of Musharraf as she attempted to return to power in Pakistan.
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