RAWALPINDI, Pakistan (CNN) -- Pakistani Taliban commander Baitullah Mehsud paid out more than $7,000, including money to purchase suicide jackets, for the assassination of Benazir Bhutto, the chief Pakistani investigator said Sunday.
Benazir Bhutto was killed shortly after this photo was taken on December 27.
Four suspects in custody said Mehsud also planned the December 27 attack, Chaudhry Abdul Majeed told reporters.
Mehsud, who has ties to al Qaeda, remains at large.
Majeed said two of the four men in custody last week confessed before a Pakistani judge that they had participated in the plot.
Many others who helped plan the attack "have yet to be arrested," Majeed said.
A day after Bhutto's death, Pakistan's government announced that Mehsud was behind the attack. The CIA later reached the same conclusion.
But two recent nationwide polls in Pakistan found a majority of Pakistanis believe President Pervez Musharraf's government had a role in her killing.
Majeed said Sunday that he announced the details about Mehsud's connection to the attack because Pakistan could formally charge him at a later date.
Two of the suspects told a judge on Wednesday that they provided the suicide bomber with a house, transportation, a pistol and the suicide jacket he allegedly used in the attack that killed the opposition leader and nearly two dozen others, Interior Ministry spokesman Javed Iqbal Cheema said.
Both were at the Rawalpindi park when Bhutto was assassinated, according to Majeed.
He said the bomber was motivated to carry out the attack because his friend was killed after Pakistani security forces stormed the Red Mosque in Islamabad last year to rout Islamic extremists holed up inside.
The two suspects told police they picked up the bomber a day before the attack at a bus depot in Rawalpindi, and the bomber stayed overnight with one of the suspects, according to Majeed.
They took the bomber to the Rawalpindi park hours before the attack to do reconnaissance, the chief investigator said. Then they went to the other suspect's house, where the bomber was fitted with the suicide vest, he said.
Majeed said the bomber was also the gunman who fired at Bhutto before detonating his explosives.
Cheema said the bomber apparently was unable to get through security to attend the political rally, so he carried out the attack as Bhutto left the Rawalpindi park.
Pakistani and British investigators concluded that Bhutto died when the force of the suicide blast slammed her head onto an escape hatch on her SUV.
Bhutto's family has dismissed the government's assertion that she was not shot by an assassin's bullet, but the family has refused to allow an autopsy on the slain opposition leader.
At a news conference last week, Cheema said Pakistani investigators "have made very good progress" in determining who planned the assassination.
"We are going to break the whole chain and we are confident we're going to reach the perpetrators," Cheema said. "We will exactly tell you who are the people behind this unfortunate incident." E-mail to a friend
CNN's Zein Basravi contributed to this report.