Haji Turkistan Baetani, who describes himself as the former right-hand man of Mehsud, told Pakistan's news channel Geo News he overheard Mehsud ordering his agents to slay the notorious former leader.
He later claimed Mehsud was an agent of the United States, which he said explains why the U.S. military has not targeted the Taliban leader with missile strikes from unmanned aerial drones.
Baetani claimed he was offering the information on Mehsud because of the leader's ties to Western agents and for overseeing suicide operations on Muslims.
Islamabad and U.S. intelligence officials had stated their belief that Mehsud played a role in the Bhutto assassination.
Bhutto was assassinated during a campaign rally in Rawalpindi as she led the Pakistan People's Party opposition movement against President Pervez Musharraf in 2007. Asif Ali Zardari, her widower, emerged from the opposition to become the next president of Pakistan in September 2008.