Mr Bhosale was fired upon by unknown assailants on a motorbike on Koregaon area in Pune on October 11, 2009 at 10.30 am while he was on a poll campaign.
His driver Shakeel was seriously injured in the attack.
The Pune Police had charge sheeted Shakeeb Shahnawaz Alam Khan. In 2013, it intimated the court that four more persons were involved in the crime which included Rajesh Yadav, Chhota Rajan, Shankar and Vijay Shetty, CBI sources said.
They said after the arrest of Rajan on November 6, 2015, Maharashtra Government transferred 71 cases to the CBI in which his involvement was suspected.
The agency has not named Chhota Rajan in the FIR as he was not named by the Pune Police. According to rules, when the CBI takes over a case from the state police, it registers the same FIR.
The CBI is free to come up with its independent findings in its final reports which could be charge sheets or closure reports.