Kelly’s lawyers filed a motion on Friday in federal court to question Jeremiah Farmer under oath, the Chicago Tribune reported.
Farmer said in a court filing earlier this week that he attacked Kelly on August 26 in the Metropolitan Correctional Centre because he wanted to shed light on wrongdoing by the government in his own criminal case.
Farmer was able to slip away from an employee at the centre, enter a cell and repeatedly hit Kelly in the head, according to a US Bureau of Prisons report attached to Farmer’s filing.
A security officer used pepper spray to stop the attack.
Kelly, 53, faces several dozen counts of state and federal sexual misconduct charges in Illinois, Minnesota and New York, from sexual assault to heading a racketeering scheme aimed at supplying him with girls.
The Grammy Award winning singer has denied ever abusing anyone.
Farmer, 39, is facing mandatory life in prison in a racketeering conspiracy that involved a 1999 double murder, according to the newspaper.
“It appears that MCC personnel simply followed Mr Farmer, allowed him to carry out the attack, and then only intervened after Mr Kelly had already sustained serious injuries,” Kelly’s lawyer Michael Leonard wrote in the motion.
Kelly’s lawyers have been trying to have him released on bail pending his trial.
