Wise County Commonwealth's Attorney Ron Elkins said Robert Gleason Jr. was "involved" in the death of 26-year-old Aaron Alexander Cooper. Gleason has not been charged in the death.
Cooper died Wednesday in the recreation yard at the maximum security Red Onion State Prison.
Elkins is awaiting a report from the medical examiner, but he says authorities believe Cooper was strangled.
Gleason was serving life for another murder when he killed his cellmate at Wallens Ridge State Prison last year. He pleaded guilty in May and is scheduled to be sentenced Aug. 31.