Joseph Banis' plea agreement also means he could be paroled after 20 years in prison, The (Louisville) Courier-Journal reported. Banis entered the guilty plea Monday, admitting he was involved in the murder of James Carroll, 37.
Jeffrey Mundt, who is also charged with the killing, testified during Banis' trial, blaming him for the 2009 killing and saying he helped hide the body out of fear. Banis's lawyer, in his closing argument, suggested Mundt was the killer.
Mundt is scheduled to go on trial soon.
Prosecutors said Banis and Mundt killed Carroll to rob him after a night of three-way sex and drugs, then jammed the body into a plastic container before burying it in the basement of the home they shared in Old Louisville.
Mundt's lawyer, Steve Romines, said he was not concerned about Banis' testimony.
"We look forward to the opportunity to cross-examine a witness actually convicted of the murder that he's testifying about," he said.
Carroll's body was discovered months after his death.