An Ohio man serving life in prison for aggravated murder was sentenced to 86 years more for a guard's stabbing last year and a 2017 stabbing that wounded four prisoners who were handcuffed to a table and unable to defend themselves, prosecutors said.

Greg Reinke, 39, changed his plea to guilty last week on charges including attempted murder for the attacks at the Southern Ohio Correctional Facility in Lucasville, the Scioto County prosecutor's office said.

A message seeking comment was left Tuesday for his lawyer.

In a statement, county Prosecutor Shane Tieman's office said what the stabbing victims experienced was life-changing and horrifying and that it is Tieman's hope the cases "shed light on issues that need to be addressed in our penal system to better protect the personnel and inmates in our institutions."

Reinke was sentenced to 54 years for using a homemade knife to repeatedly stab handcuffed prisoners after slipping his own handcuffs — a bloody attack recorded on video that was obtained by The Associated Press.

One of the injured inmates alleged it was a setup by guards. Reinke has said officers didn't arrange it but condoned it.

Tieman said he found no evidence of a setup. No guards involved in the incident were disciplined.

Reinke was sentenced to an additional 32 years behind bars for an attack about eight months later on a corrections officer. Prosecutors allege Reinke and inmate Casey Pigge stabbed the officer 32 times.

Pigge pleaded not guilty, and his case is pending. Pigge previously was convicted of three separate killings, including strangling a fellow inmate on a medical transport bus.

Reinke was serving a life sentence for aggravated murder for a 2004 shooting in Cleveland.

Both inmates have since been moved to the Ohio State Penitentiary, the supermax prison in Youngstown.

In a phone call from the prison in January, Reinke told the AP that guards there beat him. He also alleged that prison staff mistreated him and Pigge.

Prisons spokeswoman JoEllen Smith has said there was no evidence of that. She said because of the "serious, violent" allegations against the two inmates, prisons staff were using extra security protocols with them, including searching their cells daily for weapons or contraband.