COLUMBUS, Ohio (AP) — One of two inmates suspected in the stabbing of an Ohio prison guard is a three-time convicted killer who boasted about strangling a fellow inmate on a prison bus.

Prisoner Casey Pigge was taken from the Southern Ohio Correctional Facility after Tuesday's attack and transferred to the state's Supermax prison in Youngstown, Joe Hale, a Scioto County assistant prosecutor, said Wednesday.

Two inmates attacked the guard in the prison infirmary with metal weapons, according to the initial incident report from the Ohio State Highway Patrol. Prisons spokeswoman JoEllen Smith confirmed a "serious inmate on staff assault" at the prison in Lucasville in southern Ohio and said the prison remains on lockdown.

Corrections officer Matthew Mathias was stabbed multiple times and is in stable condition in a trauma unit at a West Virginia hospital, said Sally Meckling, a spokeswoman for the union that represents prison guards.

In September, Pigge pleaded guilty to strangling fellow inmate David Johnson with a restraining chain as they rode on a prison transport van. He was sentenced to 25 years behind bars.

"I guess you never seen that on a bus before," Pigge boasted to the surviving inmates after Johnson's killing, according to highway patrol records.

Pigge also is serving a life sentence for using a brick to kill cellmate Luther Wade in 2016.

"Pigge denied any desire to be a serial killer, but could not promise that he wouldn't kill again," a prison social worker said after interviewing him following Wade's death.

It's not clear if Pigge has an attorney following Tuesday's attack. Steve Larson, who represented him last year in the strangling of Johnson, said Wednesday he wasn't representing him now and couldn't comment.

Pigge also is serving 30 years to life for fatally slitting the throat of his girlfriend's mother in 2008. He gave himself the nickname "box cutter" after the weapon he used to kill her.

Even before Wade's killing, Pigge's prison misconduct record ran nearly 30 pages. Over the years, he repeatedly refused to enter his cell, was found with homemade alcohol, collected contraband like razor blades, electric cords and a TV converter box and fought other inmates.

Records show Pigge was born to a 14-year-old girl who used drugs and alcohol while pregnant with him. Child protection authorities first intervened when he was just 7 days old, according to a 2009 evaluation after Pigge killed his girlfriend's mother.


Associated Press Writer Lisa Cornwell contributed to this report.