CARSON CITY, Nev. — Nevada’s top prosecutor says a 22-year-old prison inmate has pleaded guilty to attempted murder of a guard and battery with a weapon on another inmate in separate cases.

State Attorney General Adam Laxalt says Justin Tyler Mendoza pleaded guilty Monday at Lovelock Correctional Center, and could face a maximum of four to 30 additional years in state prison on the two felony convictions.

Mendoza’s sentencing is scheduled April 2 in Lovelock.

Mendoza’s pleas acknowledged he used a sharpened ballpoint pen to stab another inmate last April 11, and that he used a sharpened piece of plastic to injure a corrections officer trainee on May 19.

Mendoza, of Elko, was in prison for his conviction as an adult in a June 2011attack on a fellow Nevada Youth Traning Center detainee.