Deer Lodge, MT -

A Montana State Prison inmate convicted of killing another inmate in an argument over stolen headphones has been sentenced to life in prison without the possibility of parole.

District Judge Brad Newman sentenced 32-year-old Shawn Duncan Morrison Thursday in Deer Lodge.

Morrison was convicted in November 2012 of deliberate homicide for killing 53-year-old Julio Santiago Jr. in September 2011. Court records say Santiago was punched, choked and his face and neck were cut.

Newman sentenced Morrison to a consecutive 10 years for the use of a weapon and 15 years for possession of a weapon by an inmate.

Defense attorney Tom Bartleson sought the possibility of parole, saying his client suffered from mental illness. State officials countered Morrison has personality disorders that do not meet the law's definition of mental illness.