The Minnesota Department of Corrections says that law enforcement believes a prisoner at its correctional facility in Lino Lakes murdered a fellow inmate on Thursday.

According to a news release from the agency, a 63-year-old man serving a 19½-year sentence at the prison was found unresponsive in his cell about 10:30 a.m. Thursday. Medical staff and outside emergency personnel attempted lifesaving efforts, but the man was declared dead about an hour later.

Department spokesman Andy Skoogman said a 42-year-old man serving a life sentence is the lone suspect. The suspect is under administrative segregation, Skoogman said.

The victim's identity has not been released. The Midwest Medical Examiner's Office will conduct an autopsy to determine the cause of death.

The Lino Lakes prison has been placed on modified lockdown status while the investigation is completed. That means inmates are restricted to their living units. The department's Office of Special Investigations is investigating what happened with help from the state Bureau of Criminal Apprehension and Lino Lakes police.