MISSOULA, Mont. — A Montana State Prison inmate serving a 45-year sentence for a stabbing death in Billings has died.

Prison officials say 57-year-old Robert Bauer died Friday at a Missoula hospital after a lengthy illness.

Bauer pleaded guilty to mitigated deliberate homicide in the December 2015 death of 40-year-old Joseph Broken Rope during an argument in which Bauer said Broken Rope owed him $150. Witnesses said Broken Rope struck Bauer, who then stabbed Broken Rope in the chest.