Authorities are investigating a murder in the maximum security state prison at Jefferson City.

Mark Melton (image courtesy; Missouri Department of Corrections)

Mark Melton (image courtesy; Missouri Department of Corrections)

The Cole County Sheriff’s Department says inmate Mark Melton, 35, was assaulted in his cell by his cellmate the evening of August 19. He had been severely beaten and was taken to University Hospital in Columbia for treatment. Melton died Sunday of his injuries.

The name of Melton’s cellmate has not been released. He is described as a 33-year-old white male serving a sentence for second degree murder and armed criminal action.

Melton was serving nine years for attempted statutory sodomy in the first degree. He had been in prison since late 2009.

An autopsy on his body was performed yesterday.

The date of the assault in an earlier version of this story was incorrect, based on information that was in error in a release to the media.  That has been corrected in this version.