CRESAPTOWN, Md. (AP) — Authorities are investigating the slaying of a western Maryland prison inmate convicted of multiple rapes in Anne Arundel County.

The Cumberland Times-News reports that the state medical examiner has ruled Michael Armstead’s death a homicide.

The 53-year-old inmate died Jan. 9, six weeks after authorities say he was assaulted by another inmate while walking to the dining hall at North Branch Correctional Institution. An autopsy concluded he died from a head injury.

No charges have been filed in the Nov. 27 attack.

Armstead, of Brooklyn Park, was sentenced in 1992 to two life terms for raping a Glen Burnie woman in two separate attacks in 1989 and 1990. He also was convicted of a 1991 rape in Anne Arundel.

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