CASSOPOLIS -- An Edwardsburg man has entered a plea of guilty but mentally ill to a charge of second-degree murder in the June 2012 stabbing death of his sister, Cass County Prosecutor Victor Fitz reported Tuesday.

Fitz said the plea, entered Monday by Edward Hensley in Cass Circuit Court, is treated the same as a guilty plea but includes mental health treatment during imprisonment. The 60-year-old could receive as much as life in prison.

Martha Sexton was found dead in her home in Mason Township, west of Union, on June 29, 2012. Hensley was arrested later that day in Elkhart.

He was ordered to undergo a forensic exam the next month and was deemed competent in March. But a month later, he was ordered to undergo yet another exam to determine if he was sane at the time of the slaying. A subsequent report determined he was sane but mentally ill.

The latter report triggered yet another exam requested by Hensley in which a psychiatrist concurred he was sane but mentally ill.

Sentencing has been set for Dec. 20 before Judge Michael Dodge.