A Sioux City man who admitted killing his wife a year-and-a-half ago has died in prison. A spokesperson for the Iowa Department of Corrections says 51-year-old Timothy Leon Sohler died Wednesday at University Hospitals in Iowa City.

He was an inmate at the Anamosa State Penitentiary. The cause of death is unknown. Results of an autopsy and toxicology testing could take up to six weeks.

Sohler was sentenced to 25 years in prison last November after pleading guilty to attempted murder in Woodbury County. He was originally charged with first-degree murder in the stabbing death of his wife, Susan, in their home on December 22, 2008.