WAUSAU — A 56-year-old Athens man who sexually assaulted a mentally ill woman at a Schofield assisted living facility after visiting a family member living at the home will be sentenced in June.

John Niemann entered a no contest plea Thursday in Marathon County Circuit Court to a single charge of second degree sexual assault of a mentally ill victim. Niemann is free on a $10,000 cash bond.

The investigation began in February when employees at Copperleaf Assisted Living reported they had discovered Niemann naked in bed with a resident at the facility. Niemann was not himself a resident of Copperleaf, but was visiting a family member with dementia when the assault occurred.

The victim, whose age was not released, was declared incompetent in April 2017 and is unable to consent to having sex due to her diminished mental condition, according to court documents. The police report states that the woman was living at the facility for elderly assistance.

Niemann admitted being naked with the woman and told police he “made a bad decision,” but denied having sexual intercourse, according to the police report.

A presentencing investigation is underway and will be used to assist Circuit Judge Greg Strasser determine an appropriate sentence during a June 4 hearing. The charge carries a maximum penalty of 40 years in the Wisconsin Prison System.