Prosecutors expect not guilty plea in sisters' deaths - WKOW 27: Madison, WI Breaking News, Weather and Sports

RIVER FALLS (WKOW) -- Prosecutors anticipate the man accused of killing his three young daughters in River Falls will plead not guilty by reason of mental disease or defect.

Aaron Schaffhausen, from North Dakota, faces three counts of first-degree intentional homicide and one count of attempted arson in the deaths of his daughters. Police found 11-year-old Amara, 8-year-old Sophie and 5-year-old Cecilia dead in their River Falls home last month.

In court filings, Assistant Attorney General Gary Freyberg wrote that he believes Schaffhausen will enter a not guilty plea by reason of mental disease or defect when he's arraigned next week.

Schaffhausen's attorney, John Kucinski, told the Eau Claire Leader-Telegram newspaper several weeks ago that he plans to show Schaffhausen was delusional and depressed before the slayings. He declined to comment when reached by telephone Thursday.

Schaffhausen is currently being held in the St. Croix County Jail on a $2 million cash bond. His arraignment hearing is scheduled for August 28.