MADISON, Wis. - A North Dakota construction worker accused of killing his three young daughters is expected to enter an insanity plea in a Wisconsin court.
Aaron Schaffhausen of Minot is scheduled to appear at an arraignment Tuesday in St. Croix County Circuit Court.
Prosecutors expect him to enter a plea of not guilty by reason of mental disease or defect. His attorney has declined to comment on a possible plea.
Schaffhausen faces three first degree murder charges as he is accused of killing his children, 11-year-old Amara,8-year-old Sophie and 5-year-old Cecilia while he was visiting them in their home with their mother's permission two weeks ago.
The girls' mother, Schaffhausen's ex-wife Jessica Schaffhausen, was at work during the visit but gave Aaron permission to be there.
Investigators say Schaffhausen showed up at the house the girls shared with their mother in River Falls for a surprise visit last month while their mother was out. They believe he killed the girls and then called Jessica and told her to come home because her children were dead.
A medical examiner ruled that all three girls had been stabbed, and the youngest had been strangled.
Schaffhausen and the girls' mother divorced in January.
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