The man accused of killing his three daughters in River Falls, Wis., last July pleaded guilty Thursday in St. Croix County Circuit Court.
Aaron Schaffhausen showed little emotion as he answered with a quiet "guilty" three times when asked by a judge how he was pleading on counts in the deaths of each of his three girls, 11-year-old Amara, 8-year-old Sophie and 5-year-old Cecilia.
According to his public defender, John Kucinski, Schaffhausen is building a defense in which he maintains he is not responsible for the crimes by reason of insanity, the Star Tribune reports.
Schaffhausen is accused of killing his girls in the home where they lived with their mother, Schaffhausen's ex-wife. Autopsy reports indicate the girls died from "sharp force injury" to the neck. Cecilia also had been strangled, according to a criminal complaint. The bodies were found tucked in their beds.
Investigators said Schaffhausen, who had been living in Minot, had gone to the home, where the children were with their babysitter. He told the babysitter she could leave and a short time later called his ex-wife to say he had killed the kids, his ex-wife told investigators.
River Falls is a town of about 15,000 roughly 30 miles east of the Twin Cities.