HUDSON, Wis. — The day his ex-wife could legally remarry, Aaron Schaffhausen hopped aboard a train and left North Dakota to go back to Wisconsin. The next day, he cut their three young daughters’ throats, wrapped their necks with his spare T-shirts, and tucked them into bed.
Prosecutors used those details in opening statements Tuesday to press their case that Schaffhausen was driven by revenge — not mental illness — and decided the best way to punish his ex-wife was to kill their girls. His defense attorney argued that Schaffhausen sank into depression after the divorce and couldn’t control his emotions or actions.
Jurors will weigh those contrasting portraits to decide if Schaffhausen, 35, was sane when he killed his three daughters, 11-year-old Amara, 8-year-old Sophie, and 5-year-old Cecilia, on July 10 last year in River Falls, Wis.
In his opening statement, Wisconsin Assistant Attorney General Gary Freyberg said Schaffhausen was angry because he thought his ex-wife had begun seeing another man.
Besides the timing of the killings — right after a six-month waiting period for remarriage written into the couple’s divorce decree — Freyberg cited as evidence of Schaffhausen’s planning that he brought the tool he used to cut his daughters’ throats with him from North Dakota and tried to destroy evidence afterward.
Freyberg said Schaffhausen lied several times about his trip to River Falls. He told fellow employees in North Dakota, where he was a construction supervisor, that he would be at work July 9 and 10. And he told his ex-wife that he drove a work van to St. Paul so it could be repaired, Freyberg said.
‘‘Help was available if he wanted it. He didn’t want help — he wanted revenge,’’ Freyberg said. ‘‘He was so angry and so bitter that he decided to punish her in a way that he calculated would cause her the most harm possible.’’
Defense attorney John Kucinski described Schaffhausen as a man in decline after the divorce. He described him as an obsessive person: first with work, then with school after he quit his job. After dropping out of school and moving out of the house, his obsession turned to his ex-wife, Jessica, Kucinski said.
Kucinski said Schaffhausen was prescribed several different antidepressants following the divorce and sometimes mixed alcohol with his medication; his behavior grew increasingly erratic. He would call his ex-wife up to 30 times a day, and once threatened to tie her up and choose which of their daughters to kill, Kucinski said.
He said Schaffhausen told a cousin in a phone call that he was ‘‘thinking of slitting the girls’ throats.’’
The cousin, Jessica Schaffhausen, and others urged Aaron Schaffhausen’s family to make him get mental health treatment or even commit him to a mental institution, the defense attorney said.
Of the killing themselves, Kucinski said: ‘‘When he’s with Cecilia, something happens. The next thing he recalls, there’s a lot of blood. The girls’ throats are cut.’’
According to court papers, Schaffhausen then poured gasoline in the basement and tried to set the house on fire. His wife told police he called her and told her: ‘‘You can come home now; I killed the kids.’’
Attorneys for both sides used that call to support their cases. Kucinski said his client was distraught. Freyberg said Schaffhausen was taunting his ex-wife.
Schaffhausen’s concession that he killed the girls transformed his trial into one that likely will determine whether he spends the rest of his life in prison or is committed to a psychiatric institution from which he might someday be released.
Three psychiatrists who evaluated Schaffhausen will eventually testify in the case. One said he was not guilty by reason of insanity. The other two said Schaffhausen likely understood what he was doing.
Aaron and Jessica Schaffhausen divorced in January 2011. Court papers indicate their marriage had been rocky for several years and finally broke up after she discovered he had lied about going back to school.
Jessica and the girls stayed in the house in River Falls, a community of about 15,000 people about 30 miles east of the Twin Cities. Aaron Schaffhausen took a construction job in Minot, N.D.