MINNEAPOLIS (WCCO) — A Wisconsin father who admitted to killing his three little girls is heading to trial Monday.

Aaron Schaffhausen, on Thursday, entered a guilty plea in the deaths of 11-year-old Amara, 8-year-old Sophie and 5-year-old Cecilia.

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The girls were found dead at their River Falls, Wis. home last July.

The trial will determine Schaffhausen’s sanity, as well as the punishment for his crimes.

If found sane, he would likley spend the rest of his life in jail.

If found insane, he would go to a mental treatment facility with the possibility of one day being released.

When Schauffhausen changed his plea to guilty on Thursday it also changed certain aspects of the trial.

It’s no longer expected to last as long since the jury will only be deciding his mental state.

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The plea change may also keep certain graphic evidence out of the courtroom.

Throughout the days leading up to the trial, Schauffhausen has remained emotionless even though his attorney says he feels remorse.

“He’s got a lot of remorse,” said John Kucinski, Schaffhausen’s defense attorney. “He’s depressed, been depressed for a long time. He’s on suicide watch.”

Prosecutor Gary Freyberg said that’s not by choice.

“He is there because he refuses to cooperate with the jail, that’s been said in court,” he said.

This phase of the trial is different than a criminal trial because the burden of proof, to prove his sanity, is on the defense not on the prosecution.

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In criminal trials, all jurors must be unanimous in their decision. However, when it comes to Schaffhausen’s trial to determine a mental state, only 10 jurors need to agree.