Aaron Schaffhausen may change his plea to guilty to killing his three daughters, his defense attorney said Tuesday, but Schaffhausen would maintain a plea that he is not responsible for the crimes because of mental disease or defect.

The possible change could come at a scheduled pretrial hearing Wednesday morning in Hudson, Wis.

“I think that we’re going to change the plea tomorrow, just have an insanity phase” of the trial, defense attorney John Kucinski said in a brief phone interview Tuesday. The trial begins Monday with jury selection.

Schaffhausen, 35, is facing three counts of first-degree intentional homicide in the July 10 deaths of his daughters, 11-year-old Amara, 8-year-old Sophie and 5-year-old Cecilia. A carpenter who lived in Minot, N.D., he is accused of cutting the girls’ throats while visiting them in River Falls while his ex-wife was at work.

In January, Schaffhausen added a plea of not guilty by reason of mental disease or defect, setting up a two-phase trial in which prosecutors would first have to prove he committed the crimes. If Schaffhausen is found guilty, the defense would have to prove insanity during a second phase.

People could change minds

Kucinski would not explain Tuesday why his client may change his plea. He said the possible plea is “subject to people changing their minds in the morning.”

Such a change would greatly shorten the length of the trial, which was expected to take three weeks.

In addition to the homicide charges, Schaffhausen faces a charge of arson after authorities found a gas fireplace turned on and gasoline poured in the basement.

It’s not uncommon for defendants to plead guilty to committing a crime but then plead not guilty by insanity, Marquette University Law School Prof. Daniel Blinka said.

Then the burden of proof will be on the defense to show by a preponderance of evidence that Schaffhausen had a mental disease or defect at the time of the crimes, and because of that he lacked substantial capacity to appreciate that what he did was wrong or couldn’t control his impulse, Blinka said.

A difficult path

Blinka and other Wisconsin legal experts have said it’s difficult for defendants to succeed on insanity claims.

“Anybody who engages in some of these enormously horrendous crimes we automatically think, and probably correctly so, that obviously there’s something wrong mentally with the person,” said David Schultz, a University of Wisconsin law professor emeritus. “But whether that meets the legal standard for this insanity defense is something else again. It is a relatively difficult standard to meet.”

Even if a jury agrees Schaffhausen is not mentally responsible for the crimes, he would not go free, experts said. He would likely be committed to a maximum security mental hospital, Schultz said.