– An expected guilty plea from the man accused of killing his three daughters in their River Falls, Wis., home last summer was put on hold Wednesday.

At issue was what kind of evidence could be allowed at trial if Aaron Schaffhausen decides to admit to the crimes but still argue to a jury that he shouldn’t be held responsible for them because of his mental health.

St. Croix County Circuit Judge Howard Cameron said attorneys would file court papers on the question and meet again at a hearing Thursday afternoon.

Schaffhausen attorney John Kucinski told the Star Tribune on Tuesday evening that his client was considering pleading guilty to committing the crimes while still maintaining that he is not responsible because of mental disease or defect.

Kucinski argued in a document filed Wednesday morning that pleading guilty should mean excluding all testimony of alleged threats to Schaffhausen’s ex-wife or the children, as well as all autopsy and crime scene data “since the sole issues are, at the time of the crimes, was Aaron suffering from a mental illness.”

Prosecutor Gary Freyberg had raised concerns in a Tuesday letter to the judge. “The defendant should be questioned thoroughly about why he is changing his plea,” Freyberg wrote. He argued that much of the evidence that would have been presented at trial to determine guilt should still be allowed to determine mental responsibility.

The trial is scheduled to begin Monday.

In a filing Wednesday, Freyberg wrote that “evidence that a defendant attempted to conceal a murder weapon, to alter the crime scene, to destroy or conceal evidence all have a strong tendency to show that defendant understood the wrongfulness of his conduct.”

Evidence is relevant, he wrote, to show the degree of planning and preparation by Schaffhausen, whose “very presence in River Falls, at a time when he was supposed to be at work in Minot, North Dakota, bringing with him multiple sharp instruments, is evidence of conscious choices tending to show planning and preparation.”

Schaffhausen, 35, is charged with 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.

During Wednesday’s hearing, attorneys argued over several procedural points, including what photos of the girls may be shown. His ex-wife, Jessica Schaffhausen, sat in on the court proceedings for the first time Wednesday, at times watching Aaron Schaffhausen while he sat motionless and stared straight ahead.

Asked why his client didn’t change the plea Wednesday, Kucinski said after the hearing “we really have to wait until tomorrow because we have to confirm stuff,” adding they had to look up some laws and see how the judge would rule.

Freyberg said his team will be ready for either kind of trial Monday.

“It is a difficult, challenging landscape when you’re not sure which phase of the case is going to start in … five days,” he said. “We will be prepared to present whatever is necessary to see that justice is done.”