HUDSON, Wis. - A pretrial hearing for a North Dakota man accused of killing his three daughters was delayed for several hours Wednesday as attorneys discussed a possible guilty plea that never materialized.

Aaron Schaffhausen has pleaded not guilty by reason of mental disease or defect in the last summer's slayings of his daughters in the River Falls, Wis., home where they lived with Schaffhausen's ex-wife. His attorney, John Kucinski, said in a court filing Tuesday that Schaffhausen might concede killing the girls while maintaining an insanity claim.

When St. Croix County Circuit Judge Howard Cameron convened Wednesday's hearing, he said no plea change would happen at the hearing. After handling several logistical matters, he set another pretrial hearing for Thursday.

Afterward, Kucinski declined to say why Schaffhausen didn't change his plea and said he didn't know what the defense would do at the Thursday hearing.

Assistant Attorney General Gary Freyberg, the lead prosecutor, said it would be inappropriate for him to comment on what held up the change in plea. He said the state was prepared to go forward with trial Monday in two phases, the first on whether Schaffhausen killed his daughters and the second on his insanity claim.

Schaffhausen, a construction worker from Minot, N.D., faces three counts of first-degree intentional homicide. His daughters, 11-year-old Amara, 8-year-old Sophie and 5-year-old Cecilia, were found dead in their beds July 10. Their throats had been slit, and gasoline had been poured in the basement in an apparent attempt to burn the house down.

Prosecutors allege Schaffhausen did it to get back at his ex-wife, Jessica, because he was bitter over their divorce and angry because he thought she had begun seeing another man.

Jessica Schaffhausen was in the courtroom Wednesday but took no part in the proceedings. Aaron Schaffhausen, in an orange jail jumpsuit and shackles, sat impassively at the defense table, staring at the table or floor for most of the hearing.

Freyberg maintained that any concession by Schaffhausen of his guilt should not keep prosecutors from using evidence they have planned to use during that phase. The assistant attorney general wrote that evidence of motive, intent and planning could directly rebut Schaffhausen's claim that mental disease or defect makes him not responsible for his actions.

"If the killings were motivated by revenge, anger, jealousy, etc., they are not the product of a mental disease or defect," he wrote.

According to a criminal complaint, Schaffhausen texted his ex-wife on July 10 to ask for an unscheduled visit with the girls, and she consented. Schaffhausen arrived and sent a baby sitter away.

About two hours later, he called his wife and, according to the complaint, told her: "You can come home now because I killed the kids."