Evidence showing Aaron Schaffhausen's anger in the months leading up to his three daughters' deaths should be allowed at his murder  trial because it speaks to his mindset, prosecutors argued in court papers filed late Friday.

Schaffhausen is accused of killing his three daughters in the girls’ River Falls home in July. He entered an insanity plea in the case last month.

Defense attorneys filed court papers trying to exclude testimony or evidence about Schaffhausen yelling and cursing at the mother of his ex-wife, Jessica Schaffhausen, last February and March, as well as alleged threats he made to a man at various times.
Defense attorneys argued in court papers that such acts weren’t near enough in time, place, or circumstance to be relevant to the alleged crime and could prejudice a jury.
Prosecutors responded in filings late Friday that Schaffhausen’s yelling and cursing at his former mother-in-law “is evidence of the defendant’s extreme anger at Jessica Schaffhausen ... in the period not long before the crimes occurred” and shows intent and motive to commit the crimes. “These crimes were committed to extract revenge against his ex-wife, in the defendant’s own words (to other witnesses), ‘to make her suffer,’” prosecutors wrote.
Prosecutors also argue that threatening statements made toward another man “proves the defendant was angry and jealous, so much so that he was willing and intending to kill not just Jessica Schaffhausen, but a man the defendant felt was interfering with his ability to have her for himself.” The threats were made repeatedly to many people over an extended time, prosecutors wrote, arguing that they show his motive was revenge and to make people suffer for what he thought were insults and wrongdoings.
The evidence tends to rebut the defense of mental disease or defect, prosecutors argue. 
Schaffhausen, 35, is facing three counts of first-degree intentional homicide in the deaths of Amara, 11, Sophie, 8 and Cecilia, 5.  He is scheduled to appear in court for a hearing on Friday. The trial is scheduled to begin April 1.