The man accused of killing his three daughters in their River Falls, Wisconsin, home argues police failed to follow proper procedures when they arrested and interrogated him. Aaron Schaffhausen sat impassively through a day-long court hearing, while his attorney argued the issue. The Hudson Star-Observer reports the judge is expected to rule by mid-January.

Before then, Schaffhausen's public defender must decide whether or not to enter a plea of not guilty by reason of insanity. St. Croix County Circuit Judge Howard Cameron has set a December 14th deadline for entering such a plea.

Authorities say Schaffhausen returned to River Falls in July from his new home in North Dakota and killed his three daughters, then called his ex-wife and told her what he had done. He turned himself in to law enforcement while a manhunt was underway. At a hearing in August Schaffhausen refused to enter a plea. The court entered a not guilty plea on his behalf.