MANKATO -- The man accused of murdering his ex-wife last March in front of their three children in a Mankato park will use mental illness as part of his defense.

34-year-old Joel Marvin Munt (left) appeared in court today as his attorney argued to have his statement to police thrown out.

At question is whether Mankato Police Officer Doug Fredricks, then a detective, continued questioning after Munt requested a lawyer.

While being questioned today by prosecutor Pat McDermott (right), Fredricks says he first saw Munt being led into the downtown Public Safety Center by another Mankato police officer. Fredricks describe Munt, at that point, as being very passive. Fredricks testified that he assisted in taking away Munt's shoes and belt before he was placed into their "hard interview room".

When Fredricks entered the room to being questioning Munt, he says he found him "lying on the floor, crying and sobbing."

Under cross examinatio by defense attorney Scott Cutcher (left), Fredricks admitted at one point early on, Munt referenced an attorney.

On the stand, Fredericks recalled Munt saying something to the effect of "I should have a lawyer here, for all the good it should do."

The prosecution introduced several pieces of evidence today including the taped interview. It wasn't, however, played in court today.

During the interview, Munt told Fredricks that the "system let him down" when it came to protecting his children from Svetlana Munt's abuse.

Cutcher gave oral notice of his defense today in court saying they will argue "Defense of Other" and "Mental Illness."

In "Defense of Other", Cutcher will argue that in Munt's mind, to prevent any further abuse of his children he had to shoot her. Cutcher says Munt belived that to be true because of his mental illness.

A three week jury trial has been set to begin with jury selection on Monday, August 15, 2011.