Channel 2 Action News has learned accused killer Hemy Neuman changed his plea on Friday to not guilty by reason of insanity.

Neuman is charged with killing Rusty Sneiderman on Nov. 18 in the parking lot of his son's Dunwoody preschool.Court records allege Sneiderman’s wife, Andrea, was having an affair with Neuman, her direct supervisor at GE Energy.

Channel 2 investigative reporter Jodie Fleischer learned the change in plea means Neuman’s defense team will acknowledge that he shot and killed Sneiderman, but his lawyers will argue that Neuman did not know right from wrong at the time.

"This is our notice to the court that what this trial is about is not what happened, but why it happened. It is our notice that this is about the people who are involved and how this transpired," defense attorney Doug Peters told Fleischer. "This case is not about whether or not he pulled the trigger. He is the one who did the shooting. The question is, and what is provided by Georgia law, is what was his mental capacity at the time?"

6 p.m.: Accused Dunwoody killer to use insanity plea

If the jury find’s Neuman not guilty by insanity he will still be sentenced to a mental health facility until the court deems him eligible for release, officials close to the case told Fleischer.

"We have had Mr. Neuman evaluated by the best and they feel very, very confident in their diagnosis in the case which of course will be revealed," Peters said.

The attorney for Hemy Neuman's wife, Ariela, said she was devastated by the decision to enter the insanity plea. "She always believed the evidence from the District Attorney, but to hear it come from the defense really brought it home," said Esther Panitch. "I don't think anyone wants to believe their spouse is capable so there's always some scintilla of hope that they couldn't have done this and this wipes out this hope."

Attorney Seth Kirschenbaum who represents Andrea Sneiderman, Rusty Sneiderman's widow, released a statement late Friday that said, "We are relieved that Mr. Neuman has admitted that he killed Rusty Sneiderman. This was a cold-blooded, premeditated murder, however. Hopefully, the prosecution is prepared to rebut his insanity defense."

Neuman’s trial is set to begin Oct. 17.

Previous Stories: August 25, 2011: Dunwoody murder suspect’s wife takes stand August 16, 2011: Police: Dunwoody Killing Case Directed Away From Suspect June 29, 2011: Hotels, Van, Fake Beard Listed As Key Evidence In Dunwoody Slaying