JACKSON, MI – A judge on Friday found a 19-year-old is not guilty in the death of his mother because he was insane at the time he used a knife to brutally kill Robin Grow, 49.

Jackson County Circuit Judge Thomas Wilson ordered David Kellen Grow back to the state Center for Forensic Psychiatry, where he will be evaluated for 60 days and then civilly committed against his will.

It is likely Grow will remain at the center, a maximum security treatment facility, for the remainder of his life, Prosecutor Jerry Jarzynka said after the Aug. 16 hearing.

A center examiner determined Grow was not guilty by reason of insanity and neither Assistant Prosecutor Jennifer Walker nor Grow’s lawyer, Andrew Kirkpatrick, disputed the findings.

“The decision reached by the judge fits the evidence and law we have in this case,” Jarzynka said.

Kirkpatrick has said from the start Grow's was a clear-cut issue of mental illness. There has never been a question of what happened, he said.

People are legally insane when they lack “substantial capacity” to appreciate the wrongfulness of their conduct or to conform it to the requirements of the law, according to the statute.

The teen was charged with open murder for killing his mother Feb. 20 inside the home they shared at 224 W. Center St.

Blackman-Leoni Township public safety Detective Joseph Merritt, involved with the case through the Jackson County Major Crimes Task Force, testified Robin Grow’s body was slashed open and her insides were spilling onto the floor. Her body was bruised and battered. A full steak knife was found inside her chest cavity. Her head, with signs of blunt-force trauma, was in a puddle of vomit, he testified.

Walker called it a “horrible, horrible murder,” the worst she has seen and probably will ever see.

Grow reported hearing commands to kill his mother, according to the forensic report, portions of which Wilson referenced.

He had a “substantial disorder of thought,” according to the doctor who completed the report.

Grow has an autism spectrum disorder likened to Asperger's syndrome, and a history of mental illness. In January, he was said to have psychosis and placed in Allegiance Health's psychiatric ward.

His father, Ronald Grow, testified he once saw his son "launch a punch" into the entrance of his room, and said: "I think I got him." When questioned about this, David Grow told his father he was referencing a demon.

He said he could "shape-shift" and called 2013 the "end of days," according to a May forensic center report. He was hallucinating early this year, his father testified.

Ronald Grow said he came home about 7 p.m. from his work as a barber to find his wife on the kitchen floor. Her body was cold, he said, speaking softly and slowly. He checked her pulse.

He said he called for his son and found him fully clothed in the bathtub with his mother’s intestines wrapped around his neck.

“I said to him… ‘Kellen, what have you done?’” Ronald Grow testified.

“I said, ‘Do you realize what you’ve done? Do you realize we are never going to be a family again? Do you realize in a couple minutes, they are going to come take you away from me too?’”

He said collected a phone, called 911 and returned to the bathroom.

His son stood. “I saw something in his eyes change.”

David Grow stripped off his clothes and his father put down the phone.

He bit into the entrails, Ronald Grow said.

His son was wet. The floor was slippery and they both fell.

The younger Grow escaped the bathroom and returned to his mother. He put his hands in her and Ronald Grow said he attempted to separate his son from Robin Grow. “I was trying to push his shoulder and pull his arm at the same time, and I couldn’t do it,” he said.

He eventually punched David Grow in the shoulder blade, and he believes the shock of it made the teen sit back in disbelief.

Ronald Grow said he pinned David Grow to the stairs and the police arrived. His son was handcuffed and placed in a Concord police vehicle.

“As soon as Kellen saw the officer, it was like a calmness came over him,” Ronald Grow said from the witness stand.

His testimony continued for more than two hours.

At times, the questions focused more on Ronald Grow than on his son.

Walker asked him about his relationship with Robin Grow. Is there a reason she had packed her bags? “I don’t even know where that comes from,” Ronald Grow responded.

She was not leaving him, he said. “There was no reason for her to.”

Walker also asked him what happened to the clothes he was wearing on Feb. 20.

Ronald Grow said he changed in an ambulance and the Michigan State Police took the articles.

She asked him if he moved his wife’s body or touched her other than to check her pulse.

“When did you wash your hands?” She asked. “I don’t know,” he replied.

He said he and his wife were married for 21 ½ years. They both lost their “youthful good looks,” but he loved her more, he said.

As the unity candle at a wedding symbolizes, they truly had become one, he said to Walker.

They were a normal family, he said.

He and his wife were told, because of his diagnosis, that their son would be “emotionally distant,” but they decided this would not be the case.

They were affectionate parents, he said, and David Grow was an honor student until the 10th or 11th grade. “He was well-liked and he liked other people.”

There were not issues of violence, he said.

“I would say, behavior-wise, he was better than average."

In the courtroom, the two were tender.

As the attorneys and observers waited for the proceeding to begin, David Grow sat in the front courtroom pew. State police troopers sat next to him and his father sat behind him, rubbing his shoulders.

During the hearing, the teen seemed attentive and alert.

With treatment and medication, the forensic center had determined him competent and able to understand the judicial proceedings.

At the close of the proceeding, David Grow blew a kiss to his supporters. The father and son embraced.

"I told him that I loved him. I told him his mother loved him," Ronald Grow said outside the courtroom.