Kimberly Noyes has been found not criminally responsible for the death of John Fulton.

A judge has found Kimberly Noyes, 43, not criminally responsible because of a mental disorder in the slaying of a 12-year-old autistic boy in Grand Forks, B.C.

John Fulton disappeared from the front step of his family's condominium in August 2009. His body was found two days later in Noyes's townhome just a few doors away, in the southern Interior town.

Noyes admitted to police that she killed Fulton in her condo with a kitchen knife. Her videotaped confession was not challenged during the trial, which wrapped up Friday in Rossland, B.C.

Judge Mark McEwan found she was not responsible for her actions because of her mental state at the time of the killing.

Noyes's lawyer Deanne Gafar said the judgment is reasonable under Canadian law.

Gafar said that for a person to be found criminally responsible, they must voluntarily and intentionally commit the crime.

"In this particular case, [Noyes's] mental disorder is not an excuse, it's an explanation," Gafar said.

"The finding of not criminally responsible is an additional element to our normal findings of either guilty or not guilty. Not criminally responsible is an additional ground that is based in our criminal law and has been so for centuries."

Noyes will be sent for psychiatric evaluation by a panel of three doctors within 45 days. She will be held in custody indefinitely, until experts rule she is no longer a danger to the public.

Suffered from mental illness

During the trial, both the Crown and the defence lawyers said Noyes was mentally ill at the time of the killing.

Medical experts testified that at the time of the homicide, Noyes was bipolar and severely depressed, had gone off her medication and was hearing voices.

The court heard Noyes had been treated in hospital several times over the years and her mental illness was well-documented.

One forensic psychiatrist, Dr. Shabehram Lohrasbe, testified there was "no shadow of a doubt" that Noyes has a "major" mental illness.

The court also heard from her eldest daughter and other psychiatrists who had treated Noyes about her delusion that she had to "sacrifice" her youngest daughter and then resurrect her.