John Fulton was found dead inside the Forks, B.C., home of Kimberly Noyes in August 2009. (CBC)The family of a slain autistic boy has condemned B.C.'s mental health system, saying the boy's death was "completely avoidable."

Speaking publicly for the first time, the family of 12-year-old John Fulton has written a scathing letter, making it clear they believe the Ministry of Health Services let their son down.

Fulton was stabbed to death by Kimberly Noyes, 43, who lived in his neighbourhood in Grand Forks, B.C. The boy's body was found in her home two days after he disappeared in August 2009.

Last week, a judge found Noyes not criminally responsible for the slaying because of a mental disorder.

At the trial, health professionals and police testified Noyes was delusional and violent. She had been treated in hospital several times over the years and her mental illness was well documented.

In a letter sent to media on Tuesday, the Fulton family expressed frustration that Noyes had been released repeatedly, despite a clear history of violence and homicidal delusions.

"This woman knew she was mentally ill," the letter read.

"The local RCMP, mental health workers, psychiatrists, her doctor and her family knew she was ill; and despite her clearly disturbing behaviour in the months before John's death, no one thought to hospitalize her. Where was the common sense?"

Inaction 'deplorable'

The letter goes on question how it was possible that no one in a position of authority "could see a downhill spiral" which led to Fulton's death.

Kimberly Noyes has been found not criminally responsible for the death of John Fulton. (CBC)"When someone is uttering threats about sacrificing children or making homicidal comments, we believe that the government, namely mental health, should be charged with protecting the rights of the general public rather than those of the individual," the letter said.

The family said it's obvious the system is over-taxed.

"The loss of this beautiful child has been devastating to our family. The way in which he was taken from us was unimaginable. The pain we feel will take years to lessen, but will never be fully gone," the letter said.

"This senseless crime was completely avoidable. Noyes' actions were completely deplorable but mental health's inactions are equally so."