Blenheim mum Donella Knox jailed for murdering autistic daughter Ruby

A devoted mum murdered her severely disabled daughter in a "once in a generation" killing.

Donella Knox, 49, drugged and then suffocated her beloved daughter Ruby at their Blenheim state home on May 16 last year.

Knox was sentenced to four years' imprisonment at the High Court in Blenheim on December 16.

Ruby Knox as a young girl and a teenager. Photo / Supplied

She can now be named after a court-imposed suppression order lapsed. It also allows the heart-breaking circumstances leading up to the mercy killing to be revealed.

Knox, a solo mum, killed her daughter after a 20-year battle with her violent outbursts, round-the-clock care, poverty, and feelings of being let down by the health system.

At sentencing, Justice Joe Williams described it as a "once in a generation case".

The court heard that Ruby had been severely disabled her whole life.

At the age of 6, she was diagnosed with severe autism spectrum disorder.

It meant she couldn't talk and was prone to violent outbursts, often lashing out at her mother.

The court heard that Ruby's behaviour meant that neither of them could maintain any normal social relationships.

But Justice Williams said: "The common theme from all who knew you and Ruby was that you loved and cared for Ruby constantly, diligently, unselfishly and unconditionally. A tireless advocate with health authorities, you refused to give up."

In the six months leading up to the killing, Ruby's functioning had deteriorated and she had become even more disruptive and violent.

The court heard that Ruby Knox had been severely disabled her whole life.

Sleep-deprived and exhausted, Knox took Ruby to her local hospital's emergency department 10 times between February and May last year, claiming that her daughter was in pain but could not communicate it.

Justice Williams noted that she "felt that the medical fraternity had brushed you off".

On the fateful day of May 16 last year, Knox received a letter from doctors who could find "no obvious reason for severe pain". Knox took it to mean that further surgical assistance was unlikely.

"It seems that this letter was a trigger for your decision to take Ruby's life," Justice Williams said.

At about 1pm, Knox sedated Ruby with risperidone anti psychotic medication before placing both hands over her face and nose until her breathing stopped.

Knox then went to Blenheim police station and gave a full confession.

The Crown had argued that a jail term of 8-10 years would have been appropriate and had indicated that they would appeal the four-year sentence.

Crown prosecutor Mark O'Donaghue said Knox "did have other options" at the time, including respite care, residential respite care, and home health support.

However, a spokeswoman for Crown Law today confirmed that no appeal will be lodged.

Donella Knox in court. Photo / Pool

"Appeals against sentence must have the Solictior-General's approval and the Solicitor-General has considered this case," she said.

"Consent for appeal would only be given where the sentence imposed is wrong in principle or inadequate. The Solicitor-General's assessment was that there was no basis on which to appeal in this case."

Defence counsel Simon Shamy said there was no doubt over the love Knox had for her daughter.

But feelings of isolation and being trapped, along with the stress and anxiety over the welfare and care of Ruby, meant that she had "felt cornered into taking this most terrible action for Ruby's sake and her own".

Justice Williams said he had traversed the pair's background, and events leading up to the death, in great detail.

"In going through that exercise, I became very sure of one thing: to send you to life imprisonment for Ruby's murder would clearly be inappropriate, or in the words of the law, manifestly unjust," he said.

"Your feeling that the system had constantly failed you was long held, and genuinely and deeply felt. In your mind, Ruby's unresolved pain and the burden that placed on you... left you with no viable alternative."

Timeline

• January 8, 1996: Ruby Isabella Knox is born in Blenheim.

• October 2001: A stressed mother, Donella begins a five-year diary exploring her and Ruby's daily struggles.

• 2001: 60 Minutes films a disturbing documentary on Ruby and her mum's battles.

• 2002: Ruby is officially diagnosed as suffering from autistic spectrum disorder.

• 2007: 60 Minutes revisits the Knox family.

• 2009: Ruby undergoes surgery to have metallic spinal rod inserted to alleviate back pain.

• February - May 2016: Ruby's health deteriorates, with Donella taking her to Blenheim Hospital's emergency department ten times.

• May 16, 2016: Donella sedates Ruby was 20.5 of risperidone antipsychotic medication before placing both hands over her face and nose until her breathing stopped. Makes full confession.

• December 16, 2016: At the High Court in Blenheim, Justice Joe Williams sentences Knox to four years' imprisonment for what he says is a "once in a generation case".