The case of Donella Knox, jailed for four years for the murder of autistic daughter Ruby, mirrors New Zealand's most famous autism death - that of Casey Albury, a 17-year-old killed by her mother in 1997.

Janine Albury-Thomson, from Feilding, was tried for murder, and then convicted of manslaughter, and sentenced to four years' jail.

Albury-Thomson also felt she had run out of options - that any hope of happiness for Casey seemed impossible, so she did the unthinkable in an attempt to set her daughter free.

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Following a public outcry, the New Zealand Court of Appeal reduced her sentence to 18 months.

It raised questions about the support for autism in New Zealand, and led to an inquiry by Professor John Werry, which resulted in a range of guidelines about diagnosis, treatment and support.

Just days before the death, advocate Wendy Duff told the Herald dozens of families were unable to get respite or residential support.

"How long before a mother gets killed or a child gets killed?" she had asked.