By Dominica Sanda
SYDNEY, May 13 AAP: NSW's police commissioner has vowed to champion harsher penalties for harming his officers after a failed bid to launch a High Court appeal over the sentence of the mentally ill killer of detective Bryson Anderson.
Three High Court judges on Friday refused to grant the Director of Public Prosecutions leave to appeal last year's reduction of Mitchell Barbieri's minimum sentence from 26 years to 15.
Barbieri pleaded guilty to the 2012 murder but the substantial reduction was granted in December after the NSW Court of Appeal found the original sentencing judge erred when considering his severe mental illness.
The High Court said there had been no error of legal principle in the appeal court's decision.
Commissioner Mick Fuller said he acknowledged the decision but was "devastated" by it and would continue to champion for harsher sentences for people who harm police officers.
"Like every police officer, I am devastated by the decision," he said in a statement on Friday.
"Bryson was the finest police officer. He was decorated and dedicated.
"He deserved to go home to his family at the end of his shift."
Police Association of NSW acting president Tony King said his members were "disgusted" by Friday's decision.
It suggested crimes were prosecuted in a legal rather than a justice system, he said.
Then 19-year-old Barbieri was sharing mental delusions with his mother, Fiona, when he stabbed Det Insp Anderson twice in the chest with a hunting knife during a siege at the pair's rural northwest Sydney property.
Police seized a large volume of material from the squalid, isolated home, among them letters to world leaders including the Russian president.
They revealed "a complex delusional belief system alleging corruption, persecution and perceived grievances of a wide-ranging nature", according to a psychiatrist.
One of the judges, Justice Carolyn Simpson, said Barbieri's "mental illness diminished his moral culpability to a very significant degree".