A psychiatric patient who fatally stabbed a man in the neck at a NSW hospital has been jailed for more than two decades.
Thomas Dillan Stone, 27, sat quietly in the dock as the Supreme Court was told he stabbed 41-year-old Robert Mitchell in the neck in February 2017 at Morisset Hospital, south of Newcastle.
Both men had been receiving treatment for psychiatric conditions and shared a room in a low-security section of the hospital.
Robert Mitchell was heard yelling "Stop, stop Tom" then "Help me, he stabbed me" before losing consciousness, the court heard.
Acting Justice Peter Hidden said although Stone's mental illness contributed to his offending, it was a serious attack and he remained a danger to the community.
"The offender attacked a man to whom he bore no ill will and who had done nothing to provoke the attack," he said.
"He intended to kill the deceased — the offence was planned."
Stone pleaded guilty to murder in November.
The judge rejected the Crown submission that Stone should be jailed for life and instead sentenced him to 23 years' behind bars with a non-parole period of 17-and-a-half years.
The court heard Stone bought a kitchen knife while he was out on day leave, took it back to the hospital and stabbed the victim three times.
He threw the knife in a nearby lake and called triple-0 to tell police he had stabbed someone.
The court heard Stone gave the operator his name and age and said he would wait for police nearby.
Asked why he had stabbed a fellow patient, he told the operator he "felt like it".
The judge referred to psychiatrist reports that described Stone's lack of empathy and logic when he carried out the stabbing.
"The irrationality of this reasoning process and the utter lack of empathy which it demonstrates are best explained by his underlying schizophrenic illness," Acting Justice Hidden said.
He will be eligible for parole in 2034.
