A man who stabbed a sleeping 17-year-old to death because he believed he had raped his sister will spend at least the next decade in jail.
Ned Gronow was stabbed 12 times as he slept in his northern NSW home in the early hours of June 25, 2022.
Mr Gronow's mother, who was also sleeping nearby, discovered her barely alive son moments later in what she described as a "bloodbath".
A 21-year-old man was sentenced on Tuesday to 18 years in jail after pleading guilty to murder.
He received a non-parole period of 12 years, backdated to June 26, 2022, making him first eligible for release in 2034, when he will be 30.
Prior to the murder, the man received a text message from his younger sister suggesting Mr Gronow had raped her, the NSW Supreme Court was told.
The man asked another person for Mr Gronow's address, telling them: "I'm going to cut Ned's lungs out and kill, hang his f***ing mother."
In a fit of rage and under the influence of drugs and alcohol, the then 18-year-old walked several kilometres to his target's home, where he stabbed him until he believed he was dead.
In sentencing the man, Justice Helen Wilson said whether or not the sister's claim was true "is something which this court cannot and need not determine".
"This proved to be the feature that caused the offender to commit his shocking crime," Justice Wilson said.
Forensic psychologist Alison Cullen said in a report prepared for the court that the man had an entrenched sense of himself as his sister's protector, which prompted his actions.
At several points in delivering the sentence, Justice Wilson paused to check if Mr Gronow's distraught mother, who was present in the courtroom, was able to continue.
"Because Ned died a violent death, she was not even able to hold her son in her arms, but was required to leave him lying alone on the floor of his bedroom in a home that has become a crime scene," the judge said.
"She feels that her own life as she knew it ended with her son's death. Her grief and despair were palpable in the courtroom."
The killer addressed Mr Gronow's parents in court on Monday, sobbing and apologising for taking their son's life.
"I took your boy's life. It's my utmost regret. Sincerest apologies. I'm sorry," he said.
The man said he would receive his sentence "with an open and accepting mind".
"I came here an 18-year-old kid and will leave a 30- or 40-year-old man and the whole world would have moved on without me," he said.
"And that's OK because I need to pay for what I did."
