A Melbourne teen brutally stabbed his grandfather to death because he believed the old man was "creepy".
The 17-year-old, who cannot be identified, was jailed on Thursday for 16 years over the vicious murder in the city's outer east late last year.
The elderly man was stabbed 24 times in the back, chest, neck and head by his grandson, who had snuck out of school to kill.
The boy, who was just 16 at the time, must serve at least 11 years behind bars before becoming eligible for parole.
He initially denied any involvement, but he confessed after police linked him to the crime through CCTV, DNA and recorded phone calls and Google searches.
Supreme Court Justice Paul Coghlan on Thursday said the teen told police "fine, I did it".
"He wasn't exactly a nice man. He was also a bit of a creep and he did some things that were creepy to my sister," the teen said of his maternal grandfather.
"He didn't put his hands on her but some of the things he did shouldn't have been done."
The boy's sister said she had told him several months earlier that their grandfather stood naked in front of her four or five times when they were children and that sometimes he would give her beer.
The teen had been dropped off at school on the morning of the killing, then walked two kilometres to his grandparents' house.
The trigger on the day was unclear, Justice Coghlan said.
His grandfather, home alone, was confronted by the boy at the front door and an altercation spilled into the driveway.
He was punched to the face but broke free of the struggle and tried to run to a neighbour's house for help.
His grandson chased him into the yard and attacked him metres from the front door.
The older man fell and the boy knelt beside him, repeatedly stabbing him in the neck, back and shoulders.
A neighbour saw the incident through a window but when they went outside to help the boy had fled.
He went back to school and was not identified as the culprit until almost two months later.
Classmates were shown CCTV footage to help police identify the teen in black shoes and loose grey shorts.
He was later found to have googled "how many years imprisonment for murder in Australia".
Eight knives were found in his bedroom when police searched his home, including one with his grandfather's DNA on it.
An expert found the boy could recognise his conduct and the fatal consequences were extreme, but he gave the impression he maintained a "sanctimonious position without obvious contrition".
Justice Coghlan said the boy regretted the pain he caused his father and sister.
But he had limited regret for his mother and her extended family for the death of her father.