The 16-year-old who raped and murdered six years old Alesha MacPhail has been sentenced to a minimum of 27 years behind bars as he finally admitted his crime.
During his trial, Aaron Campbell had repeatedly denied he abducted, raped and killed the six-year-old on the Isle of Bute last July.
But he admitted his offences to a psychologist preparing a report to the court ahead of his sentencing.
Judge Lord Matthews imposed a life sentence for the "brutal" murder.
He set the punishment part of the sentence, before Campbell can apply for parole, at 27 years.
Lord Matthews said Campbell's crime had caused "revulsion and disbelief".
He said Alesha had been violated and murdered and told Campbell he was a "cold, callous, calculating, remorseless and dangerous individual".
The judge said the teenager had shown breathtaking arrogance during the trial and had failed to plead guilty despite overwhelming evidence against him.
He said he had shown "a staggering lack of remorse".
"Not once did I detect a flicker of emotion from you," he said.
Lord Matthews said it would be for others to decide if Campbell would ever be released and there was much work to be done before that could ever happen.
During his nine-day trial at the High Court in Glasgow last month, Campbell claimed he had never met his victim and lodged a special defence naming the 18-year-old girlfriend of Alesha's father as the killer.
Campbell's confession was contained in the criminal justice social report and the criminal psychologist's report, which were prepared ahead of his sentencing.
Campbell's defence QC, Brian McConnachie, said: "Clearly the most striking thing about both reports is the fact that in the reports Campbell has admitted responsibility for the rape and murder."
McConnachie said background reports on Campbell highlighted a range of psychotic traits and expressed concerns about "sexually harmful behaviour".
Alesha, from Airdrie in Lanarkshire, was just days into a holiday when she was abducted from her bed.
She was reported missing from her grandparents' home on Ardbeg Road, near Rothesay, at 06:23 on 2 July last year.
Dozens of islanders joined the search for the child but at 08:54 her naked body was discovered in a wooded area in the grounds of the former Kyles Hydropathic Hotel.
A post-mortem examination later revealed she had suffered 117 injuries and died from significant pressure being applied to her face and neck.
The judge told Campbell: "You went into the house and then her bedroom, you removed her from there and took her to a secluded spot where you raped and murdered her in the most brutal fashion.
"It's difficult to imagine the distress her family must have suffered."
After the sentence was read out family members shouted "evil" and "beast" as Campbell was led down to the cells.