In the Ana Kriégel case, Mr Justice Paul McDermott outlined the fundamental differences between how the court must consider a child and an adult convicted of murder.
He said there were very few precedents to which the court could refer. And he said this was a multi-faceted decision.
The judge said the court was required to be mindful of reality. These were children who were in the process of development, maturing and growing. They were 13 when they committed the offences and are now 15.
He said he must assess the possibility that a young offender may develop into a responsible adult, despite the awful nature of the crimes committed.
However, the court, he said, must not lose sight of the seriousness of the offending and must give weight to the fact that a child's life has been taken.
There was nothing he said to suggest either child suffered from a mental disorder.
They understood the nature and consequences of their actions.
This was, he said a murder of the most serious, disturbing and shocking type because of the extreme violence used, the ordinariness of the day, what boys that age are capable of, the swiftness with which Ana's life was taken, and the planning and calculated ease with which the crimes were committed.
There was nothing in the boys' secure family backgrounds to suggest this would happen. It was a normal sunny day, a normal working day with many families, including the Kriégels and the boys' families, anticipating a normal family evening.
Boy A
Boy A had some acceptance of responsibility and some degree of regret but the judge said he was not satisfied he had told the truth. A good deal of what he said was self- serving and not supported by forensic evidence.
The boy claimed he did not intend to kill Ana or cause serious injury to her and claimed there was an initial consensual sexual encounter. But the judge pointed to the extensive evidence of Ana's clothes being ripped and torn.
The boy cannot remember taking anything out or putting anything into the backpack he brought with him, even though there is DNA evidence linking him and Ana's blood to the items.
The judge said it was abundantly clear that Ana was in no real position to defend herself, although she had bravely tried to do so, against a sustained and vicious assault.
He said he was not satisfied the boy understood the terror she must have felt and the level of violence or that there was any real and sincere acceptance of what he had done.
Afterwards, he showed no interest in getting assistance for her or alleviating the awful anguish of her family.
Even after Ana's body was discovered he still continued to lie, and showed no remorse for what he had done, during the investigation or during the trial.
He said the boy's participation and behaviour placed his culpability at the upper end of the scale of wrongdoing, even making allowance for his age.
He had exploited Ana's previous interest in him. The attack was prolonged, callous and brutal and continued even after she was subdued and defenceless. He sexually assaulted her, using a high degree of violence.
The reports by psychologists and psychiatrists showed the boy had no mental or developmental disorder. There were no adverse events in his background and no evidence of anti-social behaviour. On the contrary, he was involved in activities with friends, school and sports.
There were no indications of callous or unemotional behaviour or anger management issues.
But the reports found he answered many questions by saying he did not know or could not remember and would need a high level of intervention over an extended period to assist him in exploring what he had done.
The judge said there was a limited appreciation of the enormity of what he had done.
His claim that they had a fight and he did not intend to cause her serious injury was difficult to reconcile with the awful violence inflicted on her in a vulnerable position.
Boy B
The judge said Boy B's parents were like Boy A's, hard working and law abiding people.
The boy was above average intelligence and again was not suffering from any mental disorder. He does not accept the jury's verdict and said he did not bring Ana to the house to be killed. The judge said the boy's parents supported him but the jury was satisfied that this was not the case.
He said the boy had a degree of empathy with the deceased and her family. But reports said it was unclear if he was fully able to process the implication of the offence.
He had no explanation for the lies he told gardaí other than being scared and ashamed of not helping. Psychiatric and psychological reports said he would need to accept responsibility for his actions.
The reports said he felt guilty for not helping and thought about this most nights.
The judge said the jury concluded the boy knew what Boy A was going to do. He had expressed a very negative view of Ana, and the judge said his disposition provided the damning backdrop to making him amenable to carry out the task of bringing her to the other boy.
In the immediate aftermath, the judge said Boy B did nothing except protect himself from discovery and left the scene without seeking help of any kind. He had no intention of helping her, he was indifferent to her plight and acted at all times to protect himself.
He then embarked on a course of deceit attempting to cover up his involvement and minimise his role.
His was a less important role in the murder he said but he was still involved in the planned murder of a 14-year-old girl with an appalling level of violence.
