Eric McIsaac has been sentenced to life in jail for murdering his brother Alex Fisher.
He must serve at least 14 years.
During McIsaac's sentencing today in Palmerston North details of what happened to the boy emerged.
He was struck with a heavy object while he slept and the Crown is asking for McIsaac to serve at least 17 years in jail for the murder, plus extra time for other offending.
McIsaac appeared in the High Court at Palmerston North wearing prison issue clothing, but Justice Collins ruled no photographs of him could be taken today.
The 26-year-old admitted murdering Alex (10) at Waitarere Beach on October 5 or 6 last year.
Alex Fisher's body was found at the beach on October 8 after his disappearance sparked a huge three-day manhunt.
During the search, police released CCTV footage showing Alex and McIsaac together in a local store on October 5.
McIsaac was arrested and appeared in court on October 7, initially charged with possessing a knife in a public place.
Crown prosecutor Ben Vanderkolk said he wouldn't go through the facts of the case because everyone who needed to be familiar with them was.
This sentencing was difficult.
In this case there was a "degree of brutality".
"It was a blow with a heavy blunt instrument."
Alex had been entrusted into McIsaac's care and McIsaac delivered blows to Alex's head while the boy slept.
The killing was inexplicable and a motive was not known.
McIsaac was disturbed and still refuses to talk about what happened.
Vanderkolk asked for a non-parole sentence of 17 years for the murder.
"Alex was taken out to an isolated spot on the coast. He was allowed to fall into sleep. He was killed and then afterwards the backpack and other items belonging to Alex was placed around the forest and hidden."
This was an attempt to disguise the killing.
"What we do know, your honour, from reports is the defendant lives with rigidity in thinking and an obsessional belief in the course of conduct he's about to embark upon," Vanderkolk said.
Such rigidity could impede treatment.
Vanderkolk said McIsaac's sentence should be reduced because he pleaded guilty.
McIsaac's mental health condition posed difficulties and might stop him from explaining why he killed Alex.
Vanderkolk referred to a victim impact statement from Alex's mother Sandra Fisher. It was written with "considerable dignity" and in a "measured way".
"It is impossible to understand the profound grief that she must feel, has felt and will continue to feel," Vanderkolk said.
Her maternal instincts extended to the care of her surviving son.
"She urges upon the court a merciful outcome."
Vanderkolk said that if McIsaac received the right treatment in the right place, Alex's death might not be in vain.
But because there was no diagnosed mental illness, any rehabilitation must come from within McIsaac.
Vanderkolk said because McIsaac was 26 and despite his indifference to his fate, any sentence shouldn't be "crushing".
Defence lawyer Letizea Ord acknowledged the trauma McIsaac caused to his family and that his mother had effectively lost two children.
The motive was still unknown and the two siblings shared a good relationship, were fond of each other and enjoyed spending time together.
"That's what makes this case so difficult. What the defence submission has always been is this was clearly not a rational act."
Ord said there was no doubt the "underlying mental health" problems, present for many years, were behind these actions.
Problems were confirmed in seven psychiatric reports and by family and friends.
But when McIsaac was first spoken to by psychiatrists, he didn't want to "plead insanity" and instead was prepared to face what he'd done.
It had become clear that McIsaac was struggling in the months and years leading up to the murder. He had told his younger brother he wanted to kill himself and had fixations about dying.
Ord said the killing wasn't calculated or committed with a high-level of cruelty, as legislation characterises the worst murders.
Alex was killed with one to two blows when asleep.
"It was clear he knew nothing."
Ord said at worst, the minimum non-parole period would be 17 years.
His mother didn't want a crushing sentence imposed but would like to see him get appropriate treatment.
Despite not explaining the offending, the guilty plea was recognition of remorse and saved the cost and stress of a trial.
While the Crown said mental illness was not a "mitigating factor", Ord said just because McIsaac didn't have a diagnosed mental illness didn't mean his sentence shouldn't be reduced as a result.
Justice David Collins outlined what happened.
On October 5 2015, McIsaac's mother took him to Waitarere. At one point he broke into a property in the town and removed bedding and a wood splitter.
After going to the shop the pair went to the beach, where Alex fell asleep in the bedding.
"After Alex fell asleep you struck him twice in the head with a wood splitter. Alex would have died immediately and wouldn't have known what happened."
Alex's body was left on the beach.
The next day McIsaac called his mum from a phone box and said he was distressed and needed to talk.
His mother arrived and the pair walked around the beach. McIsaac did not help police search for Alex.
"Your conduct is impossible to comprehend, particularly given the close relationship you had with Alex," Judge Collins said.
