Mr Devonport was told that the group had been at the wedding of Miss Huata's mother, Beverly, and her partner Mark at the Kahungunu Marae at Raupunga. Many relatives stayed on at the marae for several days to continue celebrations.
Tyrone drank five pre-mixed vodka drinks before the crash and went to sleep in the driver's seat of the Toyota about 4am.
Two hours later, his cousin Hayden Thornton woke him and asked him to drive him home. They left, but returned seconds later to pick up Miss Huata and two others.
Tyrone told police he was still tired when he was asked to drive, and acknowledged he might have fallen asleep at the wheel.
Hayden Thornton told police he asked Tyrone to drive, and said: "Tyrone can drive and he has driven on the road before. As a group we were all pretty drunk, me included. Tyrone was okay with it ..."
About 800m from the marae, Tyrone lost control of the Toyota. Miss Huata, who was in the back seat, was not wearing a seatbelt and was ejected from the vehicle when it rolled. She suffered a skull fracture and bleeding around her brain and died a short time later.
Mr Devonport said the cause of Miss Huata's death was clear.
"A group of intoxicated persons asked a 13-year-old to drive them ... The 13-year-old was not licensed to drive, and was not at an age at which he was entitled to hold a licence to drive. Further, he had consumed alcohol, and acknowledged that he only had several hours of sleep and may have fallen asleep."
Mr Devonport said Miss Huata might have survived had she been wearing a seatbelt.
But he said everyone in the car was responsible for her death in their own way.
"Blatant disregard for the driving laws in New Zealand, directly by the driver and with the knowledge of other persons, has resulted in the death of Mary-Lee Huata. It was wrong for Tyrone to have driven, but it is equally reprehensible that other persons placed [him] ... in that position ... It is by chance only that there were not more deaths ..."
Police did not charge Tyrone over the crash because of his age at the time.
"The Children, Young Persons and Their Families Act 1989 sets out the very limited situations in which children under 14 can be charged with an offence," Mr Devonport said. "The police, following advice, did not charge Tyrone with manslaughter - a charge that can be laid against a person of Tyrone's age."
He said that there was a reason people under 16 were not allowed to drive.
"They do not have the maturity in decision-making and are a risk not only to themselves, but to other road users."
