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Jahche Broughton used the bat to fracture Karen Aim's skull in the early hours of January 17, 2008.
The 27-year-old Orkney woman, who had fallen in love with New Zealand and worked in a local glass shop, was walking home after a night out in town when she was killed.
In March 2009, Broughton became the youngest person in New Zealand to be sentenced to life imprisonment.
He will not be eligible for parole until 2021.
Yesterday, Taupo coroner Wallace Bain said the case raised the issue of "what a 14-year-old boy is doing out on the streets of Taupo in the small hours of the morning with alcohol and predisposed, it seems, to such violent behaviour".
He questioned how this could happen and whether there were any previous signs in Broughton's behaviour.
"It raises the standard question of supervision and whether there should be any criminal or other responsibility for those who were supposed to be supervising him."
Broughton was living at his maternal grandparents' home, with his mother, aunt and uncle, at the time of the murder. He had previously been placed with a foster family, but returned after a few months.
Broughton had viciously attacked another woman in similar circumstances less than two weeks before he killed Ms Aim.
Just after 2.30am on January 5, he struck 17-year-old trainee chef Zara Schofield on the head with a rock and continued to bash her repeatedly as she lay helpless on the ground.
On January 17, he was smashing windows at Taupo Nui-a-Tia College with the baseball bat when Ms Aim walked past.
In sentencing Broughton, Justice Graham Lang said he must have seen her, followed her on his bike and killed her on the street corner 50m from her home where her body was found.
Broughton's mother, Eugenie, could not be contacted yesterday but earlier she told the Herald there had been signs.
"I don't want to blame it solely on alcohol or drugs because there's also a behaviour that leads to those sorts of actions. I could say that it's hormone-related. It's a whole lot of things, really.
"It's society, it's our lifestyle. I don't know, I think maybe I spoilt him too much ... Because all he ever got was love and support - still does."
Detective Sergeant Anthony Manunui, who was second in charge of the murder inquiry, said Broughton had been in trouble for minor offences, but there was nothing to suggest he would commit such serious crimes.
Karen Aim's father, Brian, earlier told the Herald he had read the report, which Dr Bain sent him.
"I just agree with the report fully."
Parents cannot be held legally responsible for their children's crimes but some police officers and school leaders have suggested the law should be changed.
In February, Whangarei police commander Paul Dimery called for the parents of a youth gang to be held legally accountable.
In March, Secondary Schools Association president Patrick Walsh said parents should be held responsible for their children's actions.