The teenager who set fire to her ex-boyfriend's house, killing his mother, had been a concern for authorities for eight years.
The coroner's inquest into the death of 49-year-old Pukekohe woman Lynette Chapman began in the Auckland District Court today.
On January 20, 2009, Tonia Bennett, 17, had been drinking and taking drugs at her CYF-supervised home.
She was angry with her ex-boyfriend Brad Chapman - with whom she had been in a relationship for three weeks - and decided to take some of his clothes to his home across the road and set them on fire.
Brad, 18, and his two brothers, Todd, 20, and Cole, 13, were staying at their father's that night.
At about midnight Bennett soaked a T-shirt in absinthe and tried to set it on fire on Ms Chapman's doorstep, just across the road from where she lived.
When it did not fully light, she used a spare key to enter the home where she soaked a sweatshirt in absinthe and ignited it in the stairwell of the house.
Bennett later told police she could hear a television going and knew Ms Chapman regularly slept with it on.
The mother of three was overcome by smoke and died in her second-storey bedroom.
In 2010, Bennett pleaded guilty to murder and two counts of arson and was sentenced to life imprisonment with a minimum non-parole period of 11 and a half years.
An 18-year-old man, who acted as a lookout on the night, was jailed for two years for manslaughter.
Coroner Morag McDowell said the inquiry would use the facts established by the High Court but was more concerned with the circumstances of the murder and whether there was adequate supervision of Bennett.
The court heard how Child Youth and Family became aware of Bennett when she was 9 after she displayed attention-seeking tendencies and had anger-management problems.
There were also issues with "compulsiveness, destructiveness and lying" but no substantial action was taken at the time.
After Bennett's parents separated in 2006, she went to Australia with her father and younger sister, where she ended up in temporary care after behavioural issues.
However, she absconded and returned to New Zealand to live with her mother.
After being passed around CYF-approved caregivers in Auckland and Wellington, Bennett was referred to Youthlink who rented a property in Pukekohe for her, which was regularly visited by caregivers.
Shortly before the incident, Youthlink had informed CYF it did not want to continue caring for her as she was becoming increasingly difficult to deal with and there were few staff who were prepared to deal with her.