He found the Ministry had placed the social worker in a position where she didn't have the capacity to deal with the complex needs of the teen and his family.
"To a large extent, the shortcomings of the afternoon ... were a consequence of the Ministry's failure to provide the necessary resources to deal with the difficulties that day," the findings said.
"This meant that all possible preventive steps were not taken that day. It is unfortunate that they were not because [the] suicide might have been prevented had they been taken."
The teenager first told his family therapist of his suicide plan and the information circulated to his CYF social worker, her supervisor, his principal and school counsellor.
None of them told his parents or took urgent preventive action and he died hours later. Though the teen was in the custody of CYF at the time, he was living with his parents.
Children's Commissioner Andrew Becroft previously described it as a "terribly sad" case and "all too familiar territory" after a 2014 review of case worker workloads showed high demands and a lack of supervision.
That was echoed in the Chief Social Worker's review of actions leading up to the teenager's death. According to the report the teen and his family were initially assigned three case workers but that whittled down to one within months. The remaining social worker was supervised by five superiors in two years.
The key findings included CYF's lack of engagement with the child and his parents, little culturally responsivness to the family- whose first language was not English- a lack of capacity to deal with the teenager's needs, a lack of experience in working in suicidal ideation, and a lack of cohesiveness between organisations involved in the boy's care.
That included his therapist, his social worker, and his school.
"While all the agencies considered in this review 'shared' concerns, there was less evidence of agencies sharing responsibility for considering what these concerns could mean and how best to manage a response," the report said.
"Instead, agencies appeared to work in silos- passing on information (mostly) and considering their part in the response effectively complete, when in reality information sharing was incomplete and uncoordinated.
"The need for information sharing across services is a recurring theme in reviews and policies- however an unintended consequence on the emphasis of passing information on is that this can be associated with having passed on responsibility as well."
CYF was replaced with the Ministry for Children after questions were raised about its performance in a Government initiated 2015 expert panel review.
Oranga Tamariki is now developing a suicide prevention strategy with other organisations. It was giving young people more face-to-face time with its social workers, hiring more staff and giving staff more training, it said in a statement.
Oranga Tamariki regional manager Nicolette Dickson told the Herald the teen's death had been felt deeply by staff and it was important they learned from it.
"We agree with the Coroner and Chief Social Worker that Child, Youth and Family could have done more on the day in question to recognise the immediacy of the risk to this young person," she said.
"The children and young people we work with often have a complex range of issues, so it is important we are vigilant and responsive to any potential suicide risks."
Where to get help:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider.
However, if you or someone else is in danger or endangering others, call police immediately on 111.
• Lifeline: 0800 543 354 (available 24/7)
• Suicide Crisis Helpline: 0508 828 865 (0508 TAUTOKO) (available 24/7)
• Youthline: 0800 376 633
• Kidsline: 0800 543 754 (available 24/7)
• Whatsup: 0800 942 8787 (1pm to 11pm)
• Depression helpline: 0800 111 757 (available 24/7)
• Rainbow Youth: (09) 376 4155
• Samaritans 0800 726 666
• If it is an emergency and you feel like you or someone else is at risk, call 111.
