But State Coroner David Whittle has stopped short of ruling that the 13-year-old's death was preventable.
He said the circumstances related to the death of Zhane Chilcott in 2016 were complex and multifactorial, and the question of whether the boy's death could have been avoided was therefore complicated.
Mr Whittle said among the failures in Zhane's case were missed opportunities for early intervention before he went into care, missed opportunities to deal with the trauma associated with multiple placements and, in the period close to his death, multiple missed opportunities to address his psychiatric issues.
"An analysis of those missed opportunities does not lead with certainty to the conclusion that Zhane's death by suicide was preventable," the coroner said in his findings on Thursday.
"I do find, however, that there were a number of missed opportunities in Zhane's case to moderate the chances of death by suicide.
"The cumulative effect of all those failings was to increase his risk of suicide.
"Had those failings not occurred, it can only be said that the risk of Zhane taking his own life must have been reduced."
At the opening of the inquest counsel assisting Sally Giles said the teen had been in some type of state care or foster home since he was about 12 months old.
She said his short life was marked by significant placement instability leading to minimal opportunity to develop meaningful and secure relationships with the adults who cared for him.
Ms Giles said Zhane had also suffered from a myriad of behavioural issues in care and at school, sparked by significant traumas and a lack of help at critical moments in his life.
At one stage he was placed with an experienced foster carer in SA's mid-north where he was said to have flourished, had begun to attend school regularly and had been nominated for a leadership role.
But when the carer said he could not continue to look after the boy without an increase in funds, authorities had refused to provide extra money.
Instead, Zhane was placed in a residential facility at a greater cost over a three-month period than what the carer had asked for over a full year.
In his findings, Mr Whittle recommended that a risk register be established for children in state care which would record all threats or incidents of self-harm.
He also called for a review of payments to family-based foster carers in a bid to increase the number of people willing to take children in and recommended children in care have their contact with biological family members considered in a meaningful way at least once every 12 months.
In relation to Indigenous children, Mr Whittle recommended that a recognised Aboriginal and Torres Strait Islander organisation, culturally connected to each child, be appointed and consulted before each foster home or care placement.
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