Police believed a 15-year-old boy posed a threat to their lives when they shot him dead, a Victorian coroner has found.
Tyler Cassidy was shot dead when three police officers fired at him as he allegedly advanced on them enraged and armed with two knives during a standoff at a Northcote skate park in December 2008.
State Coroner Jennifer Coate found Tyler was not acting voluntarily and was "overwhelmed by his emotions".
The Cassidy family had submitted to the inquest into his death that the force used was disproportionate in the circumstances, but Judge Coate said that submission did not accord with a realistic view of the evidence for the situation.
"Even if Tyler had been stationary for one second, and (a witness) is the only one who says so, the evidence of what happened up until that point gives little meaning to a pause of one second," Judge Coate said on Wednesday.
"What is more likely is that the three members all fired in rapid succession as, consistent with their evidence, they observed Tyler continuing to advance on Leading Senior Constable (Colin) Dods with knives held in such a way that Leading Senior Constable
Dods' life was being put in apparent immediate peril, given he was on a platform that had dropped and uneven surfaces which could have caused him to lose his footing any moment."
Delivering her finding from a seven-week inquest, Judge Coate said there was no single cause for Tyler's behaviour on the night.
She said his dramatic fluctuations in mood were caused by a combination of the recent anniversary of his father's death, alcohol, his youth and the perceived rejection of his friends.
Tyler had texted a friend to say he was in the "worst mood ever" shortly before he died.
Judge Coate found there was an urgent need for police training to focus on how to deal with vulnerable young people such as Tyler.
"Tyler's tragic death must forever be the clarion call for Victoria Police," she said.
She found the officers involved in the shooting "acted within the limitations of their training".
Among her recommendations, Judge Coate said an independent, legally qualified person should be present when police are interviewed by other police over incidents involving deaths.
She also recommended that Victoria Police arrange a suitable welfare person to deal with families after an incident like Tyler's death.
Victoria Police Deputy Commissioner Kieran Walshe said police had already undertaken an extensive review of operational tactical safety training since the 2008 shooting, but he was eager to read the coroner's findings and would be open to making further changes to training.
"We have a very strong (training) component now about dealing with people with some form of mental impairment or mental health issue," he told reporters in Melbourne as the finding was delivered.
"We've also increased the focus around cordon and containment of critical incident scenes.
"We've increased the focus around verbal communication to enable our people to be able to de-escalate situations, to settle them down, to calm down the situation and achieve a resolution hopefully without recourse to the use of force.
"Where we need to, we'll take further action about how we make sure our people are well trained, can do their job, but also deal with these issues that they deal with many many times every week."
