After a long stand-off with police at Sydney's Lindt Cafe back in December of 2014, Man Haron Monis fired his weapon at a group of six escaping hostages.
New South Wales coroner Michael Barnes says that is the moment officers should have known the time for talking was over.
"The 10 minutes that la psed without decisive action by police was too long. Tori Johnson was executed in the meantime before the decision to enter the cafe was made."
Mr Barnes has handed down his findings from an inquest into the siege that resulted in the deaths of hostages Tori Johnson and Katrina Dawson.
The coroner concludes commanders relied on flawed advice from negotiators, who overestimated their chances of a peaceful solution and underestimated the risk Monis posed.
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"The negotiators and the consultant psychiatrist continued to advise commanders that negotiations were progressing, that the stronghold was calm, that Monis's behaviour was not consistent with Islamic State methodology, he was merely 'grandstanding.'"
New South Wales police commissioner Mick Fuller told the ABC he accepts that assessment - albeit, with the benefit of hindsight.
"In hindsight, knowing everything we know now, New South Wales police should have gone in earlier. But, again, hindsight is a wonderful thing."
When police did move in after Tori Johnson was shot, Monis was shot dead as well, but Katrina Dawson was wounded by fragments of a police bullet and later died.
Michael Barnes has ruled the two police shooters did not fire excessively or indiscriminately.
"Even if every aspect of the response adopted had ben executed to the highest possible standard, there is no certain that the outcome would have been any better, that more of the hostages would have left the cafe alive."
Despite the shortcomings detailed in his report, Mr Barnes stresses the blame for the deaths and injuries caused that night is entirely on Man Haron Monis.
Mr Barnes says Monis created an intensely dangerous situation and deserves to be the sole focus of condemnation.
But Mr Johnson's former partner, Thomas Zinn, says, while he respects the police officers' bravery, he and Mr Johnson's family remain deeply affected by what he calls "systematic failures."
He points to what he calls failures both before and during the siege.
"The pain deep in our hearts from losing Tori is as strong now as it was in December 2014. Everybody who knew Tori would agree that we lost a guardian angel that night."
The coroner is also critical of how Monis had been on bail at the time, awaiting trial for 46 offences - including being an accessory to his ex-wife's murder.
And Mr Barnes accuses police of failing to keep the families of the hostages well-informed during the siege.
Among the report's key recommendations are better family liaison policies for high-risk situations and reconsidering the police philosophy of "contain and negotiate."
It also calls for an overhaul of police negotiator training and creating a specialist group of counterterrorism negotiators.
