An inquest into Sydney’s deadly cafe siege has found extensive failings within the police and justice system.

In December 2014, gunman Man Haron Monis held 18 people hostage inside a Lindt cafe until police stormed the building 17 hours later.

A coroner on Wednesday ruled it was a “terrorist incident” for which Monis was solely responsible.

However, he said authorities had made major errors – including not acting moments before a hostage was killed.

Cafe manager Tori Johnson died immediately when shot by Monis, New South Wales Coroner Michael Barnes said.

When officers entered the building, they shot Monis dead, but stray police bullet fragments killed a second hostage, barrister Katrina Dawson.

Mr Barnes ruled police were ill-equipped to handle the siege, relied too heavily on a sole psychiatrist, and employed a “contain and negotiate” strategy which failed.

He also savaged an earlier decision allowing bail to Monis, who had been charged with 43 sexual assaults and being an accessory to his ex-wife’s murder.

The findings

Although Mr Barnes stressed the deaths were “not the fault of police”, he found failings with their actions, including:

• a 10-minute delay between Monis firing his first shot and police entering the building, allowing Mr Johnson to be “executed in the meantime”
• relying on “erroneous” advice from a psychiatrist who did not have sufficient terrorism expertise
• underestimating the gunman’s preparedness to kill or injure hostages
• allowing eight calls by hostages to police to go unanswered
• having some confusion around the lines of command.

Mr Barnes said a prosecutor had given inadequate information when Monis faced an earlier bail hearing over his ex-wife’s murder.

“That [prosecution] solicitor erroneously advised the court that Monis did not have to show exceptional circumstances before he could be granted bail on the murder charges,” Mr Barnes said.

Monis, an Iranian-born Australian citizen, had pledged allegiance to so-called Islamic State (IS) not long before the siege.

“It remains unclear whether Monis was motivated by Islamic State to prosecute its bloodthirsty agenda, or whether he used the organisation’s reputation to bolster his impact in pursuit of his own ends,” Mr Barnes said.

Emotional build-up

On Monday, the families of Mr Johnson and Ms Dawson criticised a police command tactic to intervene only if the gunman killed or injured someone.

“I’ll never be able understand how you can make a calculated decision that you wait for someone to die,” Mr Johnson’s mother, Rosie Connellan, told the Australian Broadcasting Corp (ABC).

However, New South Wales Police Association acting chief Tony King said the inquest had scrutinised police officers “as if they were on trial”.

“For some lawyers the focus appeared to be not just to attribute blame but moral culpability, twisting words to belittle experienced officers,” he wrote in a long post on Medium.

How the Sydney siege unfolded

• A gunman enters the cafe early on 15 December 2014 and has a coffee before holding a gun to manager Tori Johnson’s head.
• The gunman is identified as Man Haron Monis, an Iranian self-styled Muslim cleric given asylum in Australia.
• Monis already faces a string of criminal charges, including sexual assault and being an accessory to the murder of his ex-wife.
• Several hostages manage to escape the cafe which is surrounded by hundreds of armed police.
• Police commandos storm the cafe in the early hours of 16 December, after Monis shoots Mr Johnson dead.
• Monis and cafe customer Katrina Dawson die in the police operation.

In depth: Timeline of events