Iranian-born Man Haron Monis, 50, had a history of extremism and violence and was on bail for a string of charges, including sexual offences and abetting the murder of his ex-wife.
Last month, he posted a message in Arabic on his website pledging allegiance to “the Caliph of the Muslims”, which some have interpreted to mean the Islamic State militant group.
Yet he was allowed to roam free and take 17 hostages at a cafe in the heart of Sydney on Monday, unfurling an Islamic flag during a 16-hour siege which left him and two innocent victims dead. Six others were wounded.
The gunman, who Abbott called “a madman”, was well known to both state and federal police and the domestic spy agency ASIO, but was not on any counter-terrorism watch lists.
“These are the questions that we’ll be having our officials ponder because he was a person who had been of interest to our security agencies,” the prime minister told ABC radio.
“We want to know why he wasn’t being monitored, given his history of violence, his history of mental instability, and his history of infatuation with extremism.”
The threshold for placing someone on a watchlist boils down to whether they are regarded as being at risk of committing violence against innocent people.
Abbott said he intended to publish a report into what happened in the lead-up to the siege, why Monis was not on any watchlist and how he got a gun, vowing complete transparency.
“The system did not adequately deal with this individual. There’s no doubt about that, and this is why we’ve got to constantly learn the lessons of everything that happens,” he said.
“The public will have access to me; they’ll have access to ministers. And my intention certainly would be to publish a report on this so it will be out there for all to see.”
While police eased an exclusion zone around the scene of the drama after a large swathe of the central business district was shut down as the siege unfolded, security across Sydney has been stepped up, with hundreds more officers on the streets.
Commander Michael Fuller, who is heading Operation Hammerhead, said it was to ensure the public “it’s okay to feel safe and the police are next to them during these difficult periods”.
“It’s a high-visibility police operation that will focus on putting police out and about in public places, sporting events, transport hubs and other areas that police deem necessary leading up to the busy New Year’s Eve period,” he added.
Fuller said there had been no intelligence to suggest a repeat of the incident was likely, but “we’ve all seen the look on the faces down at Martin Place and there is fear”.
“And the best way to ensure people that they are safe is to have a strong police presence.”
Fuller revealed there had been some “hate and bias crime” since the siege despite more than 40 Muslim groups condemning the hostage-taking and the use of the flag.
But he stressed they were isolated and paled in comparison to the outpouring of support for both the victims and the Muslim community.
The siege has touched a nerve among Australians, who began laying flowers at a makeshift memorial in the heart of Sydney’s financial quarter on Tuesday, and the floral tribute has only grown bigger.
“When you get out into the middle and you’re there amongst that emotion, it’s overwhelming,” said Cat Delaney, who was handing out tissues to mourners. (AFP)