Hassan Khalif Shire Ali was one of more than 400 ‘persons of interest’ being monitored by ASIO

The Bourke St terrorist slipped through the cracks of spy agencies, despite his movements and electronic device use being monitored. Hassan Khalif Shire Ali was one of more than 400 “persons of interest” being monitored by ASIO.

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The Bourke St terrorist slipped through the cracks of spy agencies, despite his movements and electronic device use being monitored.

Hassan Khalif Shire Ali was one of more than 400 “persons of interest” being monitored by ASIO after he was investigated for his association with other individuals linked to terrorism.

It can be revealed the ­Somalia-born Shire Ali was the subject of electronic monitoring in the wake of his passport being cancelled in 2015 over fears he planned to travel to Syria.

Somali-born Islamic terrorist Hassan Khalif Shire Ali was shot by police. Picture: @chrismacheras/Twitter

Police will use CCTV to track the attacker’s journey to the city. Picture: Nick Weeks

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The Herald Sun understands Shire Ali was monitored on his phone, email and social media after he caught the attention of police and intelligence agencies in 2015.

It remains unclear if the high-level electronic monitoring continued until Friday’s attack, but a source said Shire Ali had shown no signs of the level of radicalisation that would have justified ongoing surveillance.

“The level of resourcing just to monitor one of these guys is immense. If someone is not raising red flags through their electronic ­activities, it is unlikely they are going to be watched as closely,” a source said.

The scene after Hassan Khalif Shire Ali’s atack. Picture: Stuart McEvoy/The Australian.

Melbourne continued to mourn city icon Sisto Malaspina, of Pellegrini’s Espresso Bar, who had gone to help after Shire Ali’s vehicle caught fire before the attack.

As two other victims recover after being injured in the knife attack, police stepped up the hunt for clues.

Police will also use CCTV cameras around the city to map Shire Ali’s journey into the CBD and see if he had been scoping out the area.

Police sources have told the Herald Sun there were no reports of alarming behaviour, such as erratic driving, before the incident.

CCTV footage shows a 24 year old security guard being stabbed in the neck by Hassan Khalif Shire Ali. Picture: Nine News

Shire Ali’s phone records are being examined to see who he had been in contact with:. Picture: Supplied

People pay their respects for Sisto Malaspina who was killed in the attack. Picture: AFP

Shire Ali was known to police and smoked drugs including cannabis, but his ­offences were considered lower level.

Mobile phone footage shot by bystanders will also prove vital.

Home Affairs Minister Peter Dutton defended police and intelligence services when asked why it appeared Shire Ali wasn’t being monitored.

“Where there is not (that information), where someone makes a spur-of-the-moment decision — under the influence of drugs or ­alcohol — the police can’t contemplate every circumstance,” Mr Dutton said.

“Police did not have intelligence in relation to this person that he was about to commit an act.”