A radicalised Melbourne teen fatally shot after attacking two police officers with a knife had warned police they would "pay" for counter terror raids a week earlier.
Numan Haider unfurled a Shahada flag at Dandenong Plaza on September 18, 2014 following media reports raids in Sydney and Brisbane had foiled a beheading plot, the coroner's court heard.
After revealing the flag, which is a general expression of Islamic faith, he is alleged to have made threatening comments to police at the shopping centre.
"I'm not going to blow up the shopping centre today," Haider told police, the inquest heard.
"You will pay for what happened in Brisbane and Sydney today."
He later told friends he would have stabbed the officers if he had had a knife, Rachel Ellyard, counsel assisting the inquest into Haider's death, said on Monday.
Haider, 18, was killed by a single shot to the head after he stabbed a Victoria Police officer and an Australian Federal Police officer outside the Endeavour Hills police station on September 23, 2014.
He stabbed one in the arm, then the second officer in the eye before he attempted to stab the second officer in the stomach, the inquest heard.
The threats at Dandenong Plaza followed several months of escalating behaviour from Haider, who had become more interested in religious matters in 2014 and developed a resentment of law enforcement authorities, Ms Ellyard said.
From June, police began monitoring his phone, the inquest heard.
In August, Haider made inquiries about weapons, telling his friends he was going to start selling cannabis and needed to protect himself, the inquest heard.
On September 18 Haider wrote a Facebook post saying he supported the Taliban "one hundred per cent", despite the court hearing his family emigrated from Afghanistan to escape the Taliban when he was seven years old.
He would attend his local mosque twice daily and began attending the Al-Furqan mosque, the inquest heard.
Witness Sulaiman Sarwari told the inquest Haider became depressed about the situation with his family, who were not as religious.
"He would sometimes sleep at the mosque," Mr Sarwari said.
Haider's family said they were educated, moderate Muslims and believed their youngest son had been manipulated.
In a statement read to the inquest, Haider's family said they suffer inconsolable grief following their youngest son's death but did not wish to lay blame.
"They regret the police officers were harmed," the statement said.
"They regret that their beloved son and brother Numan is not with them today."
The inquest continues before coroner John Olle.
