A gunman who staged a siege in the Queen Street Mall five years ago is the sole suspect in a stabbing murder north of Brisbane.
Lee Matthew Hillier, 39, is wanted over the death of father and former soldier Nathan Frazer, who died from wounds to his chest and face on a Murrumba Downs road early on Thursday.
In 2013, Hillier held police at bay in a dramatic siege in the heart of Brisbane. He was handed a four-and-half year jail term for the crime.
Detective Inspector Damien Hansen said it was possible Hillier was armed, and warned people not to approach him. It's believed he is still in the Brisbane area.
"He's shown a propensity for violence," Detective Inspector Damien Hansen told reporters.
"Do not approach him."
Mr Hansen also revealed that a 19-year-old woman who called police on Thursday morning, hysterical and seeking help, was known to the victim.
He would not reveal the nature of that relationship, but said the victim, the woman and Hillier were all known to each other.
The woman is continuing to assist police.
"She has provided us with a version ... they all have an association," he said.
The murder weapon is yet to be found.
Mr Hansen would not comment on whether Hillier - who he described as a transient person - was on parole.
Columns of workers and shoppers fled the Queen Street Mall in March 2013, when Hillier produced a gun.
News crews captured the dramatic siege, screening live footage of a heavily tattooed man who'd taped a gun to his hand. At one point the gunman held the weapon to his throat.
The siege ended when police shot him with bean-bag bullets.
At his sentencing hearing in January the following year, Hillier told the court he never meant to hurt anyone when he took an unloaded semi-automatic pistol into the mall.
He said he had relapsed into drug addiction after an earlier stint in prison and "things just spiralled out of control".