The gunman who brought Brisbane’s Queen Street mall to a standstill last year says events spiralled out of control.

The gunman who sent Brisbane’s central pedestrian mall into lockdown last year says he never meant to hurt anyone.

Lee Matthew Hillier, 35, told the Brisbane District Court he had no reason to cause fear to innocent bystanders when he took an unloaded semi-automatic pistol to the Queen Street mall on March 8, 2013.

Wearing a suit, the prisoner told his sentencing hearing on Thursday he had relapsed back into drug addiction following his last stint in prison and “things just spiralled out of control”.

“I wasn’t in there to harm anybody,” he said from the dock during an at-times rambling statement.

“To stand there with an empty handgun and to have 30 police stand there with revolvers facing you is very, very confronting.”

Hillier, who has remained in custody since the incident, said that leading up to the standoff his best friend “blew his own head off” in a siege but he wasn’t going to “sit there and make excuses”.

“I’d just like you to take into account that I am standing here and take responsibility for my own actions,” he told Justice Terry Martin.

Workers and shoppers fled Queen Street when the heavily tattooed Hillier produced a gun, sending the mall and surrounding businesses into lockdown.

The 90-minute stand-off ended when police shot the shirtless gunman with a combination of non-lethal and live rounds.

Witness statements read to the court said during the stand-off Hillier had appeared agitated, had often pointed the gun at himself and seemed to be frothing at the mouth.

“Get away or I will kill myself,” he yelled at one stage according to a witness statement read out by defence barrister Simon Hamlyn-Harris.

Mr Hamlyn-Harris said his client had been at “rock bottom” that day and submitted a psychiatric report that detailed Hillier’s disadvantaged background and psychological factors.

Prosecutor Belinda Merrin outlined a lengthy criminal history that included several convictions for weapon and drug possession and a string of traffic offences.

Less than two months before the siege he had blown some of his own fingers off with a homemade shotgun.

The prosecutor said Hillier’s propensity for carrying weapons in public meant he was a serious danger to community safety.

Hillier pleaded guilty to a dozen serious charges including assaulting police while armed, going armed to cause fear, and dangerous conduct with a weapon.

Some charges related to the earlier incident when he blew his fingers off.

He also pleaded guilty to a string of traffic offences and breaching bail conditions.

Justice Martin is due to pass sentence on Friday morning.