The use of a chainsaw to terrorise a public service department last year has been likened to a horror movie, evoking "fear and terror" in the minds of fleeing bureaucrats, a court has heard.
Benjamin Dunne, 35, is being sentenced for the attack on his colleagues at the Department of Human Services in Greenway in March last year.
Dunne, the court heard, was suffering from significant mental health issues at the time and believed he was being harassed, bullied and attacked by some in the workplace.
He spoke of getting revenge and took the chainsaw into the offices on March 28.
"I had to show everyone what DHS was doing," he would later explain to a doctor.
Terrified staff fled the office building as he used the chainsaw to smash a glass security door until it shattered.
No one was hurt in the incident and the chain on the chainsaw was not working, the court heard.
Crown prosecutor Anthony Williamson said the choice of such a weapon evoked memories of a horror movie.
Mr Williamson said it was brandished in a way to instil fear and terror, causing a significant degree of alarm.
He said it was lucky none of the employees tried to disarm or tackle Dunne, and that no one was hurt as they fled.
Dunne was eventually arrested at the scene and later pleaded guilty to committing an act to cause public alarm, which attracts a maximum 10-year prison sentence.
Dunne's barrister Alyn Doig told the ACT Supreme Court on Wednesday of the significant mental health issues his client was facing at the time. Dunne was eventually diagnosed with paranoid schizophrenia.
Mr Doig said it was a "very sad" fact that Dunne had been in contact with ACT Mental Health for 14 months before the incident.
He said Dunne had no criminal record and described the attack as a "single incident in an otherwise blameless life".
The "clearly delusional thinking", Mr Doig argued, should reduce Dunne's moral culpability.
But the Crown disputed that, saying the mental health problems did not impair his ability to know what was wrong.
"He knew what he was doing was wrong. He knew it was going to have serious consequences," Mr Williamson said.
Justice Hilary Penfold will sentence Dunne next month.