The serial criminal faced the ACT Magistrates Court on Wednesday, when he was fined $2500 for what was described as "weird" behaviour.

The man had previously pleaded guilty to three counts of property damage, and two counts of trespassing.

Almost 20 years ago, when he was just 14 years old, he struck and killed Clea Rose while driving a stolen car during a police pursuit.

The Canberra Times has chosen to refer to the man's role in the death of Ms Rose and therefore cannot name him because he was a child at the time.

On May 1 last year, the man, then aged 33, was arrested after stealing Mr Kyrgio's bright green Tesla at gun-point and leading police on a pursuit across several suburbs.

He has pleaded guilty to aggravated robbery and is set to face sentencing for this in the ACT Supreme Court at a later date.

On Wednesday, Legal Aid lawyer Jan de Bruin, said his client was suffering from a psychotic episode when he committed a series of crimes six weeks before the arrest.

Dr de Bruin stated the man had told a report author he believed he was being chased at the time.

Prosecutor Ilsa Hattam said the crimes "would have caused significant alarm to several neighbours".

Magistrate James Lawton labelled the behaviour "very bizarre", and stated the man was "having some issue with drug use".

Agreed facts state in March last year, the man parked his car in Ainslie before he jumped a fence, climbed onto a garden shed and then onto the roof of a home.

A neighbour saw the man walking along the rooftop before jumping across to another house.

At the same time, a different neighbour was home with her children when a pizza delivery driver knocked on the door with dinner.

When she answered the door, the driver told the woman there was "a male acting in a weird manner around her residence".

The mother heard banging noises and, worried for her children's safety, called her husband to come home.

When the husband arrived, he saw the man and went to get a ladder.

Instead of accepting assistance, the trespasser ran to the other side of the roof, grabbing the water line from an air conditioner and causing it to gush water.

He then jumped into a tree and began to play with a pink armband, a telephone line and the water line.

The man jumped again, this time landing on a gazebo and causing damage.

In 2005 Ms Rose, who was 21, walked out onto the road when the boy, driving at high speed, struck her and then failed to stop.

The girl sustained serious injuries and was taken to hospital in a critical condition, before she died from catastrophic brain injuries three weeks later.