A man who admitted to killing his nine-year-old son in 2016 has been jailed for up to 41 years.

Canberra man Graham Stuart Dillon pleaded guilty to murdering son Bradyn in court last year.

Dillon was sentenced to 36 years for the murder, with the remaining years added for grievous bodily harm and assault charges including choking and threatening to kill.

He showed no emotion as the details of his horrifying crimes were read out in the ACT Supreme Court today.

Bradyn died of brain injuries after being repeatedly struck in the head in separate attacks.

The court heard Bradyn was subjected to months of bashing and threats to be killed by his father in what Justice John Burns said would be "aptly described as murder" over perceived misbehavior, including lying and stealing lollies.

During the trial last year, the court heard shocking details of Bradyn's abuse over a prolonged period of time.

In the months leading up to his death, the boy was burnt with cigarettes, punched in the stomach and thrown against the wall.

The boy's father carried out his final attack on February 15, 2016, when he knocked the child unconscious.

The court heard Bradyn was knocked to the ground, kicked and punched - resulting in a bleed on his brain.

The boy lay for hours untreated before an ambulance was finally called to their Jacka home. He later died in hospital.

"The offender evidently made unsuccessful attempts to revive Bradyn, but did not call for emergency assistance," court documents state.

According to the documents, he then conducted Google searches on what to do if someone is knocked unconscious, before researching online shopping and accessing pornography.

The papers detail more than 60 injuries to Bradyn's head and body, claiming "the violence was often punishment for a real or imagined infraction of discipline".

After initially pleading not guilty, in August last year Dillon admitted responsibility for his son's death.

Outside court today, Bradyn's mother Rachel Jones praised the justice system but said nothing will bring back her little boy.

"No sentence that could have been handed down today against this vicious and cowardly predator could ever give me satisfaction," she said.

"We have lost our little boy in the most callous and brutal ways."

Dillon was immediately returned to custody.

He will be eligible for parole in 2048.

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