Forster-Jones, 24, has since admitted in court he acted with reckless indifference when he murdered Eden Waugh by shooting him in the chest through the door of his home in Watson.

Forster-Jones then callously stepped over the dying man's body and went on to pillage the home and drag the man's girlfriend across the room by her hair.

It was nothing but an inhumane act of cowardice, Eden Waugh's mother Elaine Waugh told the ACT Supreme Court at a sentence hearing on Tuesday.

"I cannot find adequate words to convey to you, Peter Forster-Jones, my utter desolation, heartbreak and bewilderment at the cold-hearted murder of Eden."

For the 37-year-old's murder, two violent home invasions and various assaults and acts of violence, Justice Michael Elkaim jailed Forster-Jones for 40 years, five months and 23 days.

The judge set a non-parole term of 25 years that means Forster-Jones will be eligible for release in 2043, when he will be nearly 50 years old.

The whole case was pervaded by the evils of illicit drug use, Justice Elkaim said.

Eden Waugh's Watson home, from where he dealt drugs, was first invaded in September 2016 by three men, including Forster-Jones, who were carrying a gun, a machete and a metal pipe and who demanded drugs while assaulting and threatening the people inside.

Forster-Jones shot Eden Waugh during a second home invasion months later on November 3, in what prosecutors said was an attempt to seek revenge, terrify the man who they believed had "ratted" them out after the first home invasion.

During the second home invasion, one man broke his back when he jumped from the third floor window to escape, while the home invaders had stepped over Eden Waugh's dying body and dragged his girlfriend across the room by her hair.

At a sentence hearing in the ACT Supreme Court on Tuesday, prosecutor Anthony Williamson said the conversations captured by undercover police showed Forster-Jones' complete lack of remorse and his intention to continue committing crimes.

"Clearly, killing another human being has not subdued his criminalistic impulses," he said..

Mr Williamson said he continued to try to justify his conduct.

Forster-Jones also spoke to the officer of "saving" his co-accused by killing Eden Waugh.

But a barrister for Forster-Jones, Richard Davies, told the court the man was still young, and that this was not a case where the court should write him off and throw away the key.

He said the crimes were completely out of character for a man with only one minor offence, driving with illegal drugs in his system, on his criminal history.

Justice Elkaim was surprised by Forster-Jones' lack of a criminal history, and found he had been "swept up by the effects of the drugs he was taking" as well as a desire to impress the unsavoury people he had taken up with.

The judge did not put much weight on Forster-Jones' comments to the undercover police officer, saying they reflected an attitude of bravado and not necessarily how he truly felt.

Forster-Jones had also, Justice Elkaim said, expressed conflict about Eden Waugh's death to the undercover officer, saying, "no one really deserves for that to happen to them in their own house".

The judge said that although the home was involved in illegal drugs, that did not mean the criminal underworld could act according to its own rules.

Outside court, Eden Waugh's father David and his mother Elaine remembered their son as a loving and gentle man, an artist and a musician, who could pick up a broken guitar and make it sound great.

In statements to court they had expressed confusion about the circumstances in which their son was brutally murdered.

Elaine Waugh does not believe in closure. "You just have to learn to live with it," she said after the sentence.

"There's no door that shuts and we go, oh that's fine, that's all over. It's something as parents you carry for the rest of your life."

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