"I f---ing stabbed him," Scott Jamie Cole, 42, later told police. "I hope he's dead."

Cole slashed his own arms and face to make it look like he'd been attacked in the deadly confrontation with his neighbour Jason Hollingshed, 46, at Stuart Flats in Griffith the afternoon of February 29, 2016.

Hollingshed, who sometimes washed car windows on Northbourne Avenue, suffered wounds to his face, neck, arms and torso.

He died of blood loss.

Cole was arrested when police were called to the Light Street public housing complex, where the men lived in neighbouring units, about 4.30pm. He pleaded guilty in the ACT Supreme Court to murder.

Prosecutors argued he should serve a lengthy sentence for the "ferocious" and "frenzied" stabbing attack, but stopped short of urging a life behind bars.

"This was a violent, brutal stabbing murder on a vulnerable victim in his own home," prosecutor Margaret Jones said.

Fresh details of the killing emerged for the first time in court on Monday. A police statement of facts said the neighbours were friends before their relationship soured in the months before the killing.

Cole had taken a dose of methadone, five valium tablets and had been drinking alcohol in a neighbour's apartment when he went back to his unit and Mr Hollingshed questioned him about a broken screen door.

He yelled, "What the f--- happened to my door?", to which Cole replied he didn't know.

The pair argued before Cole went back to his unit, grabbed a kitchen knife with a 20-centimetre blade and stormed upstairs.

The court heard Mr Hollingshed said, "Scotty, what are you doing?" and Cole replied: "You're gone."

He plunged the knife into the man's neck, arms and torso as he fell to the ground. Cole continued to stab him forcefully in the neck.

Neighbours arrived to find Mr Hollingshed on the ground in a pool of blood and making gurgling sounds. They told Cole to phone police.

Instead, he went back to his unit where he washed the knife and put it back in a drawer.

He removed his bloodied clothes and put them in the laundry basket before he cut his arms and face to make it look like he'd been attacked by the victim.

Police soon arrived and Cole asked them if "the maggot" was dead. "Is he dead? I hope he's f---in' dead. Teach him to come at me."

He was arrested and later admitted to the killing. Cole told police he "did the right thing" and "that guy deserved everything he f---ing got".

He said he "took someone's life today" and he didn't "f---ing want to do it again".

Cole admitted he had "a barrage" of drugs in his system that day and described going into the victim's apartment with the knife before the attack. He said "his eyes just went real big, shit himself".

"Went boom, boom, pumped him about three or four times in the guts. So I pumped him in the sternum and I pumped him three times through the neck."

Ms Jones told the sentence hearing Cole's comments to police showed "justification and boasting" and "extreme callousness" towards his victim.

She said the offence showed little premeditation but had not been entirely spontaneous, arguing Cole had an "opportunity to stop and consider his actions".

The court was told Cole had a long history of violent offences, many involving knives.

Ms Jones argued the murder was in the upper end of seriousness but said the case did not warrant the maximum penalty.

Defence barrister Steven Whybrow acknowledged Cole had "violently and viciously" murdered Mr Hollingshed in his home but said the offence was mid-range seriousness. He said there had been no previous history of violence between the pair.

The court heard Cole had a "very unfortunate upbringing" and started using drugs and drinking alcohol when he ran away from his broken childhood home at 15.

Mr Whybrow said Cole had been diagnosed with mental illness and his drug problems were unaddressed. He noted the offender had not taken part in treatment or programs in custody.

Ms Jones argued there were no prospects of rehabilitation and the offender posed a risk to the community if released.

Lawyers and the prosecution remain at odds over whether Cole had torn off Mr Hollingshed's screen door shortly before the killing.

Justice John Burns will sentence Cole next month.