Friend-killer wishes he could take it back

Wayne Kevin Beattie wishes he could go back to the day he killed his friend and undo it.

He and Grant Shannon had been mates for more than 30 years, living together on and off since they met in high school.

But after an argument in February 2018, Beattie lashed out at his childhood friend with a knife in the Melbourne home they shared.

The blade punctured an artery, killing Mr Shannon.

Beattie, who pleaded guilty to manslaughter and was sentenced on Friday, will serve up to six-and-a-half years behind bars.

Supreme Court Justice Lex Lasry said Beattie was genuinely remorseful, revealing the 50-year-old had written a "thoughtful and emotional" letter to Mr Shannon's family and friends.

He reflected on their lives and friendship and wished what happened that night had never occurred.

Beattie, believing that his partner would be returning home from hospital in the coming weeks, had asked Mr Shannon to move out of his house.

Witnesses said Mr Shannon was visibly upset at being asked to leave.

There's no witnesses to Mr Shannon's death, but neighbours heard two men yelling and swearing.

Beattie told police Mr Shannon had yelled for him to come out of his bedroom and banged on the door.

He held the door shut and told his friend to shut up.

Beattie grabbed a knife from his bedside table - kept there in case of intruders - and opened the door.

He thrust the knife at Mr Shannon, hitting his hand.

Justice Lasry said the man claimed he was just trying to get Mr Shannon away from him when he lashed out again toward his friend's chest, hitting him in the groin.

Mr Shannon's devastated parents said the "unrelenting pain" of knowing their son's friend had killed him had shattered their lives.

"Grant always gave without question and that's what made him so loveable," his sister Kylie McColl said.

"(He was) betrayed so completely by a friend."

Justice Lasry said though dangerous, Beattie's actions were spontaneous and he'd made no attempt to conceal what he'd done.

He tried twice to call triple zero and when calls wouldn't connect he called a friend.

The judge said the consequences of Beattie's actions were both tragic and futile.

Beattie has already served two years behind bars before being sentenced and must serve another two before he becomes eligible for parole.