Benjamin James McCasker, 31, pleaded guilty to unlawful striking causing death over an October 2020 incident at Caboolture shopping centre, north of Brisbane.

McCasker had consumed a significant amount of alcohol before the attack, and was upset at having to wait about an hour for his partner’s nail appointment, the Supreme Court was told on Friday.

When asked to get his partner a drink as they sat at a coffee shop, he responded by smashing a wooden chair on the ground, Justice Peter Davis said during the sentencing hearing.

This prompted 38-year-old security guard Charles Lewis to make his approach, which he did so slowly and with his hands in his pockets, Justice Davis said.

CCTV footage played before the court captured McCasker punch Mr Lewis to the side of the head after minimal interaction.

The vision shows the security guard lying motionless on the ground as onlookers gather and McCasker flees the scene.

In discussions about whether there was evidence the punch caused Lewis to fall unconscious,

Justice Davis said that it seemed as if “he just goes down like a sack of potatoes” without using his hands to brace for the fall.

“There’s no suggestion of him having the opportunity to cushion his blow … he just goes down,” he said

Lewis was left on life support for “some time”, including his brother’s wedding, before dying of brain injuries, the court was told.

McCasker did not hand himself in and was picked up by police only after his brother intervened, Justice Davis said.

He initially told officers Lewis said something adverse to his partner, shoved him and asked him if he wanted to fight.

“You sought to defect blame from yourself onto the person who you had killed,” Justice Davis said.

“He didn’t threaten you at all, you just attacked him in a rage.”

McCasker was sentenced to 13 years in jail with 331 days declared as time served.

He must serve at least 80 per cent of his sentence before being eligible for parole.