A man who fatally stabbed his mate at a Boxing Day barbecue at Mayfield was pushing his car down the street after it failed to start when police arrived, a court has been told.

Crown prosecutor Neil Adams SC told the Newcastle Supreme Court on Tuesday in a judge-alone trial how the victim, Steven O’Brien, 50, died after having his throat slashed, cutting the jugular vein.

The knife wound measured 22cm long and 4.4cm wide.

Shaun Garry Johnson, 38, of Coopernook, has pleaded not guilty to murdering Steven O’Brien in the Newcastle suburb on 26 December, 2019, but guilty to the lesser charge of manslaughter, claiming excessive self-defence.

Mr O’Brien and his family and friends had been celebrating Boxing Day in the backyard of his home when Johnson joined them later in the evening.

It was several hours later after Mr O’Brien’s parents had gone to bed when Mr O’Brien and Johnson began arguing while drinking outside with a third man.

Mr O’Brien grabbed Johnson by the shirt and told him to leave before Johnson stabbed him in the neck.

Mr Adams told the court a neighbour saw Johnson leave Mr O’Brien’s house and try unsuccessfully to start his car before saying, “I guess I’m staying here a bit longer now”.

The prosecutor said at one stage Johnson was sitting in his silver Toyota 4WD when a neighbour confronted him and Johnson lunged at him with a knife through the car window.

Another neighbour claimed she saw Johnson jump over her fence and heard the front tap running before he jumped over another fence.

Mr Adams said a black folding knife, which could have been the weapon used to stab Mr O’Brien, was found under a nearby bridge.

Johnson was later seen trying to push his car down the street to get it started when the first police car arrived at the scene.

An autopsy found the cause of Mr O’Brien’s death was one stab wound to the left side of his neck.

Mr Adams said tests on both the folding knife and a Swiss Army knife found in Johnson’s car revealed no DNA or blood but he could have used the garden hose to wash the weapon clean.

Leading Senior Constable Natasha Garcia told the court she arrived at the crime scene at about 2.30am to find “a significant blood trail” leading from the road back to Mr O’Brien’s house.

The trial before Justice Richard Cavanagh continues. 

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