An accused murderer claims his ex-girlfriend hit her head on the floor and died after one of their arguments became physical.

Lachlan Young’s barrister made the allegation as he questioned witness Benjamin O’Keefe over his involvement in Hannah McGuire’s death.

O’Keefe told the Victorian Supreme Court he saw Young set fire to a Mitsubishi Triton early on April 5, 2024, and later learnt McGuire’s body was inside.

But barrister Glenn Casement claimed O’Keefe knew McGuire was in the ute because Young told him she was dead.

The lawyer said Young called O’Keefe at 2.53am on April 5 to say “something had happened”.

When O’Keefe allegedly arrived at the Sebastopol home in regional Victoria, Young explained he had forcibly pushed McGuire during an argument.

McGuire was thrown to the ground and died after she hit her head on the bathroom floor, Casement claimed.

Young has admitted he killed McGuire but denied he murdered her, instead offering to plead guilty to manslaughter.

That offer was rejected by prosecutors at the start of his murder trial.

Casement claimed O’Keefe saw McGuire on the floor and devised a plan with Young to move her body to Scarsdale.

The lawyer alleged the pair drove in convoy to the remote bushland and, when they arrived, O’Keefe was the one to set fire to the Triton using his own blowtorch.

Casement claimed O’Keefe then lied about his involvement to avoid being charged as an accessory to murder.

O’Keefe was arrested and questioned over McGuire’s death, but he was never charged.

He denied all of the defence allegations, repeatedly saying he never went to Young’s home and did not know McGuire’s body was in the ute.

O’Keefe also rejected the claim he was the one to start the fire, maintaining he stayed in his own car as Young lit the blaze.

He told the jury he had been truthful to police and did not lie about Young’s plan to drug McGuire.

He claimed Young told him on April 2 that he would ‘roofie’ McGuire and fabricate a crash with her in a car, so he could scare her out of taking their house.

O’Keefe admitted he did go with Young to the Scarsdale bushland and then deleted security camera footage from his home.

But he told the jury he wiped the recording because he did not want to be connected to the car fire.

He maintained he only suspected McGuire was in the vehicle after he learnt she had died later that morning.

O’Keefe said he visited Young after learning the news, worried he may have been implicated in a murder.

“I went up to him and said ‘Hannah better not have been in that car’,” he told the jury.

He claimed Young told him McGuire was already dead as she had been suffocated.

O’Keefe admitted he did not contact police, instead deciding to drink with Young and then go on a camping trip with friends.

He shared what had happened and his mates advised him to go to the police, but he instead returned home and watched a movie.

Detectives arrested O’Keefe on April 7 and questioned him for almost two hours over the murder of McGuire.

The jury was told O’Keefe learnt in November 2024 that he would not be facing any charges.

The trial before Justice James Elliott continues.

Help is available from the Men’s Referral Service on 1300 766 491.