Vic murder lawyer lays out defence

Amber Wilson
AAP

A young Victorian man who sat filing the barrel off a gun while his friend viciously attacked his girlfriend is innocent of her murder, his lawyer has argued.

The trial of Wayne Marmo, 25, accused of murdering Simone Quinlan in August 2015 will continue on Friday as his defence lawyer completes his closing address to the jury.

Ms Quinlan was allegedly viciously attacked in a prolonged assault by her boyfriend Brendan Neil, in which she was punched, kicked, had her mouth taped up, and struck several times on the head with a hammer.

The court has previously heard Marmo then transported Ms Quinlan's body to Kangaroo Flat, near Bendigo, where he dumped her down a mineshaft and set her remains on fire.

Along the way, he shot her in the head at least five times.

Defence barrister Scott Johns argued on Thursday that Marmo was not "complicit" in Neil's assault because he couldn't have expected the violence to escalate as it did.

However, prosecution lawyer Kevin Doyle argued Marmo "indicated his approval" in the attack by sitting at the kitchen table while the assault occurred, filing the barrel off a gun, reversing the car to transport the body, and suggesting to Neil he needed to "get rid of her".

Mr Johns is expected to complete his closing address on Friday, after which the jury is expected to retire to consider its verdict.