When an acquaintance suggested robbing a friend of his prized BMW to sell it for drug money, Christopher McEachran volunteered to help.
He even offered to bring a "toy" to guarantee the armed robbery would be successful.
Michael Mammone was lured to a primary school in Cranbourne where McEachran and a woman, who cannot be identified, were waiting for him.
The 2008 model BMW was Mr Mammone's pride and joy - he never let anyone else drive it.
So when McEachran demanded his keys on June 26, 2020 he refused to hand them over.
There was a scuffle and the woman, who later went to police to confess her part in the set-up, said she heard Mr Mammone being hit across the legs with a large knife or stick. His hands were then cable-tied together.
Before they fled the scene, leaving Mr Mammone's body on the ground, the woman asked if he was dead.
"No, he'll be alright," McEachran told her.
Mr Mammone's body was discovered near the school the following morning.
McEachran faced a pre-sentence hearing in Victoria's Supreme Court on Monday after pleading guilty to armed robbery and manslaughter.
Pathologists found Mr Mammone suffered lacerations and bruises consistent with an assault.
He had a potentially lethal amount of methamphetamine in his system as well as cannabis.
In combination the two drugs can cause arhythmia, which the pathologist identified as a possible cause of his death.
He also had natural disease of the heart.
McEachran wasn't aware of the drugs or the underlying heart disease, which reduced his moral culpability for the crime, his barrister Sam Norton said.
McEachran and the woman planned the robbery earlier in the evening after discussing ways to get money for drugs.
When the woman questioned what would happen if he didn't hand the car over, McEachran replied "he will because I'll scare him".
He told her he'd bring a "toy" which prosecutors said was a weapon.
Mr Norton said his client's history was a sad one and while he had a significant history of violence there had been a thinning out of offending as he got older.
He'll be sentenced at a later date.