Updated 12.58pm: The High Court in Hamilton has heard shocking details about the night a man an elderly man was bludgeoned to death in a central city public toilet.

Turei Kingi has today admitted murdering Jacques Donker and has been convicted.

Kingi, a man who often slept rough on the streets of Hamilton, showed no emotion as the harrowing summary of facts were read out.

The court has heard he'd spotted Mr Donker, a 76 year old man slight in stature, and told an associate he was going to kill him.

The victim was struck over the head with a full bottle of alcohol and his killer stole his car keys out of his hand as he lay unresponsive on the toilet floor.

The police summary of facts state Kingi had been consuming alcohol, cannabis and synthetic cannabis the night he killed Mr Donker.

So merciless was the attack that paramedics found the label of the bottle of whiskey used to kill him stuck to the side of the victim's face.

Crown Lawyer Ross Dowch says Kingi stole the victims car with the intention of selling it for $10,000.