William Anthony Rogers' Tuesday night cab shift was winding down after he spent hours picking up and dropping off weary passengers across Sydney suburbs.

But two hours before he was due to finish — in the early hours of October 4, 1988 — he activated the safety button on his taxi radio, alerting police to a potential problem.

When officers arrived, they found the 36-year-old motionless in the driver's seat, slumped over with a fatal bullet wound in his chest.

His cab had rolled backward into a fence at Ashfield, in Sydney's inner west, with the engine and the parking brake off and the car in first gear.

The window was wound down and the taxi sign was off, indicating to police that the cab was engaged at the time of the shooting.

The pay meter showed a fare of AU$10.70 (NZ$11.80).

More than 30 years later, no one has been charged in relation to the death and today NSW Police announced a AU$500,000 (NZ$550,981) reward for information that could help them solve the cold case.

A 1991 coronial inquest found the death was a result of a gunshot wound inflicted by an unidentified person or people.

While waiting for police, witnesses described seeing a man shake and kick the driver before running away.

He was described as being aged in his 20s, between 1.8m-1.85m tall, of slim build, with dark collar-length hair, and wearing light-coloured jeans, a matching jacket and a western-style long-sleeve shirt.

NSW Police's Unsolved Homicide Squad began re-investigating the death in March 2023.