The elderly driver who argued he was having a diabetic episode when he hit and killed a Mandurah cyclist has been cleared of causing her death.

Gabriele Schiller-Brett, 69, was riding her bicycle through a roundabout on Old Coast Road near Halls Head in March 2016 when she was fatally struck by the Ford Fairmont station wagon driven by then 73-year-old Keith Michael Osman.

Mr Osman faced a six-day District Court trial to defend charges of dangerous driving causing death, failing to render assistance and failing to report the incident to police, arguing he was not responsible.

Camera Icon Keith Michael Osman leaves the District Court today. Credit: Michael Wilson

He said that at the time of the collision, he was in the throes of a “severe hypoglycaemic episode”, brought on by his type-2 diabetes, meaning he was in an “automatic state” and had no recollection of the incident.

After deliberating for three hours today, a jury accepted his explanation and acquitted him of all three charges.

During the trial, the jury was told that after Ms Schiller-Brett hit the left side of the car and fell to the road, Mr Osman ran over her and the bike, dragging them both underneath his car and into the kerb.

Prosecutor Les Hobson, who submitted Mr Osman had failed to keep a proper lookout for Ms Schiller-Brett, said the elderly driver then steered back onto the road, slowed slightly and drove off.

CCTV vision showed his car driving into the Mandurah CBD and he was later spotted on camera at the library returning and then borrowing books.

Ms Schiller-Brett suffered catastrophic injuries to her legs, pelvis, abdomen and chest. She later died in hospital.

Police tracked down the car and Mr Osman. Testing on the car showed biological material from Ms Schiller-Brett was still present on the bottom of the vehicle.

In his closing address, defence lawyer Sam Vandongen said Mr Osman was a gentle man of “impeccable character” and would not have knowingly run over Ms Schiller-Brett and “cold-heartedly” left the scene.

Mr Vandongen said he had made no attempt to hide or wash the car and parked it at the library, which was next to the police station, which he said were actions “inconsistent with the idea of a callous man”.

“Something very wrong happened with his mind that day and hypoglycaemia is consistent with it,” he said.