Man, 75, admits killing cyclist in WA

A 75-year-old man has admitted killing a cyclist with his car near Perth but claims he doesn't remember the incident because of a medical condition.

Keith Michael Osman was driving to a library on Old Coast Road in Mandurah on March 29, 2016 when he hit 70-year-old Gabriele Schiller-Brett and dragged her and the bike under his car.

Four witnesses saw his silver Ford Fairmont station wagon strike her and mount the kerb before re-entering the road and keep on going without slowing.

Paramedics rushed Ms Schiller-Brett to hospital in Mandurah but she died.

However Osman is pleading not guilty in the WA District Court to dangerous driving causing death, failing to stop and help and failing to report the crash to police.

His lawyer Sam Vandongen said in his opening statement at Osman's trial his client was telling "God's honest truth" when he told police "he was not aware of the occurrence of the incident".

He admits to driving the car when it hit and killed Ms Schiller-Brett.

He described the driver as being in an automatic state where his "mind was not connected to his body" and he was not doing "a willed act" due to a hypoglycaemic attack brought on by type-two diabetes.

His sleep apnoea might also have contributed, Mr Vandongen told the jury.

Police tracked him down through witnesses and CCTV footage, prosecutor Les Hobson said.

When police inspected Osman's car at his Erskine home it had damage consistent with hitting Ms Schiller-Brett. Biological evidence of the victim was also found on the vehicle.

The WA goverment has since introduced laws requiring motorists to leave at least a one-metre gap when passing cyclists and at least 1.5 metres when travelling faster than 60km/h.