Police are hunting a man after he and a woman allegedly abandoned a two-year-old child in Mandurah to evade police.
Officer followed Edward Walley, 34, and Anain Victoria Whitehead, 30, after they spotted the pair riding a bicycle on Forrest Street on Wednesday with a child.
When Mr Walley and Ms Whitehead spotted the police, the pair bolted, with police alleging they left the two-year-old boy behind.
Ms Whitehead, was taken into custody a short time later.
The man, however, is still on the run.
Police will not release details of the relationship between the adults and the child.
Arrangements are being made for the boy's ongoing care.
Members of the public are advised not to approach Edward Walley.
Anyone with information should call police on 131 444.