A 13-year-old girl's father is among eight WA men charged with 503 child abuse offences against her.

And the police officer in charge of her rescue said that it emphasised how their work exposed them to the dark, evil side of human nature.

Detective Superintendent Glenn Feeney outlines the charges to reporters. Credit:Ray Sparvell

Detective Superintendent Glenn Feeney told a press conference in Perth on Wednesday the alleged offences were committed when the girl was aged between 11-13 years.

The chief of the Sex Crimes Division said the girl's rescue followed a tip-off from a member of the public in April.