Investigation into WA death in custody

West Australian police are conducting an internal investigation into the death of a 22-year-old woman in custody.

The woman was taken to South Hedland Police Station last Saturday and was due to be released from custody on Tuesday.

While in the lock-up, the woman complained of being unwell and was taken to the Hedland Health Campus on Saturday and Sunday.

Both times, medical staff provided police with a certificate saying the woman was fit to be held in custody.

On Monday, the woman again told police she was unwell and was taken to the Hedland Health Campus where she died.

The Internal Affairs Unit will investigate the death in police custody and will prepare a report for the coroner.