A third man has been charged with the kidnapping and murder of a woman who was dumped outside a Perth hospital.

Ross James Boag, 19, was arrested earlier today at a house in Butler over the death of 27-year-old Peta Fairhead, three days after police appealed for him to come forward.

He has been charged with murder, three counts of kidnapping and three counts of armed robbery, and is due to appear in court tomorrow.

Ms Fairhead was pushed out of a car at the entrance of the Joondalup Health Campus just after 3:00am last Wednesday before the vehicle sped away.

She was rushed inside but pronounced dead a short time later.

Two other men have already been charged over Ms Fairhead's death.

Lucas James Yarran, aged 20, and Leroy Smith, 19, appeared briefly in Joondalup Magistrates Court on Friday.

The court was told the men stormed a home in the northern Perth suburb of Ridgewood in the early hours of Wednesday morning while armed with a machete and a baseball bat.

They are accused of kidnapping Ms Fairhead and two other people in the home, before stealing jewellery, mobile phones, a wallet and methamphetamine.

It is alleged they killed Ms Fairhead a short time later before dumping her body outside the hospital.

The men were not required to plead to seven offences including murder, kidnapping and armed robbery.

They were remanded in custody and are due to reappear in court later this month.