Joyce Clarke, 29, was allegedly armed with a knife when the constable shot her on a street in Geraldton on September 17.

The officer faced Perth Magistrates Court on Thursday and had his identity suppressed due to safety concerns for his family, including children.

A short time later, he appeared in the WA Supreme Court and secured bail, which was not opposed by the Director of Public Prosecutions.

Justice Michael Corboy agreed there were exceptional circumstances.

The bail terms include a $100,000 personal undertaking, a $100,000 surety, surrendering his passport, staying away from WA departure points and not communicating with witnesses.

The man has been stood down on full pay and remains an officer.

Police Commissioner Chris Dawson was asked why it took months to charge the officer, replying: "This required a very thorough investigation."

Mr Dawson told reporters there were about 80 witnesses and CCTV vision from a house on the street.

Mr Dawson said support was being provided to everyone involved in the case.

"The circumstances of what occurred in Geraldton are tragic and will have a long-term impact on the lives of many people," he said.

"They include Ms Clarke's family, the Geraldton and wider community, and police officers right across our vast state.

"Today's event is rare and it is unusual in the history of WA policing."

Mr Dawson said the last time he spoke to the officer was about one month after the shooting because he had a duty of care.

Asked whether today was the worst day of his long policing career, Mr Dawson replied: "It's one of the saddest."

WA Police Union president Harry Arnott said the union was standing by the man.

"Our focus is on the member's welfare and ensuring his rights are protected."

Ms Clarke, a mother of one, had mental health problems and was recently released from prison when shot.

Family and supporters have demanded to know why lethal force was used, and rallies were held last year as racial tensions flared.

Ms Clarke's adoptive mother Anne Jones, who took care of her from the age of five months, said she was cautious about interfering with the legal process.

"I'm glad that steps have been taken to bring justice for Joyce," she said.

"The whole Aboriginal community will watch this process with great interest."

Her lawyer George Newhouse, from the National Justice Project, said Ms Jones had conducted herself with dignity throughout the long and traumatic process.

"All she can do now is hope that there is a just outcome for her and her daughter."

National Suicide Prevention and Trauma Recovery Project coordinator Gerry Georgatos said the group had been supporting 31 family members since Ms Joyce's "harrowed, tragic death".

The last time police were charged over a custodial death was in 1983 when five officers were acquitted of the unlawful killing of 16-year-old Aboriginal boy John Pat in Roebourne.

The royal commission into Aboriginal deaths in custody began a few years later.

Following Ms Clarke's death, the WA Police Force fast-tracked the rollout of body-worn cameras for officers in the area.

The officer will face Stirling Gardens Magistrates Court on March 25.

Australian Associated Press