Deputy Police Commissioner Steve Gollschewski says he doesn't know what more Ms Langham could have done to protect herself, but has vowed to unearth any police failings.

Fearing for her safety, the 49-year-old grandmother had moved into a gated community at Logan, south of Brisbane. She made sure it had good security including 24-hour cameras.

On February 9, she took out a temporary protection order against ex-partner Gary Hely.

Neighbours have told The Courier-Mail that Ms Langham went to police "daily" with security footage and told them of four occasions when Mr Hely had breached that order in the space of a week.

About 9pm on Sunday, she made her final request for help - a triple-zero call to report a disturbance outside her townhouse.

The operator who took that call gave it a Code 3 ranking, a situation requiring police attendance but short of a Code 1 or 2 involving a threat to life or risk of imminent harm.

Police did go to Ms Langham's home, but not until after midnight. They could not determine if Ms Langham was there and left.

By 4am on Monday they were back, when the property was engulfed in flames in a fire police believe was deliberately lit.

Mr Gollschewski must now determine if police failed Ms Langham in any way.

He will delve into what Queensland police, interstate police and any other agency in Australia knew about Ms Langham and Mr Hely before they died, and whether that information was adequately shared.

He says it appears the operator who took Ms Langham's final call acted appropriately.

"Based on the information provided to that call-taker, they responded as we would expect. That doesn't mean the outcome, at the end of the day, was defendable by any means," Mr Gollschewski told reporters on Wednesday

He says no stone must be left unturned to identify any systemic failures.

"What other information was available, what other information was in our system and, indeed, in any other systems across the nation that may have assisted us to make other decisions on that night?" he said.

"Despite what we've learned and seen in other instances such as Tara Brown and Hannah Clarke and her children, here we are again. A person who is a victim of violence has needed to be protected, and we have not been able to protect her.

"We are not satisfied with that, and we will be relentless in trying to find out what has happened."

When asked what else Ms Langham might have done to protect herself, Mr Gollschewski said: "I don't know what more Doreen could have done."

Police are yet to formally identify the bodies found inside the blackened Browns Plains home. Autopsy results are still pending.

The police review and a separate coronial investigation are being overseen by the Crime and Misconduct Commission.

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Australian Associated Press