A coronial inquest is examining why nothing was done to contact a Perth woman whose stepson had repeatedly threatened to kill her in the weeks before he fatally attacked her with a knife.

Sally Kaur, 57, was murdered by her then 19-year-old stepson Catalin Borbil at the family's Koondoola home in December 2013.

Borbil was under the influence of methylamphetamine and had demanded money before repeatedly stabbing Ms Kaur as she chopped vegetables in the kitchen.

Ms Kaur had 15 stab wounds in the chest, abdomen, left arm and neck.

An inquest has been told Borbil was living at the house, after being released from custody on bail about two weeks earlier, on charges of stealing a car and possessing a controlled weapon.

Chaplain, prisoner heard threats

Kate Ellson, counsel assisting the coroner, said that while in prison Borbil had made threats against his stepmother to a chaplain and another prisoner.

The threats included him saying:

"I hate her, and if I can get a gun I will put it to her head."

He also intended to kill his stepmother "put her in a trunk and then eat her", the inquest heard.

One of the threats was passed on to police the same day Borbil appeared in court and was granted bail, but the prosecuting officer was not made aware of it and Borbil was released to live in the same house as Ms Kaur.

Further details of Borbil's threats were made available to prison authorities in the days following, but the information was not approved for release to police until five days after Ms Kaur was murdered.

Ms Ellson said the inquest would examine why no-one contacted Ms Kaur either directly or indirectly about her stepson's threats, and whether anything could have been done to prevent her death.

The inquest heard there had been instances of domestic violence involving Ms Kaur reported to police from time to time, but they had not involved her stepson.

She had however been assigned a domestic violence advocate in 2012, and the inquest is also examining whether that advocate ever received information regarding her stepson's threats.

Catalin Borbil pleaded guilty to murdering Ms Kaur and last year was sentenced to life with a 17-year minimum.