Man remains under police guard after Perth woman allegedly stabbed to death in front of young daughters

A man remains under police guard after a Perth mother was allegedly stabbed in front of her two children.

Emmerick Lasakar, 35, died in Royal Perth Hospital on Monday after being found with serious injuries at her home on Knutsford Avenue in Kewdale.

Her partner of 15 years, Steven Dean, remains in hospital after he was arrested at St James the same night after a high-speed crash.

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Police Commissioner Col Blanch said today that Lasakar's two young daughters called triple zero.

"You can only imagine the horror that was encountered by them but also all the emergency services shortly after," Blanch said.

Dean is yet to be formally interviewed by homicide detectives.

"When we interview people we have to make sure that they are fully fit before we can do so," Blanch said.

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Police allege Dean, who has not been charged, fled the scene in his grey Ford Ranger Raptor dual-cab utility, holding up a service station in East Victoria Park before crashing into a tree at St James.

He was arrested in the backyard of a nearby home.

"He was taken to hospital by St John Ambulance where he remains under police guard," WA Police said.

Flowers were left at the home as forensic officers returned to the home to investigate on Wednesday.

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If you or someone you know is impacted by sexual assault, domestic or family violence, call 1800RESPECT on 1800 737 732 or visit 1800RESPECT.org.au.

In an emergency, call 000.