An Aboriginal woman in Perth is searching for her vulnerable son who has been missing since Sunday night.

Gwen Hansen told National Indigenous Times her son Joseph Hume, 33, has been missing since approximately 11pm on Sunday, but she was not told until 8.40am on Monday.

"Joseph lives with a disability and has communication difficulties. After approximately two years at Graylands Hospital, he was transitioning back into the community with multiple services involved in supporting his care, wellbeing and independence," she said.

"Despite all of those supports surrounding my son, I was not informed that Joseph was missing until approximately 8:40 am on Monday, almost ten hours later. Those hours mattered. I could have been searching for my son. I could have provided police with vital information about Joseph, where he might go, who he might contact and what could assist in finding him. Instead, I did not even know my son was missing."

WA Police have issued a public notice seeking help in finding Joseph. He was last seen in the vicinity of Brockway Road in Mount Claremont on Sunday night and is described as being 180cm tall, of solid build, with dark brown hair and a beard. They noted concerns were held for his welfare.

Anyone who has seen Joseph or has information about his whereabouts should call 131 444.

Ms Hansen told this publication she had been looking for Joseph since Monday morning.

"I have been driving around, into the city, since I found out on Monday. I could have done that Sunday night and found him, because I have done that before in the past," she said.

"This is the longest he has been away."

Ms Hansen said she has been trying to establish exactly what happened, and is "still without a clear and accurate account".

"I have asked Joseph's NDIS provider for a written report detailing what occurred that night, including who was supporting him, when he was last seen and what happened surrounding his disappearance. I am still waiting for that report."

She said she had spoken with Joseph's guardian, and said "responsibility was being directed towards the NDIS provider rather than being given the clear answers I desperately needed".

"I don't want services pointing fingers at each other. I want facts," Ms Hansen said.

"I want to know what happened immediately before Joseph disappeared, who was supporting him, when his absence was discovered, what action was taken, when police were notified, what each service knew and when they knew it, and why I was not contacted immediately.

"I also need to know whether something happened before Joseph disappeared that caused him distress or contributed to him leaving."

Ms Hansen said this is not the first time she has raised serious concerns about her son's care.

"Concerns have previously been formally raised, and relevant services and individuals have already been put on notice about those concerns," she said.

"Now my son is missing, and I am still fighting to get accurate information."

She told this publication "we work 24/7, this is a parent's duty" and was frustrated she was not told sooner that Joseph was missing.

"When a vulnerable person living with a disability has multiple services involved in their life, accountability cannot disappear between those services," she said.

"I am not making conclusions about who is legally responsible. I am asking for something very simple, tell me what happened to my son.

"Joseph is not a hospital file, an NDIS number or a case being managed by different agencies, he is my son, he is an Aboriginal man living with a disability, he is vulnerable, he is loved, and his life matters."

Ms Hansen said her immediate priority is finding Joseph alive and safe, but she also needs transparency about what happened and "whether the systems responsible for supporting my son did what they were supposed to do".

National Indigenous Times has contacted the WA Health Department for comment.

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