Anna Horneshaw did not receive a diagnosis until after she went to prison, and it pains her mother deeply.

Key points: Carers say they feel like they are not being taken seriously by the health system

Carers say they feel like they are not being taken seriously by the health system One man told the inquiry he was afraid to seek help, worried authorities would put him and his brother into care

One man told the inquiry he was afraid to seek help, worried authorities would put him and his brother into care A woman says she panicked when her mentally unwell brother was released from care without her knowledge

"On the day that I heard what Anna had done, I felt like screaming," her mother Mary Pershall told the Royal Commission into Victoria's Mental Health System on Friday.

Anna is serving 17 years in prison. In 2015, aged 28 and pregnant, she stabbed her 67-year-old roommate to death.

"For so long we expected a call to say she was dead, instead we got a call to say she'd killed someone else," Ms Pershall told the commission, fighting back tears.

For years, Ms Pershall, her husband John and their daughter, Anna's sister Katie Horneshaw, had sought help for Anna's increasingly erratic behaviour.

A mental health facility refused to admit her after discovering drugs. A rehab centre said she could not be treated because of her mental health issues.

In prison, Anna's mother and sister say she is improving. She has a plan, and a diagnosis — schizoaffective disorder with borderline traits.

"Society might say, someone like our daughter, she's a mentally-ill person addicted to substances, we can just throw her under the bus," Ms Pershall said.

"But it's never just that person that's suffering."

Katie Horneshaw, who now cares for her imprisoned sister's child, agreed.

"What happens is the people trying to care for that person, like my mum and dad, and me, they end up completely exhausted and traumatised and at the end of their rope," she said.

"That's what we're seeing today."

Jesse Morgan (right) with brother Alex and their mother. ( ABC News: James Bennett )

Carers tell stories of loved ones lost, opportunities foregone

"We lived in constant fear of being separated," 25-year-old Jesse Morgan told the commission.

Mr Morgan was 14 when he began looking after his mentally unwell mother, and caring for his 8-year-old brother Alex.

"She had agoraphobia, which meant she stayed in her room."

As an adolescent, he dropped out of Year 12 and worked six days a week at a pizza shop to make enough money for the family to survive.

He told the inquiry that he was afraid to seek help, worried that authorities would put him and his brother into care if they discovered what was happening.

"[The fear was] if they came and knew the extent of how we were living and the issues that were going on in the household, then my brother and myself and my mum would all be separated and taken into different foster care situations," he said.

Another carer, Rebecca Thomas, told of her panic upon learning a plan to transfer her mentally unwell brother to community care had been abandoned without her knowledge.

"This is not going to end well," she said she told a doctor.

Several days later, he committed suicide.

'System not working for anyone'

Those who gave evidence on Friday said the family and friends of those battling mental health issues should be taken seriously.

"Rather than being treated as an asset who knew Anna better than anybody, we were treated as an annoyance," Ms Pershall said.

Ms Thomas said pressure was put on carers.

"The system can't do it, they expect us to do it, but yet they give us so little information," she said.

Ms Pershall said families were relying on the royal commission and the State Government for change.

"At the moment it is just such a difficult system to navigate and it doesn't seem to be working for anyone," she said.