A former Perth charity founder has walked free from the District Court after a jury took just 10 minutes to find her not guilty of stealing $120,000 from her late mother, who had Alzheimer's disease.

Key facts: Siham Carollisen said her dying mother told her to spend her money however she needed

Siham Carollisen said her dying mother told her to spend her money however she needed Carollisen defended herself on the Facebook page of her charity for the homeless

Carollisen defended herself on the Facebook page of her charity for the homeless The charges were laid following a Public Trustee investigation

Siham Carollisen cried when the verdict was read out, with her many supporters in the public gallery also visibly relieved.

Ms Carollisen, 33, had told the trial that her mother, Amina Carollisen, had given her permission in 2012 to spend $275,000 — including the $120,000 she was accused of stealing — which she received from the sale of the family home after her parents' divorce.

Her mother, whose condition progressively deteriorated from 2010 until she died in 2016, gave this undertaking not long before she moved in to live with Ms Carollisen and her family.

Ms Carollisen's explanation to the court echoed a earlier plea of support she posted on the Facebook page of her Perth-based Brothers and Sisters charity.

The charity, which she ran with her brother Mirwan, provided food, bedding and services for the homeless.

In the post from February 2017, soon after she was charged, Ms Carollisen said that during a traumatic time, she had followed her mother's instructions and maintained "the roof over our heads and kept going".

A photo posted on social media of of Siham Carollisen (r) and her mother. ( Facebook: Siham Carollisen )

It began when her former husband, the family's sole breadwinner, was involved in a devastating motorcycle accident in February 2014.

"As you could imagine, it turned my life upside down," she wrote in the Facebook post.

"With a husband on life support, 5 months pregnant, an 18-month-old daughter and a mum at home with advancing Alzheimer's, my situation was about as dire as it gets."

Mother gave permission to spend money

The trial was seen as a case study of alleged elder financial abuse, which rarely attracts criminal charges.

The charges against Ms Carollisen resulted from a Public Trustee investigation that commenced soon after it became the manager of Amina's finances.

As the case guardian for the Family Court settlement between her parents, Ms Carollisen was responsible for managing her mother's divorce settlement on her behalf.

The prosecution had argued that Ms Carollisen did not manage this money in her mother's best interests, instead spending much of it on jewellery, a car and fine dining for herself.

But defence lawyer Mark Trowell said her mother had given her permission to spend the money however she needed on many occasions, including saying "what's mine is yours" and making her daughter a signatory on her bank account.

Siham Carollisen said she regrets the agreement she had with her mother was not documented. ( ABC News: Rebecca Turner )

Ms Carollisen said in the Facebook post that she regretted not getting her mother's permission in writing.

"Why would I?" she wrote to the charity's Facebook followers.

"This was my mum. I did not hold expectation of any support."

She originally faced 10 counts of stealing a total of $140,000 but during the trial this was changed to just one charge of stealing $120,000.