A judge has ripped into the “extraordinary cruelty” of a woman who blackmailed the Melbourne parents of a dying baby girl.

Siti Kamal saw an opportunity in distraught dad Jay Windross’ social media plea for the return of his wife Dee’s phone, filled with pictures of their terminally ill 11-month-old, Amiyah.

As the baby drew her last breaths, Kamal sent Mr Windross more than 90 messages demanding $1000 in return for the phone.

Despite never having the device, the 24-year-old threatened to sell it or delete the pictures of Amiyah.

Kamal exchanged nearly 160 messages with Mr Windross in 24 hours, including after Amiyah’s death from an undiagnosed neurological condition.

County Court of Victoria Judge Elizabeth Gaynor berated Kamal for her “extraordinary cruelty” in the face of “indescribable anguish”.

“You’ve got a couple spending their last days with their dying child,” the judge told Kamal during a plea hearing on Monday.

“In a situation of almost indescribable anguish … I can hardly think of a worse case [of blackmail].

“The extraordinary cruelty that this involved is a concern.”

Siti Kamal’s crime was “morally indefensible”, her lawyer told the judge. Photo: Facebook

Kamal, aged 24 at the time, has pleaded guilty to blackmail and spent nearly 10 months in pre-sentence detention.

Her barrister Rahmin De Krester acknowledged the woman would be handed a jail sentence but asked that be time already served in custody.

“I accept that this is a morally indefensible crime,” Mr De Krester said.

He asked Judge Gaynor to take into account Kamal’s age, lack of criminal history, early guilty plea and problems with impulsivity.

She does not have a diagnosable disability or personality condition and the judge indicated she was preparing to hand down a longer jail sentence.

“The only conclusion the court is left with is this was a deliberate, albeit impulsive, decision to act in an extraordinarily cruel way,” Judge Gaynor said.

“These victims were chosen because of their vulnerability.

“To see an opportunity in the suffering of others is extraordinarily concerning.”

Kamal will be sentenced on March 10. She is likely to be deported to Malaysia after her release from jail.

-AAP