A Corrective Services NSW spokesman said Sampieri died at 8.30pm yesterday (Sunday) in the secure annex at Prince of Wales Hospital. He was 57.

Sampieri had been receiving treatment for liver cancer. His sentencing hearing was told he had been given just a 60 per cent chance of surviving for five years.

Sampieri became the first person to be sentenced to life imprisonment without a non-parole period for sexually assaulting a child under 10 since the law was changed in 2015.

Before the change, the maximum sentence was 25 years.

During the November 2018 attack, which lasted 45-50 minutes, Sampieri punched his victim in the face, forced her to perform acts of depravity, bound her wrists and ankles and attached them to a cord around her neck and stuffed toilet paper in her mouth to silence her.

Sampieri, who was armed with a knife, told the girl he would cut her throat if she tried to alert anyone who came into the toilets.

Imposing sentence, Judge Paul Conlon said, "Throughout the whole ordeal, the offender demonstrated a callous disregard for this young child as he violently assaulted her and went about dominating and controlling her with the use of a knife and cords, and subjecting her to sexual abuse of the most horrifying and degrading type.

"I agree with the submission of the Crown that the taking of the victim in such circumstances and what happened to her during the course of the detention can only be described as every parent's worst nightmare."

Judge Conlon said there would be "lifelong consequences" for the victim to deal with "in respect of emotional and psychological scarring".

Sampieri pleaded guilty to 10 charges, including three counts of sexual intercourse with a child under 10, for each of which he was given a life sentence.

His offending came six years after Sampieri lured a 60-year-old woman into his Elliotts Road, Fairy Meadow unit and sexually assaulted her.

Court documents reveal the 2012 attack occurred as Sampieri was in the midst of a "sex binge", blitzing women whose photographs and contact details he had found in the newspaper with explicit phone calls.

One referee at the time told the court Sampieri was "sleepy, sedated and not motivated" when he used heroin, but radically different when he used ice. Sampieri described ice as "a sexual drug" and said it blurred the line "between what was acceptable and unacceptable"

After consulting a detailed phychiatrist's report, sentencing Judge Paul Conlan concluded Sampieri had "reasonable prospects of rehabilitiation" and handed down a maximum seven-year term. Sampieri spent less than five years behind bars before he was released on parole on September 7, 2017, 14 months before the Kogarah attack.