Queensland mother Anne Maree Lee has been sentenced to nine years in jail after pleading guilty on Wednesday to child cruelty and the manslaughter of her toddler Mason Jet Lee.

However the 29-year-old will be eligible for parole in July this year, given time already served.

Lee sobbed when she was arraigned in the Supreme Court in Brisbane this morning, with her lawyer saying she had profound guilt and grief over the death of the 22-month-old.

Mason died in June 2016, days after being punched in the abdomen by his stepfather and Lee’s then-partner William Andrew O’Sullivan.

Anne Maree Lee said she had wanted to leave the relationship with O’Sullivan.

Crown prosecutor Michael Byrne said that while O’Sullivan inflicted the fatal blow at his Caboolture home, north of Brisbane, Lee did not take her son to a doctor.

Mason would have been in severe pain before his death, suffering from multiple injuries, including a perforated bowel, the court heard.

Mr Byrne described the last days of Mason’s life as a “wretched existence”.

“He was vulnerable and defenceless and the one person he was entitled to receive shelter [from] … not only failed to do that, but in reality contributed [to it],” he said.

“This is not a momentary or short-term failure to act, or a single decision not do something in the best interests of the child.

“Had medical treatment been provided the condition was survivable.

“It would have been obvious to any person that he was very sick and in urgent need of medical attention.”

Defence counsel Tim Ryan told the court his client had a “profound sense of grief and guilt” for failing to protect her son.

“Regardless of the sentence, she will have to live with that fact for the rest of her life,” Mr Ryan said.

He said Lee was not aware of the life-threatening injuries inflicted by O’Sullivan, who has already been sentenced to nine years in jail, but agreed she neglected to get help for the toddler.

Traces of drugs found in Mason

William Andrew O’Sullivan is serving a nine-year sentence over Mason’s death. Photo: ABC News

The court heard an autopsy revealed Mason had traces of methylamphetamine in his system, but there was no suggestion he was given the drug on purpose by either Lee or O’Sullivan.

Mr Byrne said it is most likely Mason touched a surface the drug had been on.

Lee knew that O’Sullivan was prone to “extreme anger” when he used ice but still left her son in her former partner’s care, the court heard.

She had met with a representative from the Department of Child Safety the week Mason died but never mentioned any concerns for her son.

“She wanted a plan to get out of the relationship,” Mr Byrne said.

“[Lee] explained O’Sullivan was extremely violent when he used ice.”

Mason had been hospitalised with injuries the same year he died. Photo: ABC TV News

The court heard earlier in the year that Mason died, he was taken to hospital with serious unexplained injuries.

“At the time of his admission to hospital the pain was said to be so severe it required a narcotic infusion,” Mr Byrne said.

“He had … mouth ulcers and infected skin lesions — more commonly found in children who receive a low standard of care.”

A third person, Ryan Robert Barry Hodson, who also lived at the home where Mason died, was also charged with the toddler’s manslaughter, but the charges were dropped.

–ABC