"He's ruined a child's life, and he just gets away with it."

WARNING: Post contains graphic images of an injured infant.

Coby Walther was just six months old when his babysitter almost killed him, leaving him with serious brain damage and a life-long disability instead.

The little boy from Ambarvale, NSW was in the care of his aunt Jessica Miles and her boyfriend Adam Boardman one night in May 2010 when he sustained the horrific injuries that profoundly impacted his and his family’s lives.

In a fit of rage, Boardman shook the baby – eventually admitting to the assault after police questioning.

Coby's mum Sian Regal is still pained by memories of walking in the next morning to find her son bruised and unresponsive.

"I walked in and Sean's sister was holding Coby in her arms, like, in front of her, limp... he couldn't breathe properly," she told Channel Nine's A Current Affair in an interview that aired on Wednesday.

Once in hospital, Sian didn't know if her son was going to survive.

"A nurse had told me that Coby was going to die. I just broke down... I couldn't fathom the thought of losing my son at all."

Coby did survive, but only with severe brain damage causing an intellectual disability. Coupled with his cerebral palsy, the little boy requires a high level of medical care.

As Sian put it, Boardman ruined his life.

"He's ruined a child's life. He's ruined a whole family's life and he just gets away with it," she told ACA.

Boardman was convicted of causing grievous bodily harm to Coby and sentenced to 10 years jail. However, Sian has learned he's about to be released on parole after serving six years behind bars.

"Six years is nothing. Six years. What's six years?" she said, adding he hasn't "done his time" for the crime.

"His time would be a lifetime because they don't understand what Coby goes through every day - every single day.

"Coby's got a life sentence."

Sian said she wanted to highlight how easily violent offenders like Boardman can go unrecognised once they're free.

The family started a GoFundMe page for Coby in 2014 - which is still active - to help with Coby's medical bills and associated costs. You can donate here.