'You Let A Murderer Walk Free' Says Distraught Brother Of Cheryl Grimmer

The trial of a man accused of murdering Cheryl Grimmer almost 50 years ago will not go ahead after the court found key evidence was inadmissible.

The man, who cannot be named as he was underage at the time of the 3 year-old's disappearance, pleaded not guilty to her murder in September 2018.

A trial was scheduled in May.

But today his charges were sensationally dropped after the court found an interview with the accused 18 months after her disappearance was inadmissible.

"In the absence of that interview there was insufficient evidence for the case to proceed," the Director of Public Prosecutions said in a statement.

The accused confessed to the murder in 1971 when he was just 17 years of age. He'd also had a history of mental illness.

Regardless, the investigating police at the time conducted the interview without a parent or proper support person and obtained the confession, according to Justice Robert Allan Hulme, "unfairly".

Therefore, the evidence could not be used in the upcoming trial and the Crown accepted that the case could not succeed without it.

The 65-year-old accused was allowed to walk free. "A murderer walks free because of a technicality because of a police mistake," Ricki Grimmer, Cheryl's eldest brother, told 10 News First exclusively outside Darlinghurst Court.

"You let a 3-year-old murderer go free twice. He walked in gives you a full confession and you let him walk away.

"I don't know how this can happen someone's got to be accountable for this, there's got to be answers, we deserve answers... why the mistakes were made."

10 News First contacted the New South Wales Police, it said it is assessing its options following the court's decision.

Cheryl was abducted from a toilet block while on a family beach trip in Fairy Meadow, near Wollongong, in 1970.

Extensive searches at the time turned up nothing and several coronial inquests found she'd been murdered.

Ricki Grimmer and his family believed their decades-long nightmare might soon be over. Image: 10 News First

Worse, her parents Vince and Carole, died without knowing what happened to her.

But a breakthrough in 2017 buoyed the hopes of her brothers Ricki, Paul and Stephen.

NSW Police extradited a Melbourne man and charged him with murder.

He's spent nearly two years behind bars, maintaining his innocence.

At the time, the Grimmer family had hoped their decades-long nightmare was over.

"How's the last 50 years; weeks turn into months, turn into years, they give us all this false hope," Ricki added, as he reflected on what this decision meant.

"I'm at a loss how people can keep making mistakes with peoples’ lives. This is my family."