Brendan James Smith, 39, was set to be released from prison after the Crown unusually conceded that its own case against him was not strong.

Smith was jailed after he was charged with digitally penetrating a five-year-old girl at a public toilet at Elephant Park in November 2016.

The NSW Supreme Court heard this week that the girl was at the park with her mother and sister when she asked to go the toilet.

The girl mistakenly entered the male bathroom and when she emerged told her mother: “the man touched me on the gina and it hurt.”

The girl's mother saw a man leave the toilet block and told a member of the public, who had just arrived at the park, what had happened and asked for help.

The bystander identified the man as Smith, as he walked away and from a distance of about 15 metres, she had gone to school with him but had not seen him since he was in his mid-teens more than 20 years ago.

Smith was arrested the following day and charged with having sexual intercourse with a child under the age of 10.

But the court heard that DNA swab samples taken from the girl after the alleged assault were not sent for forensic analysis until March this year.

Crown prosecutor Colin Shaw said the preliminary results showed no match with Smith's DNA.

Significantly, the court heard, no male DNA at all was located in a swab taken from the girl's genitals and the accused's DNA was able to be excluded from the inside of her underpants.

"I think in a nutshell while the DNA will not be determinative it is certainly not corroborative of the charge," Mr Shaw said.

The court also heard that the child had told different accounts of the alleged assault, including whether she had been touched inside her vagina.

Justice Geoffrey Bellew criticised the investigating police for waiting five months to have the DNA swabs analysed.

"There was no explanation whatsoever why this was so and its unsatisfactory nature needs no further comment," Justice Bellew said.

"This is not a complicated factual case. The evidence could hardly be described as voluminous ... much of the evidence was obtained on the very day almost eight months ago on which the offence is said to have been committed."

Justice Bellew said he would “go so far as to categorise the Crown's case as weak”.

While Smith has a lengthy criminal record dating back to his youth, Bellew noted there was "nothing whatsoever" in his history similar in nature to the current charge.

The conditions Justice Bellew imposed on Smith's release effectively amount to placing him under under house arrest.

Smith must live with his mother in Orange and can only leave his home in her company and for specifically approved purposes which include attending court, legal conferences and the police station.

Smith is next due to appear at Orange Local Court on Monday.

A committal hearing is due to take place which will determine whether there is enough evidence against him to proceed to trial.