The former NSW detective who led the investigation into the disappearance of William Tyrrell has been charged with misconduct offences.

Gary Jubelin quit the police force last month over allegations he used his mobile phone to record someone without a warrant and staff management complaints.

The 57-year-old, who also worked on the Bowraville murders and the disappearance of Matthew Leveson, strongly denies the allegations.

He will face four charges related to alleged breaches of the Surveillance Devices Act, which his supporters have labelled a witch hunt.

NSW Police said following a “number of complaints”, the professional standards command last year commenced an investigation into Mr Jubelin’s conduct during operational duties.

“Those inquiries disclosed a number of recordings allegedly made at locations in Parramatta and Kendall in New South Wales,” a police statement said.

William Tyrrell was playing in the backyard of his grandmother’s home when he went missing.

Kendall is the town on the NSW mid-north coast where William Tyrrell was last seen, playing in his grandmother’s front yard.

Before quitting, the former detective had been confined to desk duties while the professional standards probe took place.

Victim support groups across the country were shocked by the news of his departure.

Mr Jubelin has previously been praised by the families of the three children murdered in Bowraville as well as the parents of Mr Leveson whose remains were found in 2017.

The detective was chosen to re-investigate the Bowraville murders and gathered fresh evidence which led to a second trial.

Mr Leveson’s parents said they would still be looking for their son, whose body was found by police in the Royal National Park, if it were not for the work of the former detective.

Mr Jubelin is due to appear at the Downing Centre Local Court on July 30.

-ABC