Victims' families have labelled the case against a high-profile NSW homicide detective a "witch hunt", pledging their support for Gary Jubelin who is accused of using a mobile phone to record someone without a warrant.
Jubelin is expected to face a Sydney court in July after he was charged with four offences under the Surveillance Devices Act on Friday.
It comes after he tendered his resignation in May, having been taken off the William Tyrrell case while he was investigated over misconduct allegations.
It's understood the claims related to staff management and the recordings.
NSW Police on Friday said professional standards began investigating the 57-year-old's conduct in 2018 following a number of complaints.
"Those inquiries disclosed a number of recordings allegedly made at locations in Parramatta and Kendall in NSW," a police statement said.
Kendall, on the mid north coast, is where three-year-old William Tyrrell vanished in 2014.
A statement issued by Jubelin's lawyer Margaret Cunneen SC - a former state prosecutor - said it was understood the charges related to "recordings made during the execution of Inspector Jubelin's duties".
"Detective Inspector Jubelin denies any wrongdoing whatsoever and will strongly defend the charges against him," she said.
In addition to leading the fresh search for William, Jubelin was involved in investigating the death of Sydney man Matthew Leveson and the disappearance of three Aboriginal children - Evelyn Greenup, Clinton Speedy-Duroux and Colleen Walker - in Bowraville in the 1990s.
Matthew Leveson's mother, Faye Leveson, said she and her husband Mark were "heartbroken for Gary" and "absolutely devastated to think they've actually laid charges against him".
She said it was "a sad day for the NSW people and the NSW Police Force, because they have turned on the best".
"He hasn't been convicted yet, he's got to have his day in court and Mark and I are going to stand behind Gary," she told AAP on Friday.
"I just can't believe it's come to this. To me it's a witch hunt, tall poppy syndrome."
Leonie Duroux, the sister-in-law of Clinton Speedy-Duroux, who was 16 years old when he disappeared from the northern NSW town of Bowraville, also called the case a "witch-hunt".
"It's a f***ing disgrace to be honest," she told AAP.
"We're behind Gary 100 per cent, we support him and we will do anything we can to support him. Not that there's much that we can do except speak our mind I guess."
NSW Police said that while Jubelin had submitted his resignation, his immediate employment status was under review.
Australian Associated Press