A former senior detective in the police investigation into William Tyrrell's disappearance engaged in misconduct by failing to report prominent colleague Gary Jubelin's unlawful recording of a then-suspect, a tribunal has found.
Then-detective chief inspector Jubelin retired from the force and was later convicted of offences under the Surveillance Devices Act after it emerged he had illegally recorded widower Paul Savage in 2017.
Mr Savage lived across the road from the home where three-year-old William was last seen in Kendall on the NSW mid north coast in September 2014.
No warrant existed at the time to tape Mr Savage's calls.
In reasons published this week, the Industrial Relations Commission found Detective Senior Sergeant Craig Lambert "must have become aware" by early 2018 that his supervisor's call had been recorded without a warrant.
Det Sen Sgt Lambert had signed off on a case note about the taped call in February 2018 in his role as the officer in charge of the police investigation into William's disappearance.
He told the commission he'd reviewed thousands of case notes in the wide-ranging investigation.
But he didn't accept he would have been careless in reviewing, instead describing himself as pedantic in nature.
Det Sen Sgt Lambert took the matter to the industrial umpire after an internal police investigation found he'd twice engaged in misconduct, by knowing about the call and then been untruthful during an internal police investigation.
He successfully overturned a finding that he knew when the call was made in 2017 that it was being unlawfully recorded, arguing Jubelin had developed "tunnel vision" regarding Mr Savage and officer Lambert didn't concentrate on a call he considered an exercise in futility.
But he couldn't convince the commission he knew nothing come February 2018.
Lambert knew no warrant allowed Mr Savage's calls to be taped and viewing a case note suggesting the opposite was enough "to have 'rung alarm bells' and at the least have warranted further enquiry", the commission said.
"I find it implausible, and do not accept, that (Det Sen Sgt) Lambert would have adopted, to use the vernacular, a 'tick and flick' approach to the review of the Investigator's Note or of any product," commissioner Damian Sloan said.
As a result of the misconduct finding, the officer was transferred out of the homicide squad to another unit in State Crime Command in mid-2021.
The commission said the finding was a stain on "an otherwise unblemished disciplinary record".
The eight-year probe into William's disappearance is among the most extensive and expensive police investigations in NSW history.
William, who would have turned 11 in June, was last seen wearing a Spiderman suit before he went missing from his foster grandmother's home in Kendall in 2014.
Several searches of the home and adjacent bushland have failed to recover any relevant forensic evidence, an inquest has been told.
A coronial inquiry is ongoing, while a $1 million reward for information leading to a conviction remains on offer.
