The former lead detective in the William Tyrrell investigation has denied threatening a person of interest, telling a court he was always "professional and forthright".
Gary Jubelin was grilled in the witness box on Wednesday as part of William Spedding's claim against the state that he was wrongly charged with sexual assault so he could be pursued over the disappearance of William Tyrrell.
Mr Jubelin previously led Strike Force Rosann, the team investigating the disappearance of the three-year-old from a home in Kendall on the state's Mid North Coast almost eight years ago.
Mr Spedding was initially a prime suspect because he visited the Kendall home to repair a washing machine days before William disappeared but he has never been charged in relation to the missing toddler and was later ruled out as a suspect.
He was also acquitted of the 1987 sexual assaults at a trial in 2018 which heard evidence that the allegations had been fabricated by his former partner.
Mr Jubelin told the Supreme Court on Wednesday that the assault charges were not laid to "punish" Mr Spedding or further the strike force's investigation into the disappearance of William.
However, he accepted evidence from police progress reports that given the limited resources available to the strike force, the "only option" was to prioritise targeting Mr Spedding.
Adrian Canceri, Mr Spedding's barrister, suggested to Mr Jubelin he was so "desperate" to get to the bottom of what happened to William he threatened to "ruin" Mr Spedding.
"You said 'Mr Nice-Washing-Machine-Man, I'm going to ruin you'," Mr Canceri put to Mr Jubelin.
"I made no threats to Mr Spedding," Mr Jubelin replied.
"You said 'whenever they talk about William Tyrrell your name's going to come up as well and when they're talking about you, William Tyrrell's name is going to come up'," Mr Canceri said.
"I didn't say that," Mr Jubelin said.
The former detective, who has been credited with solving some of the state's most horrific crimes, said he was "professional and forthright" and did not act out of desperation or anger.
However, he acknowledged he "wouldn't be doing [his] job" if he didn't "take advantage" of the pressure Mr Spedding was under at the time.
The state maintains the charges came from a "professional, careful" investigation and were not influenced by the Tyrrell case.
The court has now heard from all witnesses and will adjourn until a later date for judgement.
