A senior detective who investigated Brittany Higgins' rape allegations has been accused of showing bias in favour of her former colleague Bruce Lehrmann.
Australian Federal Police Detective Superintendent Scott Moller is being cross-examined at an independent inquiry into how the territory's justice system handled the high-profile investigation and aborted trial.
He was the lead officer who investigated Ms Higgins' allegation Mr Lehrmann raped her in 2019 inside the Parliament House office of then coalition minister Linda Reynolds after a night out.
Mr Lehrmann denies the allegation.
Top silk Mark Tedeschi KC, representing ACT Director of Public Prosecutions Shane Drumgold, drew the senior officer's attention to a comment he 'liked' on a LinkedIn post in December 2022.
It followed the announcement prosecutors would drop the charge against Mr Lehrmann due to fears about the impact of a second trial on Ms Higgins' mental health.
Det Supt Moller liked a comment that said: "Mr Lehrmann is innocent until proven otherwise."
The comment went on to say the former Liberal staffer did not deserve to be "negatively labelled for the rest of his life" and the author was "deeply shocked" by some of Mr Drumgold's reported comments on the case.
Mr Tedeschi suggested it was "entirely inappropriate" that Det Supt Moller had liked the comment in his capacity as a detective superintendent of the unsolved homicide squad.
He suggested this showed a bias from the investigator in favour of Mr Lehrmann.
"No, I don't agree with that. What I believe it shows is that I liked the comment, I agreed with the comment," Det Supt Moller said.
"I'll accept that in hindsight I probably shouldn't have liked the comment."
Det Supt Moller previously told the inquiry Mr Drumgold was dismissive of investigators' concerns there was not enough evidence to lay a charge.
He wanted to get supplementary legal advice on whether or not Mr Lehrmann should be charged because he believed the chief prosecutor had lost objectivity in the matter.
Investigators were concerned about putting the accused man before the court because of the presumption of innocence.
But the senior officer insisted once the prosecutor's office made a decision to move forward with charges after reviewing the evidence, police were absolutely professional.
That was at odds with the account given by Mr Drumgold, who told the inquiry police had a "passion" for the prosecution to fail.
Det Supt Moller also detailed his frustration with ACT Victims of Crime Commissioner Heidi Yates' involvement in the matter.
Ms Yates acted as a support person for Ms Higgins throughout the investigation and accompanied her to the trial.
The senior detective said Ms Yates' involvement was, in his opinion, "inappropriate".
"(Investigators) felt often that Ms Yates was speaking for Ms Higgins and not allowing Ms Higgins to speak," he said.
Ms Yates is expected to give evidence to the inquiry.
