The suspects have all denied it. The trail of clues has gone cold. The opposition says there's no evidence it even happened.
But now the question of whether someone in New Zealand's parliament called Prime Minister Jacinda Ardern a "stupid little girl" has led to an extraordinary stoush in the country's corridors of power.
During a heated debate in the house this month, Speaker Trevor Mallard halted proceedings demanding an apology from whichever member in the opposition benches had made a "very sexist remark".
He later confirmed the exact phrase he had heard.
Video footage of the debate proved little use - and subsequently about a dozen male MPs reckoned by Newshub to be possible suspects all denied making the comment or hearing it.
The matter seemed buried, until National Party and opposition leader Simon Bridges on Wednesday said there was "no evidence" it had actually happened.
"Those sort of remarks shouldn't be said. But I have no evidence that they were," he told Stuff.
"I sit nearer to those members than the Speaker or the other side, I didn't hear them. No one has told me that they heard them and no one has said that they said them."
While audio recordings of the debate have failed to turn up a smoking gun, Mr Mallard has stood by what he heard.
"He can confirm the comment he heard in the house on the day was 'stupid little girl'," his office said in a statement on Wednesday.
That confirmation has spurred an unusually strong rebuke from National, which says it's "unacceptable" the Speaker has been "pushing" a story that harms the opposition and can't be verified.
"Our confidence in you as a Speaker has been significantly shaken," shadow leader Gerry Brownlee said in an letter, demanding a "full explanation" before parliament resumed on Thursday.
"There is an expectation that the Speaker will behave in a neutral fashion and we're having a little trouble at the moment seeing evidence of that," he told media.
Meanwhile, Ms Ardern herself seemed less concerned, telling reporters she couldn't pick out the exact comment among the noise of the debating chamber.
"Look, you know, plenty of this stuff flies around the house," she said earlier in the day.
"But, as I've always said, my preference is always to play the ball, not the man."
