Barbara Kuriger is understood to be the National MP who dobbed in Todd Muller for speaking to a media outlet in a conversation that led to him being forced to announce he was resigning from Parliament.
On Wednesday, Muller announced he was resigning from Parliament at the next election – an announcement that followed what one MP described as a "brutal" caucus meeting in which he was given the ultimatum of either walking or being suspended from caucus.
The NZ Herald was told that showdown was prompted by National Party leader Judith Collins learning that Muller was one of the unnamed MPs quoted in a Newsroom story about the return of Harete Hipango. The quotes were not flattering.
Collins confronted Muller earlier on Tuesday with the accusation he was one of those MPs, and Muller had admitted it.
The NZ Herald has now been told Collins was alerted to Muller's involvement by Kuriger, the party's former whip under both Simon Bridges and Muller's leadership.
It is understood Muller was with Kuriger when he spoke to Newsroom, and Kuriger overheard it.
Kuriger and Muller have both been approached for comment.
The dobbing in sparked a caucus meeting which had all the drama of a documentary on wild animals battling at the savannah water hole.
Muller tried to hold his ground and stare down Collins – only to be taken down as the pack turned on him.
There were allegations, betrayals, acts of revenge and cowards covering their own butts.
The NZ Herald was told the 10pm Tuesday meeting was called after Collins spoke to Muller earlier in the day about his involvement in that article.
Muller admitted it and Collins then told him to resign, saying she would move to suspend him from caucus if he refused.
Late on Tuesday, Collins called a caucus meeting for 10pm and delivered the ultimatum to the MPs.
Either Muller left voluntarily, or caucus would vote to suspend him. The threat of suspension was potentially a risky move for Collins, because it would have effectively doubled as a confidence vote in her.
If a leader puts up a vote on something that significant and loses, it is a vote against the leader.
There is some disquiet among MPs about the way Muller was dealt with, especially given Muller's mental health issues. One MP described the meeting as "brutal".
Some also questioned whether the punishment was proportionate to the crime.
But there was little doubt among them that a vote to suspend Muller would have passed at that meeting.
Some agreed with the need for a zero-tolerance approach to those whispering or leaking to media.
Self-interest came into play for some, and for others there was lingering resentment over the rolling of Simon Bridges or Muller's time as leader.
Some simply believed it would have been smoother for the party had Muller left after his leadership ended, rather than stay and try to rebuild his political career.
At that meeting, Muller apologised and tried to defend himself and hold his ground, but it was too late.
Collins had already made her own view clear and caucus knew it.
At that meeting, significant effort was put in to persuade Muller to resign rather than force a vote to suspend him.
The final nail was hammered in by Chris Bishop: Muller's old "numbers" man who played a critical part in engineering Muller's coup of Bridges.
The Herald was told Bishop urged Muller to resign and go with dignity rather than force a messy, bloody suspension - using that well-trodden phrase "for the good of the party".
The reason to avoid a suspension was partly to avoid the added scandal and drama of kicking an MP out of the party, a drama the party did not need.
But it was also the lesson of Jami Lee Ross, who lashed out in dramatic and infamous fashion against National and Bridges after he was accused of leaking Bridges' travel expenses. Ross was suspended, turned on his former friends, made allegations against Bridges and released secret recordings of his conversations with Bridges.
Muller is not like Ross, but the fear was that if Muller was forced out rather than persuaded to "resign with dignity" he would turn on the party.
There were also concerns about the impact on Muller's own health.
It seemed a very tough penalty for what amounts to a low-grade offence.
It is not unknown for MPs to brief media, or pass an opinion on someone or something on the quiet. But that falls short of a genuine leak. This was not a leak of information, or of confidential caucus discussions, or even comments critical of the leader.
It is a mere shadow of the transgressions that led to Ross' suspension from National's caucus.
Many of the MPs will be well aware that Muller is simply the fall guy: the one man taking the fall for something a fair few of themselves have done over recent years.
Leaks had plagued National for years, and Collins wanted to make an example of someone.
National's MPs have now been ordered not to talk to media about the meeting or Muller.
On Wednesday evening, soon after the NZ Herald broke the news broke of the real reason behind Muller's resignation, Bridges posted on Facebook and Instagram.
It was a photo of himself talking to the media ahead of National's regular weekly caucus meeting. He wrote: "Speaking with the press is a normal but important part of being in politics. For me it's an opportunity to speak not only to journalists, but to all New Zealanders."
On any day, it would have been an innocuous post but given the timing some have interpreted it as either a small sign of solidarity with Muller's plight – or a message that a leader can only go so far in gagging MPs.
As this was going on, Collins was contending with a looming story by the Whanganui Chronicle and the NZ Herald about Hipango – allegations she had been reported for inappropriate spending on her parliamentary card in the last term, including items of furniture such as a sofa.
That story broke the morning after the caucus meeting. A couple of hours later, Muller's resignation was announced.
Collins and Hipango have so far been saved from the usual scrutiny by Covid-19. The news an Australian visitor had since tested positive for Covid-19 threw Wellington into level 2.
That news overshadowed National's woes.
But there was something of a triumphal air about Collins after her victory over Muller.
On Thursday she was asked about the ructions and disunity on Hokonui radio's The Muster programme. She replied: "Sometime you have to break a few eggs to make the omelette".
The trouble with making omelettes is that they can easily turn into scrambled eggs.