National leader Simon Bridges was not aware of a police investigation into one of his party's MPs until media got in touch.
Sarah Dowie, electorate MP for Invercargill, allegedly sent a text message to former colleague Jami-Lee Ross in August, telling him he deserved to die.
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The pair reportedly had a long-term affair, which ended mid-2018. The text was sent in August, and Mr Ross says it triggered his breakdown in October, which saw him sectioned under the Mental Health Act.
An anonymous person made a complaint with police over the text in December, under the Harmful Digital Communications Act. Mr Ross says he doesn't know who it was.
Newshub and other media outlets decided against naming Ms Dowie last year when rumours of her involvement began circling, but Newshub political editor Tova O'Brien told The AM Show on Friday the existence of a police investigation meant naming her was now in the public interest.
When Newshub approached National for comment, Mr Bridges wasn't aware Ms Dowie was being investigated, and said police were yet to get in touch. Both he and Ms Dowie declined to comment.
"It seems strange as well that the police haven't contacted Sarah Dowie, which is what the National Party told us," said O'Brien.
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The party put out a statement.
"The National Party is aware of media reports of a police investigation but has not heard from police. If there is an investigation, then we would expect people to cooperate fully."
The maximum punishment under the Harmful Digital Communications Act for inciting a person to suicide - even if they don't carry it out - is three years in prison. MPs convicted of a crime that has a potential punishment of at least two years in prison are automatically booted from Parliament, even if that's not the sentence that's handed down.
Mr Bridges and other National MPs have said they don't want to talk about Mr Ross anymore, after he quit the party and was unanimously expelled on the same day.
"Bluntly speaking, Jami-Lee Ross is no longer my problem," he said on Monday. "We expelled him from the caucus, it took up a month or two of time, my time as leader of the Opposition. It was a distraction."
O'Brien says Mr Bridges is dreaming "if when he got back to Tauranga over the holidays and put on his three-quarter length pants [he] thought that he could move on from the Jami-Lee Ross debacle".
"There was no chance. This was always going to come up again this year. Jami-Lee Ross was always going to return to Parliament."
Mr Ross is expected to deliver his first speech to Parliament as an independent MP in February.
Where to find help and support:
Need to Talk? - Call or text 1737
Lifeline - 0800 543 354 or (09) 5222 999 within Auckland
Samaritans - 0800 726 666
- Depression Helpline - 0800 111 757
- Suicide Crisis Helpline - 0508 828 865 (0508 TAUTOKO)