The evidence from an initial investigation into disgraced National party MP Andrew Falloon did not meet the threshold for prosecution but police say they are now aware of further allegations and are appealing for anyone with information to come forward.
The Rangitata MP has today quit parliament effective immediately in the face of growing claims he sent unsolicited pornographic material to more than one woman.
His own party leader Judith Collins expressed no confidence in him after initially saying Falloon was suffering from significant mental health issues.
Police investigated a complaint at the beginning of July but did not take it further because of a lack of evidence.
So what is needed to meet the level for prosecution?
"What I understand has been alleged could be captured by the Harmful Digital Communications Act," employment and technology specialist lawyer Gareth Abdinor told Checkpoint.
"Now that Act covers all sorts of digital communications, including emails, text messages, websites, social media posts. It's really very broad.
"And that Act sets out ten principles that would capture explicit content, and essentially prohibits any digital communications that are grossly offensive, indecent or obscene, that would be grossly offensive to a reasonable person - anything that's threatening," he said.
"If you have a situation where there is consent between two people, an image is created – the problem with that is it is almost impossible to control the digital image, and it can be accessed without authorisation for, for example by hackers.
"But even if we don't look at hackers, if you consent to someone taking an image just to be shared between the two of you and then they share it with a third party, potentially, you've got breach of the Harmful Digital Communications Act and you've also most likely got a breach of privacy."
Is nudity enough to reach that threshold of offensiveness?
"There has been a lot of discussion about this is. There's a very famous quote from a court case in the United States where they were dealing with pornography and the judge said it's very difficult to define but you know it when you see it.
"It's very difficult to say what is going to be pornographic and what isn't. But most of the cases I'm aware of where this has come before the courts, it is quite obvious, and often falls into that category of revenge porn, where someone has obtained an image with consent and then after a relationship breaks down they share that image with the express purpose of hurting or embarrassing the other party."
Abdinor said there is a big difference between two consenting people willingly sharing risqué electronic messages and someone, potentially in a position of power, sending unsolicited images with someone significantly younger or more junior.
"So that may well be why the police are involved," in the Falloon case, he said.
"I imagine they would be looking for a pattern of behaviour. Certainly, if something has happened many times, or the suggestion that a position of power has been misused numerous times. It may suggest that that other behaviour has taken place. Very difficult to say."
He said mental illness may not be a legitimate defence in a potential case, but it is relevant and he would be surprised if it was not considered by the police.