Grace Millane was strangled by her killer in his Auckland hotel room following a Tinder date. It was 1 December 2018 - the day before what would have been her 22nd birthday.
The next day, while the backpacker's body was lying stuffed in a suitcase, the man - who cannot be named for legal reasons - took to the dating app again.
The woman he met in an Auckland bar has chosen to tell her story in the hope that by doing so she can help warn others about dating safety. Here, in her own words, she describes the time she spent with Ms Millane's murderer.
'He was really persistent'
We chatted for two weeks before we met up, the conversation was quite light, quite fun.
He was an Australian so we talked about Aussie things. He seemed like a nice, normal guy and when we agreed to meet I was happy to do that.
But then maybe five days before that he got really persistent. He would text me multiple times in a day and if I didn't reply he would ask if something was wrong.
He kept trying to bring the date forward and would forget I had told him I was busy.
It was unusual for someone to be that persistent. I have had guys before who are maybe a bit persistent but from nervous excitement - a different kind of excited.
It was just unusual that he could not possibly wait until Sunday. It felt very narcissistic.
'He had put on some weight'
He messaged me at around 09:00 (the morning after Ms Millane's murder) saying 'good morning, how are you?' and again at around 10:30. He said it was fine if I didn't feel like going on the date and that was when I messaged and said I would meet him.
We went to Revelry. It is a very standard bar, very popular, lots of people go there. More of a night-time bar - I had never drank there during the afternoon or day but it is open and he wanted to go there.
He was bigger than his photos showed; obviously he had put on some weight. He had big distinctive eyes and he was very, very clean. His clothes looked clean and he was well-groomed.
I asked him a lot of questions and he sort of talked. He tried to ask me a few questions but they weren't very in-depth questions. I thought he was nervous.
I guess because he had said one thing in messages about where he worked and a different thing on the date, I started to feel a bit uneasy.
'Murder was on his mind'
Because he was from Australia I asked him where he had met his friends and he said all his friends were police officers. He had met them at bars and they had invited him back for barbecues. He said his best friend was coming over to be a crown court prosecutor, so he sort of had this theme.
I think it was definitely on his mind and I think he was, in a weird way, trying to process something of what had happened, what he had done, with me. It was a very strange insight into what someone's brain does after they do something like that.
He had obviously been thinking about policemen, bodies, ways people can be killed, prosecution, justice and the court system and it just came out in a very strange way.
'It's crazy how a guy can make one mistake'
We talked about him being friends with lots of policemen. He said they were having a tough time because of bodies going missing in the Waitākere Ranges (where Millane's body would later be found). Police dogs can only smell four feet deep so if they are buried deeper than that, they can't find them.
I thought it was a bit strange but an interesting fact.
We got talking about poisonous snakes in Australia and he became quite animated about that. It was quite out there.
Then he told me this really bizarre story.
He said: "It's crazy how a guy can make one mistake and go to jail for the rest of his life."
He told me about a guy he knew in Australia who had consensual rough sex involving strangulation with his girlfriend but ended up accidentally killing her.
It was an accident, things went wrong and he was really upset by that because he loved her, but the guy got done for manslaughter and was sent down for a long time.
What we know now is this could have been him testing out his story on me.
He could see I was a bit uncomfortable and tried to talk about more mundane things. I didn't make a swift exit, I am quite used to dealing with all sorts of people, but it was definitely weird.
'My instincts kicked in'
Before we said goodbye he said "my car is this way". My car was down that same road but by that stage, I was feeling uneasy and my instincts had just kicked in telling me to walk a different way.
He was also a lot bigger than me so if something went wrong I knew I wouldn't be able to defend myself.
In hindsight it was a good decision. It was my intuition sense, my brain was saying "this was strange, that was strange".
It is really strange in hindsight to think of [Grace being dead in his room]. I don't think it is in the realm of what normal human brains can comprehend.
It is hard to look back and think that that had just happened to her. There's nothing I could have done, and I know that now, but it is still really hard to come to terms with that.
'It has made me go a little slower'
I do think if it had been a date in the evening potentially I could have been a victim. I take quite a lot of solace in the fact I do have my wits about me and do take safety in online dating quite seriously.
And that is nothing against any woman who is willing to go home with someone on the first date.
I do want to just say to young women to take one more step in your thinking when you are on a date to see how well you know this person.
Since then, I have been on dates with lovely, trustworthy men but thought "how well do I really know them"? It has made me go a little slower, divulge less information.
I know in modern dating it is quite common to give people your Instagram handle but you are giving people access to a lot of personal information.
It is really dangerous and I want to just encourage people to step back. There is nothing wrong with taking a step back, taking it slow and pacing yourself a bit.
Alcohol has a big effect, it is part of the social fabric of dating and part of life these days, but it still comes with massive risk. Women need to be really aware of how much they are drinking on dates and unfortunately drinks are sometimes spiked.
We live in this world where people are still idealistic about how things should be on dates but incidents like these take things back 10, 20 years, where women are still having to grip their keys between their fingers or can't leave a drink on the table.
We aren't as developed as we think we are in areas such as dating. Technology has got ahead of us. I think people are as they always are.
I think with the advancement of technology we thought we would become more refined but we are just the same but with new technology.
I think the invention of dating apps is a wonderful thing and I wouldn't want to live in a world without that, but I just wish for a world where women don't have to think about their safety all the time.
- As told to the BBC's Doug Faulkner.