Jesse Kempson seemed "relatively plausible" when police met initially met him, but it didn't take long before they started uncovering his lies.
The officer in charge of the investigation, Detective Inspector Scott Beard, also told Newstalk ZB this morning that no matter the reasons for his offending against women and the murder of Grace Millane, Kempson was responsible for his own actions.
It was finally able to be revealed yesterday that the 28-year-old was not only responsible for Millane's murder but also sexual offending against two other women, the trials of which had remained in a shroud of secrecy.
Beard said today that it wasn't until they managed to get CCTV footage that they realised Kempson was lying to them.
"Initially he was quite plausible and it wasn't until through that first interview and some of the investigation team managed to get through some of that CCTV that we realised that he told us a lie.
"From that moment we started thinking 'right, we're on the right track here, we've now got to find Grace and prove that he was the last one that was with her'."
Jesse Kempson caught on CityLife Hotel's CCTV transporting Grace Millane's body to her vehicle and later disposal.
Uncovering one lie, the investigation team had the obvious realisation that there were likely more to uncover.
"Absolutely, of course, and in the second interview, a couple of days later, it was a completely different story."
Asked for his opinion about Kempson keeping his name secret for so long, Beard said police had no problem with it as he had a right to a fair trial but he could understand some of the frustration by the public.
"We had no issue from the police perspective on the name suppression, it was proper, it was right.
"I understand the frustration from members of the public out there but we had two other victims out there, we had their trials, he had a right to a fair trial but they also had a right to have their say in court."
Jesse Kempson caught on CCTV buying a spade to bury Grace Millane's body.
As for the victims of his earlier offending, who came forward after noticing his image being circulated by overseas media, Beard said it had been hard to learn it was the same man who killed Millane.
"The two victims who gave evidence in court, the two trials, just their evidence alone you could tell how devastated they were with the realisation of who he was."
As for Kempson himself, Beard said his upbringing was mentioned in court but "at end of the day, he's accountable for his actions and we had three victims here and for the Millane family they will never have Grace back".
He had been speaking with Gillian Millane today and felt for how much she and the rest of the family have had to deal with.
"For three years now she's basically been numb. She's had her own health scares, she's had Grace's situation and of course last year [husband] David was sick and recently died and so she's been dealing with the funeral arrangements and they've had Covid over in the UK and so it's been really tough for her.
"She hasn't really had time to grieve or move on and Christmas is coming and they're in lockdown.
"I'm sure the public of New Zealand and in the United Kingdom can't help but feel for the Millane family."

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