The tragic murder of British backpacker Grace Millane rocked New Zealand – but police caught on to the killer’s mistakes early on.

Police described the man who murdered British backpacker Grace Millane as a “very professional liar” – but a few key mistakes gave away the fact his story was a sham.

Jesse Kempson, 29, was found guilty of murder after strangling Ms Millane to death after they met on a Tinder date on December 1, 2018, in Auckland, The Sun reported.

The 21-year-old’s body was later discovered buried in a suitcase and a jury unanimously found Kempson guilty on November 22, 2019, following a two-week trial.

He was sentenced to life behind bars.

Chilling interviews Kempson gave to police, in which he at first brazenly lied about what happened on their date, then sickeningly tried to claim he killed her in a sex game that went wrong have been revealed.

ITV’s The Murder Of Grace Millane: Social Media Murders shows how at five key moments, investigators knew Kempson was lying.

‘Parted company with Grace’

A key part of the investigation saw a dedicated team sift through thousands of hours of CCTV.

During a police interview, the killer told Detective Sergeant Ewen Settle his account of what happened when the pair went on a date after matching on Tinder.

Det Sgt Settle said Kempson presented well and was wearing a three-piece suit with a pocket square – and while some of the things he said “were odd”, he added: “Some people are odd.”

Kempson told the officer they went to a burger restaurant and that the last time he saw Grace was around 8pm, when they parted company.

He then said he went to a pub where he had 10 drinks, before waking up at 9am or 10am the next day.

But CCTV footage showed him with Ms Millane clearly walking through the streets of Auckland back to his apartment.

“We got to the point where we knew that during the interview that enough CCTV had come through that pointed out he had been lying to us on one specific point,” Det Sgt Settle said.

Chilling footage from the lift shows Kempson and Ms Millane heading up to his apartment – the last time she would be seen alive.

Seen returning to his apartment

Later on in his interview, Kempson was handed a CCTV still by Det Sgt Settle who asked him: “Is that you?”

The officer told him that the picture was him coming back to his flat, which was in a hotel, at 8am on Sunday, and he hadn’t been asleep as he claimed.

Looking at Kempson directly in the eye, Det Sgt Settle said: “You haven’t told the truth.”

Calmly, Kempson replied: “Is there something you want to ask me?”

Detective Inspector Scott Beard, who led the investigation, said they always knew Kempson was lying.

“We knew he was a liar. He was comfortable and plausible in his lies. He was very professional,” he said.

“But we didn’t have any evidence that he had done anything to Grace.”

At that point, New Zealand law meant that Kempson had to be released after 48 hours of questioning.

Blood on the floor

Investigators had began carrying out a forensic examination of Kempson’s flat.

At first it seemed there was nothing to suggest Ms Millane has been murdered or any sign she had been there.

But forensics teams covered the floor with a chemical called luminol that glows when it reacts with traces of blood.

Images show purple patches across the floor where Grace’s blood had been, which indicated to officers that Kempson was lying.

“When you see the inside of Kempson’s apartment and you see the luminol, which is indicating all the blood in that room, you go, ‘Oh my gosh, what’s he done?’” Det Insp Beard said.

Clues on his phone

On December 8, Kempson’s phone was investigated for clues, in particular searches he had made and what time he had made them.

Around 1.30am, after he had killed Ms Millane, he was searching “how to make the hottest fires” as well as searching for pornography.

Officers were then told that his phone signal had been picked up on the Waitākere Ranges, outside Auckland, on the Monday.

Ms Millane’s body was later found buried there.

Story unravels with rough sex claim

Confronted with CCTV, Kempson finally admitted that he hadn’t in fact parted company with Ms Millane.

He said they had gone to a Mexican restaurant for drinks and then back to his apartment.

When they were there, he said Ms Millane brought up the novel Fifty Shades Of Grey, which centres on a woman’s sexual fantasies about being dominated by men.

Kempson then claimed they started having “violent sex”.

He told Det Sgt Settle that Ms Millane asked him to “hold her throat” and that all he remembered was falling asleep in the shower.

But police by then knew in detail how Ms Millane had died and it exposed Kempson’s story as a grotesque lie.

“What we know is that Kempson strangled Grace for seven to 10 minutes,” Det Insp Beard said.

“That’s not rough sex. That’s murder.”

Other aspects of his behaviour also led officers to believe his story was a fabrication.

CCTV showed him calmly buying a suitcase to dispose of her body and cleaning products, which he admitted were used to clean his apartment.

Other footage showed him carrying a bag with Ms Millane’s property stuffed into a plastic bag and then dumping it in a rubbish bin.

Police then took him to where she was buried, but Kempson continued to insist he hadn’t meant to kill her.

By then it was the end of the line for Kempson, who was once again asked if he meant to kill Ms Millane, which he denied.

At that point, Det Sgt Settle had enough to charge him.

“Jesse Kempson, you’re under arrest for the murder of Grace Millane,” he said.

This article originally appeared on The Sun and has been republished here with permission