Murder Uncovered: How a young girl and rookie cop caught serial killers David and Catherine Birnie

In an interview room inside a small suburban Perth police station, a nervous young policewoman comes face-to-face with a terrified teenager.

The young girl claims she has escaped the clutches of monsters who abducted her at knifepoint and kept her prisoner in a house where she was tormented and raped.

And in those first critical hours, only one person believes her — the rookie officer, only several months out of the police academy.

It was November 10, 1986 and Constable Laura Hancock, 22, had never taken a statement before, let alone from a rape victim, when she was tasked with interviewing 17-year-old Kate Moir.

Ms Moir turned out to be the only victim to survive the killing spree of deranged couple David and Catherine Birnie, who had terrorised Perth that past month.

Ms Moir’s courageous escape and Ms Hancock’s persistence with her superiors to take the teen’s story seriously ultimately led police to crack one of Australia’s most notorious serial killing cases.

Ms Hancock’s unheralded role in the case and the strong bond she still shares with Ms Moir — despite the fact the women have not seen each other in the past 30 years — are revealed in Seven’s new crime investigation series, Murder Uncovered.

The only female police officer on duty at Palmyra Police Station, Ms Hancock believed her superiors would not have had her interview Ms Moir if they had believed the teenager.

It was the intricacies of what Ms Moir was saying that convinced Ms Hancock she was telling the truth and that urgent action was needed to catch the culprits.

Ms Moir appeared to be in shock, looked drained and tired, and showed no outward emotion, but was very factual in her details.

To the junior cop, Ms Moir “oozed honesty”.

“What she did say to me, she believed that there were, there had been others and that they had died and she was going to die, had she not escaped she was going to die and she was very emphatic with that,” Ms Hancock told Murder Uncovered.

“(She was saying) ‘Well look I got picked up here ... they put me in the car, I had ties on my hands, they took me to the house, he raped me twice, he did this, I got away and the dogs attacked me’.”

It was really just very, very factual.

“I pegged down a few intricate details of which she answered immediately, no hesitation and very detailed,” Ms Hancock said.

“You can’t bed down those intricacies if you’re going to tell just a made-up story. (She wasn’t saying) ‘oh my God this is what I’ve just been through, poor me’. It was just the focus of ‘listen to me, here’s my story, this is why, this is how and this is who, go get them’.”

Ms Moir had paid attention to minute details during her horrific nightmare, telling Ms Hancock the movie Rocky was in the VCR, Dire Straits was in the cassette player and although her captors used false names in front of her, she remembered a name she saw on a medicine bottle — David Birnie.

Ms Moir even told Ms Hancock she had drawn pictures and hidden them in the house so that someone would know she had been there.

During various points in the interview, Ms Hancock left the room to plead the teenager’s case with her senior colleagues. Asked what changed the minds of her sceptical superiors, Ms Hancock said it must have been her “persistence and nagging”.

However it was only when Ms Moir mentioned the name David Birnie, who had a lengthy criminal record at that stage, that major crime police were called in and took over.

Hours earlier, Ms Moir had seized an opportunity to escape through a window while Catherine Birnie wasn’t watching and David Birnie was at work, running to the local shopping centre and begging for help and the police.

Catherine Birnie was arrested at the couple’s Moorhouse Street home in Willagee, but not before she had incinerated vital evidence in the fireplace on instruction by her partner after Ms Moir’s escape.

As Ms Moir sat in a police car outside the house, Ms Hancock was inside with other cops and saw for herself chains and handcuffs in the master bedroom and confirmed the finer details of what Ms Moir had told her were true — the Rocky tape was indeed in the VCR and her drawings were hidden under the mattress.

“It’s just a strength and a focus of ensuring that they were captured and held to account, in a 17-year-old (account) what’s more, remarkable,” Ms Hancock said of Ms Moir.

In separate police interviews, David Birnie insisted he had picked up Ms Moir hitch-hiking and that the sex had been consensual, while Catherine Birnie claimed she had no idea who the teenager was.

Police knew they were on the front foot from the outset.

But hours of grilling had proven unsuccessful and a gamble by detective Vince Katich paid off when he told David Birnie “let’s go get a shovel and dig up some shallow graves”.

The weasel-like Birnie caved to the bluff, responding to the detectives’ shock: “There’s four.”

The Birnies then led police to the graves of Mary Neilson, Susannah Candy, Noelene Patterson and Denise Brown — the four women they had kidnapped or lured to their house of horrors, raped, tortured and killed.

Ms Hancock said it was emotional parting ways with Ms Moir, with the pair only reuniting more than three decades later for their first interview together.

“It was extremely emotional to be able to give back someone their child, but unfortunately we weren’t able to do that with the others,” she said.

Soon after saying goodbye to Ms Moir, Ms Hancock had to guard an unrepentant Catherine Birnie at Fremantle Police Station.

“It took every ounce of control I had just to stay professional... because I’ve just let go of this girl who was about to be killed by her and here I am now looking at you. Yeah, it was tough,” she said.

“She was just talking like how logical what they did was. You know, you pick these girls up to satisfy David Birnie and our own needs and then after that well you can’t just let them go... you have to kill them.”

Ms Hancock also recalled a time when she witnessed Catherine Birnie’s twisted obsession with her partner-in-crime after escorting her to a shopping centre where she’d disposed of victims’ clothes.

“She had a can that David had bought her when he first arrived at the station, it was lemonade or a can of cool drink and it was empty but she wouldn’t release it and it was like a security blanket because it’s a connection with David,” she said.

Ms Hancock also had a chilling encounter with David Birnie during her time working on the case, when he used perverse mind games on her, taunting her about a sword she had seen in his house.

“And his words to me when he was in that cell (were) that I should have been the first girl he picked up,” she said. “And I said, ‘What do you mean’... and he said, ‘Because if I got you, you would have killed me’. And he told me that I ‘would have used the sword on the wall’.

“I said ‘my oath I would have’, he said ‘yeah, but then these other girls wouldn’t be dead, Laura, so how do you feel about that now, it’s your fault’.

“Although my conscious mind ... I know that’s ridiculous ... but in my subconscious at night when I was sleeping that would replay and replay and how I would do it would replay and replay and those words — how I would have killed him.”

Det. Katich said Ms Moir’s bravery saved untold lives, describing the Birnies as “wholesale butchers at the end” who would have kept killing if they had not been caught.

Ms Moir, who still recalls how her father came into her bedroom crying at 5am to tell her police had dug up four bodies, said she believed the Birnies deserved the death penalty, which had been abolished in WA two years prior.

Ms Hancock believes Catherine Birnie should never be released from prison. David Birnie meantime, hung himself in his cell at Casuarina Prison in 2005.

Despite decades of distance, Ms Hancock and Ms Moir are sure they will be friends for life.

Ms Moir, who is campaigning for tougher parole laws for murderers, said sharing a traumatic experience forged their closeness.

Murder Uncovered airs Wednesday 9pm on Seven.