The inside story from the policewoman who helped catch Peter Falconio's killer.

“Hey, boss, you better come to work. A bloke’s missing and his missus reckons someone’s shot him.”

Those words by a young Northern Territory police officer would forever change the life of Det Supt Colleen Gwynne.

They marked the beginning of a case that she would ultimately lead, a case that would captivate a nation, divide public opinion and go down as one of the most famous in Australian criminal history – the murder of 28-year-old British backpacker Peter Falconio.

Gwynn has shared the inside story with The Guardian.

Northern Territory Police, via Getty.

Crouching alone under the saltbush on the edge of the Stuart Highway six months after Falconio's disappearance, Gywnn tried to put herself inside the crime.

She replayed the details of that fateful night in her mind, over and over.

The white ute with hazard lights blinking. The helpful backpackers in the Kombi who stopped to help. Male voices discussing something about an exhaust pipe. A gunshot. Lees being hit on the head, dragged from the front seat of the Kombi, bound and pushed inside the ute. The anxious killer returning to her boyfriend's body. A brief moment in which to escape, to find a hiding place in under the very bush where Gwynn was now huddled.

“I felt extremely vulnerable out there,” Gwynne told The Guardian. “I could hear my own heartbeat.

“That’s when it felt really real for me. I understood what this woman had been through and it was terrifying. What she endured and her fight for survival was just remarkable.”

Northern Territory Police, via Getty.

Having recently been promoted to Superintedent, the case was Gwynne's to solve.

“To deal with the anxieties, I worked day and night and I read every little piece of that case,” she said. “I was up until two or three in the morning, reading, reading, reading. After that, I knew what I needed to do … I had to put together a winning team.”

Among them was a quiet, young female detective who would ultimately obtain the key evidence to pin down local mechanic and interstate drug runner Bradley John Murdoch. That evidence? A DNA sample from his brother that linked Murdoch to the crime scene.

“I couldn’t believe we had a match. We now know who touched Joanne Lees on her shirt. We now know who touched the gear stick in the Kombi. It was Bradley John Murdoch,” said Gwynn.

With the police and the press on his tail, Murdoch fled. But it wasn't long before he committed another crime, this time in South Australia. Local police tracked him down and detained him for the suspected rape and abduction of a woman and her 12-year-old daughter in Port Augusta.

Gwynn finally had her man.

“When we arrived at Yatala prison, my heart was beating like you wouldn’t believe,” she told The Guardian. “I was finally going to meet this man. There was an element of excitement too. I’d spent the entire previous night prepping for the interview. I was ready.”

But then face to face with this towering figure, spitting and screaming in her face, a man capable of cold-hearted violence, Gwynn's traumatic childhood came bubbling to the surface.

“There was a remarkable resemblance between Murdoch and my father, who was the most intimidating and violent man, who made my upbringing a living nightmare,” she said. “I never could stand up to my father but I wasn’t going to take a backwards step now. I played the game and I won. He took the first step back.”

Image: Getty.

With Murdoch in custody and a trial looming, Gwynn travelled to England to re-interview Lees, then later made a visit to the home of Falconio's parents in Yorkshire - a visit that she will remember for the rest of her life.

“Joan Falconio was so distraught she couldn’t get out of bed to talk to me. It took her an hour,” said Gwynn.

“I drank about 30 cups of tea and went to the toilet about every four minutes. That’s a pretty good way to break the ice.”

Eventually, the small talk ended, Gwynne took a deep breath and said what she had come to say: “We know who did this and we’re going to convict him.”

Silence. Then Joan Falconio got up, walked across the living room and hugged her.

Peter Falconio's family and partner, Joanne Lees, outside court. Image: Getty.

When the jury delivered a guilty verdict on 13 December 2005, four and a half years after Murdoch flagged down the Kombi near Barrow Creek, Gwynn was sitting right there in the front row of the courtroom.

Despite Falconio's body never being found, Murdoch was convicted and sentenced to life with 28 years non-parole.

“I didn’t know how to feel,” said Gwynne. “I wanted to cry. I wanted to laugh. I felt numb."

Looking around the courtroom, she locked eyes with the woman to whom she had made such a huge promise, the weight of it lifting from her shoulders, reports The Guardian.

“There was Joan Falconio and she mouthed ‘thank you’ to me and I had to remove myself from the courtroom. The emotion was overwhelming and I had to find somewhere I could just cry,” said Gwynne.

“That was the moment that marked the end of my police career. I would never equal such a challenge. It’s like being best on ground in consecutive grand finals. There’s nothing left after that.”