Watch the full interview with Jonathan Hill
Even as a teenager I was always fascinated by this case. It was the summer of '89 and I was camping in the area with two friends not long after Peter and Gwenda Dixon had been murdered in cold blood on the Pembrokeshire Coast Path.
There were posters of the main suspect everywhere, and I can recall teasing my friend that the artist's sketch in the poster looked a little like him.
Witnessing all the activity in the aftermath of the murders was probably what sparked my interest in crime reporting.
It's difficult to overstate the impact that the killings had on the local community in this idyllic part of west Wales, especially when it happened just four years after another couple had been brutally murdered just five miles inland.
Fast forward seventeen years, and as a journalist for ITV Wales, I found myself closely involved with the reinvestigation of both double murders.
Back in 2007, we broke the news that detectives were using the latest forensic technology to take a fresh look at the killings.
It was an epic investigation lasting five years and I followed every twist and turn of the case, which ended with John Cooper being unmasked as a serial killer.
I couldn't believe it when I ended up playing a small part in the case. Detectives believed Cooper had taken part in the ITV game show 'Bullseye' and they asked me to help find the footage in the archives.
We eventually tracked down the footage and incredibly it turned out to have been filmed just a month before Cooper killed the Dixons.
The image of him playing darts for the star prize on the show also bore an uncanny resemblance to that artist's impression of the killer all those years ago.
That image went on to become part of the key evidence that saw Cooper convicted and jailed for life for the murders.
After working so closely with Steve Wilkins, the inspiring senior detective who led the investigation, we were encouraged by the then chief constable to write the definitive account of the case.
After many long hours at the kitchen table sifting through all Steve's notes we finally did it and the book was published.
Over the last three years Steve and I have worked closely with World Productions and writer Nick Stevens to turn the book into the gripping drama for ITV.
Filming began in Pembrokeshire last January and it was an absolute thrill to have the brilliant Welsh director Marc Evans behind the camera and the huge talent that is Luke Evans returning for his first major project in Wales.
With a strong Welsh cast and production crew, every effort was made to bring this story to the small screen with sensitivity and respect.
It was produced by Ed Talfan, the man behind the hit crime series Hinterland, and I knew we were in safe hands.
I will never forget Steve and I meeting the actors playing us in the drama at the very spot where we had broadcast news of the reinvestigation thirteen-years earlier.
I hope that the three-part drama is a fitting tribute to the extraordinary lengths the investigation team went to finally get justice for the victims.
Here are some of my personal pictures from filming.
The drama will air across three nights starting on Monday January 11.