Also the psychopath they

off shotgun.

So, having been released from prison on licence in 2008 after a decade inside, Cooper was rearrested and charged with the four murders.

In an even more bizarre twist, Cooper’s love of darts saw him implicated further still as old footage surfaced of him competing on Bullseye, the Sunday teatime game show presented by the late Jim Bowen.

The episode in question had been recorded in May 1989, exactly a month before the Dixon murders and, in a pre-round ramble with the programme’s host, Cooper talked about his hobbies and love of the greatoutdoors, detailing at length the geography of the West Wales countryside.

More specifically, it showed he had intimate knowledge of the area where the English hiking couple had been killed. His appearance at the time, with scruffy mullet and moustache, also proved a dead-ringer for the sketch artist’s impression of the suspect from the original inquiry.

In addition, a Swansea Crown Court jury further convicted Cooper of sticking up five terrified teenagers at gunpoint in woods on Milford Haven’s Mount Estate in 1996, where he raped one 16-year-old girl and indecently assaulted another, aged 15.

The judge handed down four “whole life” sentences, telling the 66-year-old: “The murders were of such evil wickedness the mandatory sentence of life will mean just that.”

Wagging his finger at the bench as he got taken down, Cooper again protested his innocence and warned that the truth would, one day, “all come out on the internet”. Nothing ever did, though. Cooper has since been implicated in five other murders and had his last appeal rejected in November 2012.

John Cooper outside Swansea Crown Court in 2011 Serial Killer John William Cooper appearing on the gameshow Bullseye and, right, an artist’s impression of the man police were hunting at the time. Below, the gun Cooper used to murder the Dixons Police on the Pembrokeshire coastal path at the scene of the Dixons’ murders in 1989