Evil John Cooper was responsible for two separate double killings during the 80s. The twisted killer murdered siblings Richard and Helen Thomas with a shotgun then burned their bodies inside their three-storey manor house near Milford Haven, Wales in 1985.
He managed to evade the law and four years later he struck again, brutally killing hikers Peter and Gwenda Dixon on a coastal path in Pembrokeshire.
What stunned police was that Cooper had brazenly appeared on an episode of ITV gameshow Bullseye just weeks before he committed the second set of murders.
The case was reopened in 2006 and the vile criminal was caught using DNA evidence and archive footage of the TV show, before being jailed for life in 2011.
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