In the sixth and final episode of Death of a Codebreaker, Dr Sian Williams asks what justice for Gareth Williams would look like. She hears from Jim Frazer, the forensic scientist who carried out a review into the case 11 years ago as well Angela Gallop who has reviewed dozens of cold cases over...

Young Welshman Gareth Williams was found naked inside a relatively small bag in his bath in 2010. And another theory is that he was the victim of a bizarre sex game gone wrong. There are suggestions he may have had an interest in Claustrophilia - pleasure derived from being in a confined space....

With so many unanswered questions, different theories about what exactly happened to young Welshman Gareth Williams in summer 2010 remain rife. One suggestion is that he was assassinated by a rogue state. A former KGB intelligence officer, an ex-Government Minister and the wife of murdered...