Throughout the early 90s young boys would be found dead after sniffing glue and being trapped in derelict buildings which caught fire. But when it kept happening, cops got suspicious. They soon found they were actually being systematically murdered by a man called Steven Grieveson, dubbed the Sunderland strangler in a case which still haunts the town. His is a name few will know, but he's regarded as one of the most dangerous killers in the UK.