He was Dartmoor's most infamous prisoner – dubbed "Britain's most violent criminal" in the Press – and an associate of the notorious Kray brothers.Frank Mitchell, who had earned his "Mad Axeman" moniker after holding an elderly couple hostage with an axe, had been sent to Dartmoor for life.And yet despite his fearsome reputation and propensity for extreme violence, he was spirited off the moor 50 years ago – but would never be seen again.Read more: Revealed - Dartmoor Prison's...
