Peter Sutcliffe was locked up for life in 1981 for the brutal murders of 13 women, but one mystery still remained - who WAS the cruel hoaxer behind the 'Wearside Jack' tape, which derailed the police investigation and led to three more women dying at the Yorkshire Ripper’s hands? Award-winning Daily Mail crime writer Stephen Wright speaks to retired Detective Chief Superintendent Chris Gregg, whose team unearthed a crucial clue more than two decades on.

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