For five years, Peter Sutcliffe, known as the Yorkshire Ripper, hunted and killed defenceless women, mutilating their bodies with hammers and screwdrivers. But could his murder spree have been stopped earlier? In the wake of the Ripper's death this month, award-winning Daily Mail crime writer Stephen Wright talks to retired Detective Chief Superintendent Chris Gregg, who joined the Ripper investigation as a rookie policeman in the late 1970s - and witnessed the cruel hoaxes and fatal police errors that allowed Sutcliffe to remain at large. In powerful and poignant testimony, the respected ex head of CID at West Yorkshire Police discusses the ‘Life on Mars’ culture in the force at the time of the Ripper murders, and the harrowing stories of Sutcliffe’s victims.