Sonia Sutcliffe first discovered that her husband, Peter, was leading a secret existence as 'the Yorkshire Ripper' only when he was arrested.

The wife of the 'Hillside Strangler' only learned of her husband's crimes when state police smashed down her door in search of him.

On finding out the truth, these innocents often experience a strange kind of guilt for not having recognised the killer in their home, as well as having to face the grim reality of betrayal and deceit.

Christopher Berry-Dee speaks directly to killers and their oblivious loved ones to get inside the minds of the men and women who fall for murderers.