The terrifying true story of a woman who lived with one of Britain's most notorious murderers for three years before he attacked her with an axe is the focus of a gripping new ITV drama, but who is the real Delia Balmer?

Until I Kill You features Bafta-winning Anna Maxwell Martin who stars as Delia Balmer and is based on a memoir written by Delia Balmer herself where she documents her violent relationship with serial killer John Sweeney. We take a look at the real story behind their relationship and how Delia discovered her boyfriend was not who he initially seemed.