Gripping murder drama A Confession tells the real-life tragic stories of Sian O’Callaghan and Becky Godden-Edwards, both killed by evil Christopher Halliwell, and the detective who battled to bring him to justice. The ITV series, starring Martin Freeman as Det Supt Steve Fulcher and Imelda Staunton as Becky’s mum Karen, has captivated viewers, pulling in an audience of five million for its opening episode. Here, in an exclusive extract from her new book A Killer’s Confession: And a Mother’s Fight for the Truth, Karen Edwards, shares her heartbreaking story… Mum, I think you need to come here.” My son, Steven, had answered the knock on the front door. Now he was calling me from the kitchen. I knew then, even before I looked down the hallway. Maybe I caught the tone of Steven’s voice, a nuance that would have been lost on anyone else. A mother’s instinct, perhaps. Cold fear gripped me. As soon as I saw the police officer I knew why he was standing there. Becky, on what would have been her 29th birthday. I recognised the officer straight away because I’d seen him on the television. Everyone knew his name. For the last two weeks a police…