Isabelle Rose Welsh was murdered by her mother and her boyfriendA mother and her new boyfriend have been jailed for life for the sadistic murder of her two-year-old toddler who was also sexually assaulted. Alexandra Walker, 26, and her boyfriend Harrison Simpson, 22, were convicted of murder and child cruelty this week following a trial at Teesside Crown Court. He was also convicted of sexually assaulting Isabelle, while her mother was cleared of that charge. Jurors were told that Isabelle had been a happy, healthy child until her mother started dating Simpson last summer. She jailed Simpson, saying only he will know the motivation for what happened.