Warning: This story contains distressing detailsA mum and her new boyfriend have been jailed for life for the "sadistic" abuse and murder of her two-year-old daughter. Isabelle Welsh was a "happy and thriving" child before her mother, Alexandra Walker, invited Harrison Simpson into their lives in Thornaby, Stockton, in June 2025, Teesside Crown Court heard. A judge said Isabelle was the victim of a campaign of violent and sexual abuse at the hands of those meant to love, care for and protect her. Simpson, 22, and Walker, 26, were both found guilty of murder and child cruelty, with Simpson also convicted of sexual abuse of a child. Simpson must serve a minimum of 28 and a half years and Walker 22 years.