A mother and her new boyfriend have been convicted of murdering her two-year-old daughter, Isabelle Welsh. The child was sexually abused before sustaining a catastrophic head injury. She sustained 21 broken bones before collapsing last September at their Thornaby, Teesside, home.Her mother, Alexandra Walker, 26, and Harrison Simpson, 22, denied murder, allowing the death of a child, sexual assault and child cruelty.After almost seven hours of deliberations, a jury at Teesside Crown Court convicted Simpson unanimously, and Walker by a majority of 11 to one, of murder.They also convicted the pair of child cruelty.Simpson was convicted of sexual assault on the toddler, while Walker was cleared of that charge.Ms Justice Norton thanked the jury for their work on such a “difficult” case.She will pass sentence on Thursday morning.As Isabelle was dying, Walker delayed ringing 999 despite Googling “why would my toddler be bleeding” and she smoked a cigarette in her kitchen.Alexandra Walker, 26, and Harrison Simpson, 22, were convicted at Teesside Crown Court. (PA Archive)She first called her step-father to come round and it was only on his instruction that she finally alerted the emergency services.When paramedics arrived within a minute, they found bruises all over the little girl’s body including to her head, neck, abdomen, back and private parts; there was blood in her nappy and sick on her face.Isabelle was not breathing and was cold to the touch as medics battled in vain to save her and she died the next day in hospital.A post mortem revealed the extent of her injuries – that her skull was fractured, her brain damaged and that she had been sexually assaulted.Experts told the jury that Isabelle had been shaken and her head impacted against a wall or the floor.During her short relationship with Simpson, she voiced concerns that he might be a paedophile, and thought it was “weird” that he preferred to see her and Isabelle at the same time, rather than be alone with his girlfriend.But Walker did not break up with him, even though she was suspicious enough to check if he was on the Sex Offenders’ Register.Just 11 days before her fatal collapse, Isabelle was taken to her GP and then to hospital with a broken leg.Despite misgivings of some staff, the little girl was discharged to her mother who had shown aggression towards medics when concerns were raised about what had happened.Walker explained that Isabelle must have hurt her leg when it got caught in her cot.On that occasion too, Walker had waited two weeks to seek medical help for Isabelle, despite the toddler being in pain and struggling to walk.Richard Wright KC, prosecuting, told the court: “For weeks this child had been violently assaulted and her death, by that terrible head injury, was simply the end point in that campaign of violence to which she had been subjected.”The prosecution said both defendants had ample opportunity to harm Isabelle and the abuse would have been obvious to anyone who lived in the two-bedroom house.Videos taken last June – prior to Simpson coming into her life – showed the little girl happily playing, healthy and smiling.The couple had met on Facebook Dating earlier last summer and Simpson became a regular visitor to the house where Walker and Isabelle lived together.Walker had suffered from domestic violence previously and she had two cameras installed in her home, with one overlooking the back of the house that captured evidence reflected in a window.The camera showed how Walker was a frequent drinker, sometimes downing up to 10 cans of Stella Artois, and Simpson was a habitual cannabis smoker.The couple sold cannabis at times and Walker explained how bouts of self-harm which were caught on her CCTV were attempts to get out of selling drugs.The CCTV footage also proved that Isabelle suffered a broken leg while in the sole care of Simpson.Walker’s concerned mother said “looks like she is being abused” during one visit after Isabelle’s leg was broken.Simpson also bathed Isabelle without Walker’s permission while he supposedly looked after the two-year-old when her mother attended a hospital appointment.The night when Isabelle was fatally injured, the couple stayed up late, with Walker drinking cans of lager and Simpson smoking cannabis.The next morning Simpson got up – claiming to be looking after Isabelle – while Walker stayed in bed.In a horrific twist of fate one of the nurses who treated Isabelle’s broken leg – and who had concerns about her care – was on duty when she was brought back to University Hospital of North Tees, in a state of collapse 11 days later.Simpson and Walker were arrested after Isabelle’s death.Simpson declined to answer police questions and did not give evidence at the trial.Walker gave various accounts of what happened, eventually telling police she now believed her boyfriend had been abusing her daughter.Mr Wright said Walker did not protect her daughter, saying: “On the contrary, she delayed, she deflected, and she failed to act when action was most urgently required.”