A TODDLER was murdered by her mum and her boyfriend after a harrowing “campaign of violence” in which she sustained 21 broken bones, a court heard.

Isabelle Rose Welsh, two, suffered a catastrophic brain injury having suffered weeks of abuse at the hands of Alexandra Walker and Harrison Simpson, it is alleged.

The youngster endured multiple fractures to 21 bones in the days and weeks before her death on 14 September last year and had also been sexually assaulted, Teesside Crown Court was told.

Walker, 25, and Simpson, 22, deny murder, sexual assault, causing or allowing the death of a child and child cruelty offences.

Opening the case to jurors, Richard Wright, KC, prosecuting, said Isabelle had suffered a “campaign of violence” at her home in Hartington Close, Thornaby, where Simpson was a regular visitor.

The youngster died after allegedly being violently shaken and slammed against a “hard, unyielding” surface on September 13 last year before passing away in hospital in the early hours of the following morning.

Isabelle was returned to the care of her mum despite concerns being raised by health workers in the weeks before her death, the court heard.

She was admitted to hospital over a broken leg but two medical teams disagreed over how she got the injury and whether she was at risk.

She was then discharged and died eleven days later, the court heard.

Mr Wright said: “It seems that there were differences in opinion between the orthopaedic team and the paediatric team.

“As a result Isabelle was discharged back into the care of her mother.

“In a terrible twist of fate, one of the nurses who expressed the greatest concern about the leg injury would be working in the emergency department when Isabelle was re-admitted later having sustained her fatal head injury.”

Mr Wright said the health visitor phoned Walker on September 9 and added: “Without actually visiting Isabelle or checking on her welfare, the health visitor concluded the call and noted that she had no concerns.

“She could not have known that the fractured leg was just one of numerous broken bones that Isabelle had suffered, nor that she was days away from sustaining a fatal head injury.

“But then you may think that a telephone call was never likely to tell her any more than Walker wanted her to know.”

The court also heard that Walker had begun to have concerns about her new partner shortly after the relationship began.

She checked online whether he was on the sex offenders’ register – but continued the relationship regardless.

On August 20 she left Isabelle with him alone for the first time but when she returned she discovered her daughter had a knee injury, the court was told.

Walker ignored it for a fortnight before eventually being persuaded by her mum and stepfather to seek medical attention, the court heard.

Even when she agreed to do so she delayed it a day so she and Simpson could have “something of a party at home, drinking, smoking and taking drugs”.

Outlining the case, Mr Wright told how paramedics responding to a 999 call discovered Isabelle collapsed at the foot of the stairs covered in bruises, with “no pulse and plainly gravely ill.”

He said: “Isabelle’s death was not the result of some form of naturally occurring illness.

“She died because shortly before her terminal collapse somebody had inflicted a massive head injury upon her.

“Her skull had been fractured, her brain had been injured, and her heart had stopped as a result of that assault upon her.

Mr Wright added: “This was no accident. It was the deliberate infliction of injury on that little girl.

”It was, say the prosecution, murder.

“Neither was the assault on Isabelle an isolated act of violence towards her.’

Post-mortem tests on Isabelle revealed a catalogue of injuries, the jury was told.

She had suffered ‘multiple fractures to no less than 21 bones in her body’, including her arms, legs and spine, and 97 soft-tissue injuries.

The court heard that 11 days before Isabelle died, she was taken by Walker to see a GP who said her daughter was struggling to walk.

Walker reportedly claimed the toddler had trapped her leg in the bars of her cot two weeks earlier. At hospital, an X-ray revealed a spiral fracture of Isabelle’s right shin bone.

Mr Wright said: “Her right leg was found to be fractured, but despite the concerns of some of the medical staff, Isabelle was discharged back into the care of her mother, the account of an accidental injury seemingly having been accepted.

“That earlier fracture to her leg was however no more of an accident than the fatal head injury that killed her.”

Mr Wright said both Walker and Simpson “must have been aware” of the abuse because their two-bedroomed house was “so small and the injuries both so severe and obvious”.

He added: “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.

“Who had done this to Isabelle? The prosecution will invite you to conclude that Isabelle had been subjected to that violence by her mother and by her mother’s boyfriend.”

The prosecution alleged that Walker only called 999 on the day of her death after being told to do so by her stepfather “long after she must have known her daughter was critically ill.”

Mr Wright said: “Their failure to summon help from doctors and finally the emergency services was an act of self-preservation.

“They knew the questions that would come and had no convincing answer for them.”

The court heard that Simpson and Walker began a relationship in the summer of 2025. Isabelle, born in March 2023, was Walker’s only child.

Mr Wright said: “The prosecution say that there is no doubt that this relationship was unhealthy. That it was characterised by drink on the part of Walker and drugs on the part of Simpson.

‘”It led to a decline over time in the care that was being given to Isabelle.

“That then built into her being subjected to regular violence at home by these two defendants.”

Central to the six-week trial is CCTV footage taken from inside Walker’s home.