Harrison Simpson, 22, and girlfriend Alexandra Walker, 26, were convicted of murder and child cruelty earlier this week.

18:58, Mon, Aug 3, 2026 Updated: 19:03, Mon, Aug 3, 2026

Harrison Simpson police mugshot

Harrison Simpson who along with Alexandra Walker murdered Isabelle (Image: Cleveland Police/PA Wire)

Police failed to arrest a violent offender despite a warrant being issued 18 months before he went on to murder and sexually assault his girlfriend’s two-year-old daughter. Isabelle Welsh endured weeks of horrific abuse before her death, suffering 21 broken bones before collapsing at her home in Thornaby, Teesside, in September.

Alexandra Walker, 26, and her boyfriend Harrison Simpson, 22, were convicted of murder and child cruelty earlier this week following a trial at Teesside Crown Court. Simpson was also convicted of sexually assaulting Isabelle, while her mother was cleared of that charge.

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Isabelle Rose Welsh death

Isabelle Welsh, 2 (Image: Cleveland Police/PA Wire)

Cleveland Police has admitted officers failed to execute a warrant issued by Teesside Magistrates’ Court for Simpson’s arrest in March 2024, 18 months before he killed the toddler, The Sunday Times reported.

The warrant was issued after Simpson failed to attend court for breaching a non-molestation order, an injunction designed to protect victims of domestic abuse.

It is understood the non-molestation order was imposed after reports that Simpson had harassed and threatened a woman.

The force said in a statement: “Multiple enquiries and arrest attempts were carried out to try to locate and arrest him, but these proved unsuccessful.”

It added: “We recognise the time Simpson had an outstanding arrest warrant is far from adequate.

Alexandra Walker mugshot

Alexandra Walker, Isabelle's mother (Image: Cleveland Police/PA Wire)

“A review of this was immediately conducted upon his arrest for murder.

“This review, along with a determination to continually improve our processes around suspect management, has led to a number of recent changes, such as ongoing improved visibility across the force around outstanding warrants, a comprehensive data system which tracks all outstanding warrants, and stringent oversight including a governance group led by a superintendent.”

Mrs Justice Norton said Isabelle’s murder was the final act in a sustained campaign of violence, which the pair then attempted to cover up.

She jailed them for life with minimum terms of 28 years and six months for Simpson and 22 years for Walker, both minus time spent on remand.

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Prosecutor Paul Abrahams told the court: “This was a campaign of quite deliberate extreme violence.”

Mrs Justice Norton said: “Any death is a tragedy. The death of a very young child at the hands of those who should have cared for, protected and loved her – as she no doubt loved them – is particularly distressing for all involved.”

She said the toddler sustained an unsurvivable head injury in the 24 hours before she died in hospital.

The girl was sexually assaulted around the time the fatal blow was inflicted, the judge said.