Cleveland Police failed to detain a man for 18 months after a warrant was issued for his arrest, during which time he murdered his girlfriend's two-year old daughter, it has emerged.
Isabelle Welsh endured a "sadistic" campaign of violent abuse before being murdered at her Thornaby home in September by her mother and new boyfriend Harrison Simpson, who was jailed for life in July.
It has now emerged that after he failed to attend court for breaching a non-molestation order, a warrant was issued in March 2024, but attempts to locate him were unsuccessful.
The force said it immediately carried out a review and has since made a number of changes, including reviewing all outstanding warrants.
The murder trial at Teesside Crown Court heard that Isabelle Welsh was a "happy and thriving" child before her mother, Alexandra Walker, invited Simpson into their lives in June 2025.
On the morning of 13 September she was found fatally injured with Walker not calling 999 until hours later.
It was found she had suffered a fractured skull and an "unsurvivable" brain injury.
It could not be said who inflicted the fatal injury, the court heard, but Walker claimed she was sleeping in after a drink and drugs binge at the time and only found Isabelle injured in her cot later.
Simpson, 22, and Walker, 26, were both found guilty of murder and child cruelty, with Simpson also convicted of sexual abuse of a child.
Both were jailed for life with Simpson ordered to serve a minimum of 28 and a half years and Walker 22 years.
Cleveland Police has now admitted after Simpson was issued with a warrant for failing to attend court on a charge of breaching a non-molestation order - an injunction designed to protect victims of domestic abuse - multiple enquiries were carried out to try to locate and arrest him but without success.
Isabelle's family had been informed of the circumstances early on in the investigation, it said.
The statement added: "We recognise the time Simpson had an outstanding arrest warrant is far from adequate.
"A review of this was immediately conducted upon his arrest for murder."
It said the review had led to a number of recent changes, such as "a comprehensive data system" which tracked all outstanding warrants, and stringent oversight including a governance group led by a superintendent.
The force added: "Those outstanding warrants posing the highest risk are reviewed daily by senior management."
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