A foster carer has been sentenced to life imprisonment with a minimum term of 17 years after murdering a one-year-old child she was in the process of adopting.

Katie Tidmarsh was found guilty at Leicester Crown Court on Thursday of killing Ruby Thompson more than a decade ago after catastrophic brain damage led to her death in 2012.

On Friday, the 39-year-old was told by sentencing judge Mr Justice Mark Wall that her victim was a “defenceless young child” and her actions “constituted a gross breach of trust”.

The judge told Tidmarsh she was “ill-equipped” to raise a child due to her mental health difficulties, adding: “You also tried to cover up what you had done by delaying medical treatment for Ruby.”

Tidmarsh and her husband were in the process of adopting Ruby when a 999 call was made from the family address in August 2012 saying she had suffered a seizure and was not breathing. She died two days later.

The case took 11 years to come to court.

Referencing the delay, the judge told Tidmarsh: “The evidence is that you were able to get on with your life confident that your past would not catch up with you.

“This delay has allowed you to carry on with your life while relatively young for 10 years or more when you ought to have been in prison.”

Tidmarsh claimed Ruby was injured after her eyes rolled back and she fell onto a thick rug she was sitting on.

But medical experts proved the injury was caused by shaking and a high-energy impact.

Medics treating Ruby spotted two previous fractures to her right shoulder on her X-rays, as well as a broken arm which she was treated for two weeks before, with Tidmarsh saying the youngster had been knocked over by one of her dogs.

Tidmarsh, of Station Road, Littlethorpe, Leicester, was also charged with two counts of causing grievous bodily harm relating to previous arm break injuries to Ruby.

She was found guilty of one of these charges and not guilty of the other.

The judge told Tidmarsh: “You have always steadfastly maintained that nothing happened to Ruby on the morning of her collapse save that, as she sat on a rug in the living room, her eyes suddenly rolled into the back of her head and she fell backwards from her seated position onto the rug.

“The experts all agreed that this would not account for the injuries sustained by Ruby.

“Your story provided neither an explanation as to why her eyes might have rolled back into her head, nor an explanation for the other severe injuries.

“I sentence you on the basis that you abused her that morning and have lied to cover up what you did.”

He added: “Your victim was a defenceless young child and you, her carer.

“Your actions in respect of Ruby constituted a gross breach of trust.”

Mr Justice Wall described Tidmarsh as an “educated and intelligent woman”, but told her she had “always lied” about how Ruby had sustained injuries.

He said: “You only took her to hospital after your mother noticed that Ruby was in discomfort and not using her arm properly.”

Katie Tidmarsh was found guilty at Leicester Crown Court on Thursday of killing Ruby Thompson (Alamy/PA)

The judge told the defendant she had also lied about her mental health issues.

He said: “You deliberately covered up your mental health difficulties.

“Those actions gave the social workers confidence to entrust Ruby to your care.”

Tidmarsh’s conviction followed an inquest, and then lengthy court proceedings in 2017 when a judge ruled the foster carer had inflicted the injuries which resulted in Ruby’s collapse and death.

This prompted a further consultation between the police and the CPS and the instruction of extra medical experts.

Tidmarsh, who was previously arrested in 2012 before facing no further action, was arrested again in 2022 and charged with murder.