A mother jailed for murdering her seven-month-old baby had confessed to attacking another child years earlier.

Last year, Jennifer Crichton, 35, fatally attacked her daughter Amelia while under a social service care plan outsourced to a local social care provider.

Crichton, of Leyland, Lancashire, had been arrested by police but never charged after seriously injuring another child, but went on to admit that earlier attack to a social worker, a nurse and a doctor.

It was only after she inflicted “catastrophic” and fatal head injuries on Amelia that she was prosecuted for the earlier offences.

A serious case review is under way involving police and social services.

On Tuesday, Crichton was convicted of Amelia’s murder at Preston crown court after a five-week trial.

She was also convicted of three counts of grievous bodily harm with intent and child cruelty relating to the victim of the earlier attack, who cannot be named for legal reasons.

On the night Amelia was fatally attacked, Crichton had been asked by her social worker to take over feeding her daughter, but replied: “No, you do it,” and went for a cigarette instead.

Later the same evening, the social worker left Crichton alone with the baby at her home and within two hours the mother had inflicted “catastrophic” head injuries on her “helpless and vulnerable” child.

Amelia was born more than three months early and had to spend her first six months in intensive care owing to her prematurity.

She died in hospital two days after the attack on 19 April 2017.

Crichton tried to blame her partner, Richard Sheppard, for the injuries.

She told a social worker “I’m a good mother”, but was also “loud and aggressive” and heard to shout at her child: “Go to fucking sleep” or “Do not piss me off”, the court was told.

Despite weighing just 1lb 4oz (570g) when she was born on 8 September 2016, Amelia behaved like a normal baby, going home to live with the defendant under a “care plan” with the help of support workers who stayed overnight at the address until the hours were reduced over time, the jury heard.

At around 6pm on the night Amelia was fatally attacked, a care support worker arrived at Crichton’s home.

At 11pm the care worker left and Amelia appeared to be fine, until, an hour and 20 minutes later, Crichton rang 999 for an ambulance reporting that her daughter was not breathing.

Amelia’s injuries included severe bleeding on the brain, in her right eye and a complex skull fracture, as well as with internal bleeding along the length of her spine.

Crichton offered no explanation for her daughter’s injuries, other than to say she had “collapsed”, even as doctors tried to save the child’s life.

Expert medical examination concluded Amelia had been the subject of a “violent physical assault” as a result of “striking or throwing” against a hard surface as well as bodily shaking.

Outside court, DI Simon Cheyte, of Lancashire police, said: “In relation to the conviction for assault on the other child, this was subject to a previous police investigation and Jennifer Crichton was arrested but at that time it was decided by the Crown Prosecution Service there was not enough evidence to prosecute her.

“Following the murder of Amelia, the earlier assault was reviewed and further evidence, not available to the original investigation team, was discovered.

“This was considered along with the supporting evidence of Amelia’s sad death and it was decided that charges could be brought and today’s conviction secured.”