A 17-year-old who killed his girlfriend's "at-risk" baby with a blow to the head has been sentenced to life in detention.

Mitchell Cooper, 17, of Great Yarmouth, Norfolk, was detained for a minimum of 12 years after being found guilty of murdering 11-month-old Ruby Spink following a trial at Norwich Crown Court.

Baby Ruby was killed six days after a social services department placed her on an at-risk register. The court heard the little girl's ribs and legs had also been broken.

The jury was told Cooper had told paramedics that Ruby had choked on a piece of cake.

She had lived at a hostel in the town with her mother, Laura Spink, 18, who pleaded guilty to neglect and was sent to a young offenders' institute for a minimum of 12 months.

Spink had covered for Cooper and despite advice to the contrary, had allowed him unsupervised access to her child, who she had in a previous relationship.

Judge Jacobs decided it was in the public interest for Cooper's identity to be published and lifted reported restrictions, describing the teenager's actions as "cynical".

The judge said: "You just lost it. You resented the child. Your dislike of the child came to the surface. You forcibly banged this child's head... against a hard surface.

"As a result of that, you caused a fracture to the skull, which resulted in death, probably instantly. Then you covered it up. There was something almost cynical about the way you tried to cover it up."

Following the case, it emerged social workers were "closely monitoring" Ruby's welfare after being alerted to her plight less than two months before she died last September.

Ruby was also said to have been examined by a GP and two specialists in the weeks before her death. All were said to have noted injuries but all thought she had been hurt accidentally.

Sentencing Spink, Judge Jacobs said: "You told all sorts of lies, some of them absurd lies."

To the couple he said: "You're both insecure, you're both irresponsible. You're both the victims of a cycle of depravation, but there's nothing in your background which justifies the way you treated this child."

Elsewhere, Mark Howe, 36, of Wallington, Surrey, was found guilty of manslaughter after killing his baby daughter in a fit of temper while looking after her on her mother's first night out since giving birth.

The former supermarket manager punched, kicked or stamped on the little girl's stomach with such force that he tore her gut, leaving her slowly dying.

The child's devoted mother had previously never been apart from her for more than an hour in the 18 months since she was born. Jurors heard that she was "overprotective" because she and Howe had earlier lost a son who was stillborn.

Howe, who spent part of the evening smoking cannabis and drinking, struck the baby with a "severe blow" that ruptured part of her small intestine.

The mother did not realise how ill her daughter was until the next day. By then the baby was floppy and starting to turn blue, but Howe tried to stop her from calling an ambulance, in a bid to cover up his attack, saying: "I don't want to lose you."

When she ran off to get help, Howe drove off with the toddler and was later found by police sitting outside a hospital with her. Medics did their best to save the little girl but she was probably already dead - although she might have lived if doctors had seen her earlier.

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