Miami: An eight-year-old boy beat a baby girl to death to stop her crying while her mother was out partying at a nightclub, US police said Wednesday, charging him with murder.

The boy was one of several children left alone for hours in a Birmingham, Alabama home last month, in what experts said was a rare case of a child so young being prosecuted.

‘Since becoming a police officer over 22 years ago, this is by far one of the saddest cases I have witnessed in my career,’ Birmingham police spokesman Lieutenant Sean Edwards told AFP.

The incident happened at the home of a friend of the baby’s mother, whom police have identified as 26-year-old Katerra Lewis.

She has been charged with manslaughter over what Edwards called ‘reckless’ actions.

Police said Lewis left her one-year-old, Kelci, together with several children aged two to eight, while she and her friend went out clubbing.

The children — six in total, according to local media — were left unsupervised while Lewis and the friend were gone from roughly 11:00 pm until 2:00 midnight.

‘It is believed that while the mother and friend were at the club, the eight-year-old viciously attacked the one-year-old because the one-year-old would not stop crying,’ police said in a statement.

‘The one-year-old suffered from severe head trauma as well as major internal organ damage which ultimately led to her death.’

The mother told police on the morning of 11 October, a Sunday, that she found the baby unresponsive in her crib.

The girl was treated at the scene by first responders and was later pronounced dead at a children’s hospital.

‘This type of behavior, this type of irresponsibility on behalf of a parent is totally unacceptable,’ Edwards said of Lewis.

‘No education, no school, no degree, no training can really prepare you for an eight-year-old committing a heinous crime like this.’

The mother was released on $15,000 bail. The Department of Human Resources said it had no prior complaints concerning Lewis or her daughter.

The DHR is holding the boy and won’t release his name.

‘Very, very unusual’

The age at which minors can be held criminally accountable varies from state to state in the US, but Alabama has no set minimum age for prosecution in juvenile court.

‘It is very, very unusual for somebody as young as eight to be prosecuted,’ Tobie Smith, a lawyer who specializes in the defense of minors in Alabama, told AFP.

The boy will be tried in juvenile court and risks being sentenced to juvenile prison until up to age 21 if found guilty, Smith said.

However, prosecutors must demonstrate that the boy is competent to stand trial and participate in his own defense, Smith said.

‘That requires a level of intellectual development and coordinative functioning that is less and less common the younger you go.’

Prosecutors could also technically file for the boy to be tried as an adult under Alabama law, although it is extremely unlikely that they would do so.

‘I would be stunned and shocked and appalled if they did and I also cannot imagine that the judge would transfer him to an adult court if they asked,’ said Smith.

Last month, an 11-year-old boy from Tennessee was charged with first degree murder after he shot and killed his eight-year-old neighbor following an argument over a puppy.