An 8-year-old boy accused of beating a 1-year-old girl to death while they were left home alone as their mothers went to a night club has been charged with murder.

Police say the child, Kelci Lewis, died from severe head traume and major internal organ damage. She was beaten to death because she wouldn't stop crying, police said.

The baby's mother, 26-year-old Katerra Lewis, was charged with manslaughter and released on a $15,000 bond. The boy's case will go through the family court system, police said.

Birmingham Police Department spokesman Lt. Sean Edwards told WBRC in Birmingham that investigators are struggling to understand how an 8-year-old child could have "that much evil in his heart" to kill the little girl.

“The 8-year-old just recklessly, viciously dealt with the 1-year-old," he said.

He said the boy will need “extreme intervention” and "intense counseling for the next several years,” according to the Washington Post.

There's no minimum age for prosecution in Alabama.

A director at the Southern Juvenile Defender Center says she believes there will be questions on whether the boy has "the rational capacity for the proceedings against him."

A vigil was held in honor of the 1-year-old Tuesday.