Low MAOA has been linked to reduced volume in the amygdala the emotional center of the brain while physical child abuse can damage the frontal part of the brain, resulting in a double hit.

WSJ: Neurocriminology: Inside the Criminal Mind

"We are talking about child abuse, physical abuse, mental abuse, actually using emotional abuse against the child - quite serious offences in some cases - up to physical woundings of children, " Mr Bourlet said.

BBC: NEWS | UK | Call for action on child exorcism

The state agency is brought in when there is suspicion of physical, mental, or emotional abuse of a child, according to Brockton police Lt.

CNN: STORY HIGHLIGHTS

Texas Child Protection Services confirmed it had received allegations of physical abuse and neglect and was investigating, but had not yet determined whether the allegations were true.

BBC: Russia investigates 'murder' of Max Shatto, US adoptee

As his files documented, as a child he suffered from poor nutrition, severe parental neglect, sustained physical and sexual abuse, early head injuries, learning disabilities, poor cognitive functioning and lead exposure.

WSJ: Neurocriminology: Inside the Criminal Mind