Scientists trying get inside the minds of serial killers and mass murderers have found the combination of mental health issues from autism to head injuries with psychological trauma can lead to violent crimes.
The study at the University of Glasgow is the first of its kind and identified a complex relationship between neurodevelopmental problems and psychosocial factors.
It found that 28 per cent of multiple killers were believed to suffer from autism spectrum disorder (ASD) and 21 per cent had suffered a definite or suspected head injury in the past.
Of those killers with ASD or a head injury, 55 per cent had experienced traumatic events that caused psychological stress.
The lead researcher, Dr Clare Allely, from the Institute of Health and Wellbeing at the university, said: “It is crucial to note that we are not trying to suggest that individuals with ASD or previous head trauma are more likely to be serial killers or commit serious crime.
“Rather, we are suggesting that there may be a subgroup of individuals within these groups who may be more likely to commit serious crimes when exposed to certain psychosocial stressors.”
The findings, published in the Journal of Violent and Aggressive Behaviour, show a relationship between neurodevelopmental disorders, such as ASD or head trauma, and psychosocial disorders, such as exposure to physical or sexual abuse during childhood.
Dr Allely said research on mass and serial killing is “very much in its infancy” and more study is needed to understand the mechanisms underlying extreme forms of violence so prevention strategies can be developed.
She added: “We would recommend that in future, all serial or mass killers who are apprehended should be thoroughly assessed using standardised tools for investigating neurodevelopmental disorders.”
Mass murder is usually defined as killing several people in a short space of time, typically in one event, whereas serial killers may murder people over long periods.
Carol Povey, director of the National Autistic Society’s Centre for Autism, said: "This is a very serious issue and research like this is vital if we are to develop preventive strategies.
“But we would urge people not to jump to conclusions about people with autism and to make judgements about a whole section of society.
“This and previous research shows that the vast majority of individuals with autism are law abiding and respect the rules of society. Indeed, in many cases, individuals with autism are unusually concerned to keep the letter of the law, due to the nature of the disability.
“This research reaffirms the importance of ensuring that people with autism get the support they need as early as possible.”