ABC News Scientist Related to Killers Learns He Has a Psychopath’s Brain Northeastern University criminologist Jack Levin agrees environmental influences determine whether a psychopath will go on to be violent, but discredits Fallon’s theory The author of a book about mass murderers, “Extreme Killing,” Levin said most serial killers are in their 30s and 40s. “You can determine the biological roots of psychopathy, including the lack of […]