Causes of Crime

As late as the 1950s researchers continued to investigate the relationship of body types to delinquency and crime. Aside from biological traits indicating a natural tendency toward criminal activity by some individuals, Lombroso and other early twentieth century researchers also reasoned that criminal behavior could be a direct result of psychological disorders. They believed these mental disorders could be diagnosed and possibly cured. If this was true, then criminal activity could be considered a disease and the offender could be "cured" through psychiatric treatment. Research by Lombroso and others also led to the use of expert medical witnesses in the courtroom during criminal trials.

In 1941 American psychiatrist Herve Cleckley (1903–1984) used the term psychopathy, or sociopathy, in the book The Mask of Sanity to describe a form of mental illness. People showing sociopathic traits were antisocial, often destructive, and showed little emotion. Such personality disturbances, he believed, could lead to criminal behavior.