Crimes and Mental Illnesses: What Are Connections?

People with mental illnesses are hard to be conscious of their actions, and consequently, they may be engaged in criminality more often. When examining criminal acts, investigators tend to pay attention to the external details of the offense, whereas the internal state of offenders is often considered unimportant. The one was engaged in a crime, and it is usually enough to regard them guilty; however, their mental state may be essential to understand the extent of their guilt.

One of the examples is psychopathy: criminal behavior is typical for people with antisocial personality disorder (APD), as may be concluded from its name. People with this disorder tend to have behavioral patterns destructive to others. One of the cases is the situation with J.W. Gacy, who committed rapes and murders of teenage boys (Weaver & Meyer, 2019). He did not confess his crimes, as psychopaths have no remorse and are experts in lying and concealing their wrong deeds. Even after imprisonment, he simulated good behavior, being able to leave the prison as soon as possible and commit his crimes again. In that way, one should be much more careful with people who are diagnosed as psychopaths: they are more prone to conduct crimes and are good at concealing them.

Another case is delusional disorder and the complex states connected with it, such as deep depression and losing control: people often hear voices in their heads that command them to do evil deeds. For example, a longshoreman William Davidson, 56 years old, shot his foreman a day after their hassle (Melton et al., 2017). He had experienced visions for 20 years where he saw devils performing sexual acts, which became traumatic for his mental health. A year before the murder, Davidson became concerned about losing his sexual power, and his mental health started to worsen even more. The hassle begins because the foreman tells Davidson that he is drunk and should leave home, but he hears abuses connected with his sexual problems, being in hallucinations. One can conclude that people with delusions may be inclined to unintended criminal activity and should receive special treatment to prevent it.

Lastly, mental retardation can also be connected with crimes, as people who cannot think clearly and consciously may conduct crimes when in a bad emotional state. An example is the case of Johny Paul Pendry, who was sentenced to the death penalty by a Texas court for capital murder. He suffered from severe mental retardation and was heavily traumatized in childhood: thus, his emotional state was hard and broken (Weaver & Meyer, 2019). Unlike a person with psychopathy, such as Gacy, who is intended to make people harm due to his mental condition, Pendry is not intended to do it. Thus, capital punishment is a cruel penalty for him, considering that the Texas court eventually renounced the punishment, replacing it with imprisonment.

Based on those three cases, I would say that mental states in general, and illness in particular, are essential for a person’s criminal background. It would clarify the conditions in which a crime was conducted, enabling an understanding of how to prevent them in the future. It would also allow one to see what to expect from the offender in the future because various psychological states make people act differently.

Thus, crimes and mental issues are heavily interconnected, and one would better not forget about those connections. An offender with psychopathy behaves profoundly differently from one with delusions, and both are distinctive from those with mental retardation. All three cases would be very different from those where people have no pathological neurophysiological conditions or try to simulate them. In that way, the mental states of offenders should be considered significant, as they may tell how to deal with each offender.


Melton, G. B., Petrila, J., Poythress, N. G., Slobogin, C., Otto, R. K., Mossman, D., & Condie, L. O. (2017). Psychological evaluations for the courts (4th ed.). The Guilford Press.

Weaver, C. M., & Meyer, R. G. (2019). Law and mental health: A case-based approach (2nd ed.). The Guilford Press.

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LawBirdie. (2023) 'Crimes and Mental Illnesses: What Are Connections'. 31 March.


LawBirdie. 2023. "Crimes and Mental Illnesses: What Are Connections?" March 31, 2023.

1. LawBirdie. "Crimes and Mental Illnesses: What Are Connections?" March 31, 2023.


LawBirdie. "Crimes and Mental Illnesses: What Are Connections?" March 31, 2023.