New research sheds light on the psychological profiles of individuals who have been convicted of capital murder in California and sentenced to death. The study, published in the Journal of Forensic Sciences, found a “pronounced heterogeneity” concerning clinical psychopathy. While a substantial proportion of the offenders exhibited heightened psychopathic features, others showed no signs of psychopathy.
Psychopathy is considered important to understanding criminal behavior because it is a personality disorder characterized by a lack of empathy and remorse, along with impulsive and reckless behavior. Research has shown that individuals with psychopathic traits are overrepresented among offenders, particularly those who have committed violent or repeat offenses.
Understanding the characteristics and behaviors associated with psychopathy can aid in the prediction and prevention of criminal behavior, as well as the development of more effective treatment and rehabilitation programs for offenders.
“Psychopathy and homicide offending are two of my areas of research, so the current study combines those using a very unique data source,” said study author Matthew J. Delisi, a distinguished professor, dean’s professor, and coordinator of criminal justice at Iowa State University.
For their study, the researchers examined data from the Death Row Tracking System maintained by the California Department of Corrections and Rehabilitation Division of Adult Operations. The sample included 636 individuals convicted of capital murder and sentenced to death. The data included information on the offender’s psychopathology, personality functioning, offending history, and criminal justice system involvement.
“The data took three years to collect,” noted Delisi, the author of “Ted Bundy and The Unsolved Murder Epidemic: The Dark Figure of Crime.”
The offenders exhibited many aggravating circumstances related to their murder cases, such as kidnapping, rape/sexual assault, armed robbery, and torture. The most common manner of death was shooting with firearms, followed by stabbing with bladed weapons, and manual strangulation. The sample was racially and ethnically diverse (38% African American, 36% white, 24% Hispanic, and 2% Asian or Native American) but overwhelmingly male (97.3%).
The researchers used the Hare Psychopathy Checklist-Revised (PCL-R) to assess psychopathy. It is a 20-item questionnaire that is administered by trained professionals and scored based on a subject’s file information and an interview. The items on the checklist are designed to measure the presence of certain personality traits and behaviors that are associated with psychopathy, such as a lack of remorse, manipulativeness, and impulsivity.
PCL-R scores range from 0 to 40. A score of 30 or greater corresponds to a diagnosis of psychopathy. For the current study, the researchers scored offenders based on information in their legal documents, as conducting an interview was not feasible.
Delisi and his colleagues found a surprising level of heterogeneity. The average PCL-R score of the sample was 23.31, indicating that the “average murderer on death row in California is moderately psychopathic,” Delisi told PsyPost.
But nearly 15% of the sample had PCL-R total scores under 10. “Some of these offenders had no official criminal history prior to their capital crimes, were contrite, apologetic, and remorseful during their court proceedings, and generally engaged in normative conduct,” the researchers said.
On the other hand, one-third of the offenders met the diagnostic threshold for clinical psychopathy. “To put this into perspective, <1% of those in the general population meet diagnostic thresholds for clinical psychopathy, and the majority of the general population does not exhibit a single psychopathic trait,” the researchers explained. Clinical psychopathy is over 50 times more prevalent among these individuals convicted of capital murder and sentenced to death relative to studies of individuals in the general population.”
“There is lots of diversity in psychological functioning among death row inmates,” Delisi explained. “Some do not have a single feature of psychopathy, others are complete psychopaths.”
The researchers also found that psychopathy was associated with several other psychiatric conditions. Highly psychopathic offenders were much more likely to also exhibit signs of Conduct Disorder and Antisocial Personality Disorder and slightly more likely to exhibit signs of ADHD, Oppositional Defiant Disorder, and sexual sadism compared to their less psychopathic counterparts.
“More psychopathic murderers had more severe psychopathology,” Delisi said.
Psychopathy was also positively related to number of arrest, prison sentences, and arrest onset age, demonstrating that the condition “is tightly bound to criminal career severity.” In other words, psychopathic offenders “had earlier starting and more extensive criminal careers,” Delisi explained.
The study, “Psychopathy among condemned capital murderers“, was authored by Matt DeLisi, David J. Peters, Andy Hochstetler, H. Daniel Butler, and Michael G. Vaughn.