Psychopathology is the study of mental disorders. A good understanding of psychopathology allows law enforcement to understand psychopathy (not to be confused with psychopathology). Law enforcement must understand the psychopathic traits that make it easier for psychopathic serial murderers to evade capture by hiding in plain sight. They must also understand that psychopathy is not a mental illness, and therefore is not relevant to an insanity defense.
Most serial killers are not crazy lunatics. In fact, criminologists have found that many serial killers are often psychopaths. Psychopathy is not considered to be a mental illness (keep this in mind—it will be important later). Psychopaths are people who tend to lack empathy (the ability to understand how someone else feels), guilt, and respect for rules and laws—social and legal. Psychopaths are often charming and able to manipulate people. Psychopaths use their charm and manipulation skills to appear to others as if they have empathy and respect.
Psychopathy is diagnosed through a checklist developed by Dr. Robert Hare. Many serial murderers have large clusters of psychopathic traits. However, there is no profile of a serial murderer, and they are often influenced by social and environmental factors, as well.
According to the FBI:
The relationship between psychopathy and serial killers is particularly interesting. All psychopaths do not become serial murderers. Rather, serial murderers may possess some or many of the traits consistent with psychopathy. Psychopaths who commit serial murder do not value human life and are extremely callous in their interactions with their victims. This is particularly evident in sexually motivated serial killers who repeatedly target, stalk, assault, and kill without a sense of remorse. However, psychopathy alone does not explain the motivations of a serial killer.
Clearly, the ability to charm and manipulate can help serial murders lure their victims. Lacking empathy, guilt, and respect for rules makes it easy for the killer to justify his or her actions. What is important to understand from a law enforcement standpoint is that these are not just qualities that enable them to kill—they are qualities that enable them to fit in well with the general society so that they can keep on killing.
Serial murderers often live normal lives, with families, friends, and jobs. Often, they commit their crimes within their own communities. They tend to be below the radar of law enforcement. An extreme example of this is Ed Kemper, who began making friends with police officers while he was still killing. He actually called the police and confessed to the murder of his mother, but the police refused to believe him initially, thinking their friend was playing a joke.
According to the FBI, understanding psychopathology is important during the investigation phase of law enforcement, because sometimes victims are not well-known to the killer, making it difficult to establish motive in the standard fashion. Since psychopaths do not behave like “normal” people, “normal” profiling techniques may not work. Moreover, typical interview tactics do not work with psychopaths:
Psychopaths are not sensitive to altruistic interview themes, such as sympathy for their victims or remorse/guilt over their crimes. They do possess certain personality traits that can be exploited, particularly their inherent narcissism, selfishness, and vanity. Specific themes in past successful interviews of psychopathic serial killers focused on praising their intelligence, cleverness, and skill in evading capture (FBI).
It is important to note that psychopathy is not a motive—psychopathic serial killers always have a “reason” to kill—including money (such as “black widow” killers), power, even ideology (like racism).
According to the DSM-5 (the Diagnostic and Statistical Manual of Mental Disorders, the “official” list of all mental disorders), psychopathy is not a mental illness, like schizophrenia or depression. Therefore, most serial killers are considered to be mentally competent to stand trial, and insanity defenses are rare. In order to plead insanity, a defendant must prove that he or she did not know right from wrong at the time of the crime.
The topic of psychopathology is complex and broad. The FBI has a detailed analysis of serial murder, including a discussion about psychopathy and serial murderers, including specific examples of serial murders. Also check out these articles on serial murderer myths from Scientific American and the differences between sociopaths and psychopaths from Psychology Today.