The Homicidal Triad: Fact or Urban Legend?

Homicidal Triad

If you had to, do you think you would be able to spot a serial killer out of a group of twenty people? What about a group of ten people? What about if you had some background information on each of these individuals? Perhaps you found some who may have set fires at an early age, abused animals, and wet the bed often. Would this be enough to accuse the person of being a potential serial murderer?

Many professionals once thought that this was the case, and they called this the Homicidal Triad, or the Macdonald Triad. They believed that these behaviors seen in early childhood were indicative of someone who would grow up to kill. However, that might not always be true.

In the Past

The Homicidal Triad is such a popular theory that you are sure to have heard it before if you have even a passing interest in forensic psychology and crime. They often use these indicators in television dramas and novels as well, showing that there are things wrong with the killer from an early age and that if only someone had seen those signs and stopped him. However, those who could become homicidal and kill in serial fashion do not always show these tendencies, and those who do have those issues in the past do not always grow up to kill.

Charles Manson, while never convicted of murder, is one of the most notorious criminals in prison today, and one would think that he must also fit into this homicidal triad. However, he has more compassion for animals than he does for humans, and would scold other members of the Family and their associates if he ever saw them being cruel to an animal.

Researchers today are starting to see that, even though those indicators can show trouble in someoneâ??s life, they do not mean that he is going to be violent in the future. There is very little actual data that supports the Homicidal Triad theory.

Where Did the Theory Originate?

In 1963, Dr. John Macdonald described the triad for the first time in a paper published in the American Journal of Psychiatry. In a study of 100 patients who threatened to murder, those who were the most aggressive had histories of arson, animal abuse, and bedwetting. Over the years, it became almost dogma for those in the law enforcement community, as well as for many psychologists. Even Macdonald was not convinced of the accuracy of the Homicidal Triad, and he said as much in his book Homicidal Threats, which came out in 1968, five years after his initial study.

Many serial killers have at least one of the three indicators, but not all of them do. Thus, relying on this triad as a form of identifying potential serial killers is not only antiquated, it is dangerous. Arson and animal abuse are crimes in their own right, and should have appropriate punishments, but to guess that someone is going to become a murderer due to crimes as a child is a violation of good psychological practice. When a juvenile is found engaging in bad behavior, it is important to punish appropriately for that behavior, and to seek the proper counseling and treatment.

In Todayâ??s World

Today, those who get their degree in forensic psychology online or offline are not going to find much use for the Homicidal Triad. Other traits commonly found in killers seem to be more accurate, such as a disregard for othersâ?? feelings. This can be a sign of a sociopath, and while not all sociopaths kill, they all have a callous and emotionally detached feeling toward others. Watching this type of behavior is going to be far more beneficial than worrying about a bed wetter.

Anita Schepers provides advice and information on how to get a forensic psychology degree online at


Image courtesy of  Simon Howden /

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