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  • Writer's pictureAndrea Cipriano

Macdonald Triad: Can 3 Behaviors Predict Who Will be a Killer? 

Psychologists and criminologists have been trying for decades to uncover any behavioral secrets that would help predict if someone would become a future predator. 

The belief was that if you could catch someone while they were still young before they reached peak criminality, you could stop their devolution into brutality through therapy, treatment, and rehabilitation. 

But, if the psychologists and police couldn’t identify the warning signs fast enough, something terrible might happen, and the rehabilitation would be traded for criminal punishment.

One psychiatrist, John Macdonald, tried his hand at discovering behavioral predictors of criminality. In 1963, he published a paper in the American Journal of Psychiatry, titled "The Threat to Kill," where Macdonald claimed he had discovered the 3 youth-behavioral keys that warned of a violent future. 

Macdonald said that if a child older than five years old continually wets their bed (enuresis), starts fires, or abuses animals, then that child would grow up to become a violent killer. 

These behaviors quickly became known as the Macdonald “Homicidality” Triad. 

But, is his theory accurate? 

Let’s look at the sheet.

Understanding the 3 Behaviors

After Macdonald singled out these three behaviors and labeled them as the “main predictors of serial violent behavior,” psychologists and criminologists worked tirelessly to understand the phenomenon. 

Bedwetting (enuresis) that occurred continuously after a child turned five was a sign that the child was chronically stressed or anxious. However, the resulting bedwetting would in turn make the child feel embarrassed and like they’re in trouble. This would fuel feelings of self-hatred and aggression, according to Macdonald’s paper. 

Fire-Starting behaviors are said to be a physical manifestation of internal anger. Macdonald argued that this low-level arson would be brought out by a child that feels like they have no control over something in their life.

I believe it’s much like how once a fire is started, there is no control over what it might damage unless it’s put out, and some children have an unconscious connection to that feeling of being destructively out of control.  

Animal Cruelty is arguably the most disturbing and potentially valid behavior in Macdonald’s Triad. Abuse towards animals is said to come about when the person inflicting the pain has been humiliated or hurt, and now they’re taking those feelings out on something more defenseless. 

It’s about gaining power back that they feel they’ve lost. 

Animal cruelty is also said to be "practice" for a much larger victim — like another person. The act of moving from a low-risk victim to one with more risk is considered "graduating," so the idea of adding this into the Triad is about catching the initial behavior before it potentially turns into something more sinister.

All of these behaviors put together surely paint a horrible and evil image of a child, but is it true that these can definitively predict if someone will become a violent adult the way Macdonald thought? 

Well, the answer is — yes and no. I know, it’s not the answer you were hoping for, but it’s the truth.

So, what does the research say?

When looked at for face value, the theory seems to make sense. Young expressions of violence, aggression, destruction, and damaged emotions ... is this not a real cocktail for someone to lash out? 

In many ways, it is — but Kori Ryan, PsyD, an assistant professor of behavioral sciences at Fitchburg State University who has studied the Macdonald Triad extensively, says the original research “became an academic game of telephone.”

Macdonald originally developed his theory with 5 behaviors: "a history of great parental brutality, extreme maternal seduction, childhood firesetting, cruelty to animals and enuresis." But, over the years following his "Threat to Kill" publication, the theory dwindled down to the latter three.

Macdonald's theory was born in the 1960s after interviewing 100 patients at the Colorado Psychopathic Hospital in Denver, Co., where all of the patients had threatened — but not necessarily committed — violence as an adult, according to his paper. So clearly, this is a homogeneous small sample.

Then, in 1966, the Macdonald Triad theory was somewhat replicated when a study led by psychiatrists Daniel Hellman and Nathan Blackman examined 88 violent criminals and found every person fulfilled the Triad in part — but only 31 exhibited every behavior as a child. 

However, multiple academic attempts made over decades to replicate Macdonald’s (1963) and Hellman and Beckman (1966) original findings in different samples of criminals were unsuccessful. 

In a 1984 study conducted by psychologists Robert A. Prentky and Daniel L. Carter aimed to address the Triad with a population of 206 sex offenders from the Massachusetts Treatment Center for Sexual Dangerous Persons, the psychologists found "no compelling evidence" to support that all three behaviors were exhibited by the criminals during childhood.

They did, however, conclude any exhibited behaviors from “the triad appeared to be primarily a maladaptive response to the turmoil and abuse in the home prior to and during adolescence,” according to their report.

In a more modern study of 45 male prison inmates who were considered violent offenders, professor and psychologist Dr. Janet McClellan (2003) found that 56% admitted to having committed acts of violence against animals at some point in their life.

While 56% of 45 engaging in animal cruelty is uncomfortably high, it’s not enough to support everything Macdonald originally claimed. 

Dr. Katherine Ramsland, a renowned forensic psychologist who worked one-on-one with Dennis Rader, the BTK Killer, wrote of the theory,Although some violent offenders do have excessive fire-setting, animal cruelty, or bedwetting past age five in their backgrounds, rarely do all three behaviors show up.”   

So, when put to the test through research and study, it’s impossible to make a definitive conclusion — even John Macdonald himself later stepped away from using his Triad in a psychiatric setting.

Despite the controversial academic results, there seems to be some anecdotal evidence that supports the theory — at least in part.

Robert Thompson and Jon Venables, the 10-year-olds who abducted and killed 2-year-old James Bulger, both exhibited animal cruelty when they were younger. The duo would shoot pigeons with air rifles and tie rabbits to train tracks, and wait and watch until they were run over, according to the Independent.

David Berkowitz, the "Son of Sam" killer began torturing animals at the age of 10, and he was so infatuated with fires as a child that his friends nicknamed him "Pyro," according to the Crime Museum in Tennessee.

This small anecdotal list could continue for pages, but until the Triad's theory is also confirmed through an empirical research standard, it's just that — anecdotal information.

Consequences of the Theory

Anything that claims to “predict” future homicidal behavior should be studied by forensic psychologists and criminologists, but it must be analyzed thoroughly and carefully. If an uneducated and biased conclusion is made, it can have real consequences for troubled youth. 

You can also run into the issue of confirmation bias, where if a young person is confronted with their behaviors by a police officer or a therapist who has knowledge of the Macdonald Triad, they could falsely and prematurely label an individual as a future sex offender or serial killer. 

I mean, talk about damaging someone’s already-damaged-psyche, right? 

Too often in the true crime community, I see serial killers' previous behaviors discussed in absolutes, rooted with the intention of better understanding and learning, but ultimately it results in a pigeon-holed belief of what criminality looks like without looking at the context or co-occurring behavior.  

But what if a child IS exhibiting these behaviors? 

If a child is experiencing enuresis while engaging in animal cruelty and fire-starting, these are more like red flags and warning signs that signify something else is going on — it doesn’t mean that a child is destined to become a serial killer. 

More likely, the Macdonald Triad traits indicate that the child is going through something incredibly stressful in their life, like sexual or physical abuse, or severe bullying. They may also feel like they have no control over their life, and that they don’t have the ability to express their feelings.

If we unpack the three behaviors that Macdonald originally detailed, and narrow them down to feelings of wanting power as a result of humiliation (animal cruelty), venting aggression (fire-starting), and dealing with fear and anxiety (bedwetting) — we can identify the root causes that drive these behaviors. 

Once that’s identified, treatment options and resolutions can be discussed. 

There is high-quality research that proves at least two of the behaviors —fire-starting and animal cruelty— are behavioral symptoms that indicate a child has a developmental disability or that they’re developing an impulse control disorder or conduct disorder.

It’s important to look at the full picture — to take a step back and analyze the totality of someone’s character with an emphasis on their biological, developmental, and situational factors that can influence behavior. 

Just as Kori Ryan, a Macdonald Triad expert has said, “all behavior is on a spectrum.”

Overall, there are no easy answers to predicting if a child or young adult will become a thing of nightmares. The Triad shouldn’t be discounted, but it shouldn’t be an absolute either.

If anything, the Macdonald Triad teaches us to keep an eye out for our children and to assess their behavioral and emotional needs as they arise. 


There are a multitude of resources if you know a child experiencing any of these behaviors who needs help: 

Disclaimer: This article is not to discount warning signs of abuse or aggressive, violent, compulsive behavior. Instead, this piece is to open the discussion between what is known and what is not known in the profiling criminology world as it relates to predictive behavior.

Moreover, this piece is written from the perspective of addressing children’s behavior — not that of a grown adult.


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