The Killer Is Not a Monster. He Is the Proof That None Has to Exist.

What a former FBI profiler taught me in one long conversation about killing, what neuroscience does with it, and why 668 people die here when more than 16,000 die there

About 2 weeks ago I spoke with a man who spent most of his working life looking inside the heads of people who had killed other people. For decades he was a profiler with the FBI. Today he is retired, in the formal sense, because the kind of man he is does not retire. He still consults privately, on big cases, in New York, where the files are thick and the pictures are bad. The conversation ran for hours, and I did what I always do when a person sits across from me who knows something I do not know. I listened, I asked, and I soaked up every word the way a dry sponge soaks up water.

Anyone who knows me knows this about me. Knowledge that is handed to me, by someone who truly has it, not secondhand, not from a podcast, but from thirty years at the scene, is the most valuable thing a person can give me. I become grateful in an almost uncomfortable way. And I forget none of it.

What fascinated me most about this man was not what he told me about individual cases. It was a particular trait he mentioned in passing, as if it were the most natural thing in the world. He said he had often had a feeling, early on, about how to classify an offender. A gut feeling. A hunch that was there before the reasoning was there. And in most cases he turned out to be right.

I am a scientist. My first reflex at the word gut feeling is mistrust. My second reflex is the question: what is that, actually, in neurological terms? Is it magic, is it experience, is it a man who overrates himself and counts his hits while forgetting his misses? That exact question would not let go of me after the conversation. I sat down and read for weeks, every study I could find on the subject, and I checked whether what he had told me holds up. Some of it held up. Some of it held up with startling precision. And some of it was exactly that pretty myth television has been selling for decades.

This article is the result. It is neither medical nor legal advice, it is the most honest account I can give of a question that has accompanied me for over 20 years, in every case I ever worked on.

The Question I Asked Myself at Every Crime Scene

I spent a large part of my life as a court-appointed forensic expert. Sexual offences, violent crime, murder, manslaughter, attempted manslaughter. I sat over the files, I sat in the courtroom, and I sat, again and again, in front of images and videos that a normal person never has to see and never wants to see.

And I looked at the offender. Every single time. I looked into that face and asked myself the same question I could never fully answer: was it him? Can this person sitting here really be that brutal? How does it work? How can a human being lose control so completely that he drives a knife into another body more than 20 times? Not once, not twice in the heat of the moment, but 20 times, 25 times, far past the point where the victim has long been dead.

The uncomfortable answer is: it works. It happens. And it happens more often than most people are willing to bear.

I work differently from many of my colleagues, and I have described this once before elsewhere. On every assignment the file interested me almost not at all, at first. For me the essential material was always the images and the video. The trace itself, not the story someone else had already written about it. Only at the very end, when my report was essentially finished, did I read the file. Deliberately last, in order to rule out, with all the force I had, the one thing a forensic expert must never permit himself: bias. The preconceived opinion. The thought that nests itself before you have looked for yourself, and that then colours everything that comes after. Whoever reads the file first sees in the image only what the file told him to see. Whoever reads the image first sees the image.

Then I proofread the expert report one final time, and the matter took its course up to trial. And yes, it is a strange feeling to be the instrument by which a court in the end convicts a human being. That does not leave you cold, at least not if you have remained a human being yourself. But there was one thing I could say with a clear conscience after every single case, and it was the premise I never crossed in all those years: never, through my work, was an innocent person convicted. I never stepped over that shadow. Better no report than a false one.

What I gathered in that time was not only forensic craft. It was the knowledge of the people around me. I spoke with the forensic psychiatrists, with the psychologists, with the colleagues who had to look into the offender’s mind while I looked at his body and his traces. And I collected, as always, whatever was given to me. The human psyche is a singular thing, and nowhere does it show itself as nakedly as in crime. There every mask falls. There you see what the Homo sapiens is capable of, upward and downward.

Forget What Television Taught You About Profilers

Let us start with the disappointment, because that has to go first before the real thing has room.

The profiler you know from television does not exist. That figure who steps up to the crime scene, glances around once, the spattered blood, the position of the body, the choice of victim, and then announces in three publishable sentences that the offender is a white male between 30 and 35, lives alone, has a disturbed relationship with his mother and drives a dark station wagon, that figure is an invention of screenwriters. It makes for great television. As science it is about as serious as a horoscope, except that the horoscope puts no one in prison.

A study in 2008 put the uncomfortable truth fairly brutally. Snook and his colleagues titled their paper The Criminal Profiling Illusion, and they showed what the widespread belief in the accuracy of profilers actually rests on (Snook et al., 2008). Not on solid empiricism. But on anecdotes, on the constant repetition of the same success stories, on the label expert pinned to someone, and on a psychological trick we all know: we remember the hits and forget the misses. A profiler who makes ten statements, seven of them so vague they always fit, two of them wrong and one a spectacular hit, will be remembered as a clairvoyant. The one spectacular hit sticks. The rest vanishes.

In earlier work the same researchers reviewed 130 publications on profiling (Snook et al., 2007). The result is sobering. In 60 percent of the articles the most important source of knowledge was the anecdotal argument, the single story. In 45 percent it was testimonials, personal success reports. In 42 percent they simply appealed to an authority. And in only 42 percent did scientific evidence serve as a basis at all. Put differently: a field that claims to solve crimes is mostly written about the way one writes about a good wine, in stories and impressions.

Profilers tested under controlled conditions did not reliably outperform interested laypeople. Let that sentence sit for a moment. That does not mean every profiler is a charlatan. It means the myth of the infallible mind reader is exactly that, a myth.

Where does the method even come from? From Quantico, from the FBI’s Behavioral Science Unit, founded in 1972. Between 1976 and 1979 two agents, Robert Ressler and John Douglas, sat down in the prisons and held conversations with 36 incarcerated sexual serial killers (Ressler, Burgess & Douglas, 1988). They wanted to understand how these men thought, how they chose their victims, how they operated. Out of those conversations came the famous scheme of the organised and the disorganised offender, which haunts every crime series to this day and which is empirically far shakier than its popularity suggests. Ressler, incidentally, is credited with coining the term serial killer, which he formed around 1974, echoing the old movie serials, the cinema episodes that always ended on a cliffhanger and forced you to come back the following week. A murderer who does not stop, who keeps going, episode after episode.

There was also a more serious path, and it came from England. The psychologist David Canter built profiling from the ground up, out of data instead of intuition. His best-known case was the Railway Rapist, a man who raped along the train lines around London and ultimately also killed, together with an accomplice as later came to light. Canter’s analysis helped in 1986 to focus on a particular suspect, John Duffy, who in the end matched 13 of 17 features of the profile and was convicted (Canter & Heritage, 1990). That is a genuine success, no question. But Canter himself, and this is the decisive point, resisted the romantic figure of the profiler his whole life. He understood his work as a sober tool for steering investigations, as statistical pattern thinking, not as a gift.

And this is exactly where it gets interesting for me. Because if profiling is at its core pattern recognition, then my FBI man’s gut feeling may not have been a gut feeling at all. Perhaps it was something far more explainable. I will come back to that at the end.

A Crash Course in Real Profiling, Tool by Tool

Now I keep my promise and show you how it is really done. Not the television picture, but the craft. And with every tool I also show you the spot where it breaks, because a tool whose limits you do not know is more dangerous than no tool at all. We build this on an invented case, so that you do not just read it but can think along. Let us call the victim Mrs K., found in her flat, killed by numerous knife wounds. Any real resemblance would be coincidence, the case serves only as a teaching scaffold.

The analyst’s first move does not go to the offender. It goes to the crime scene, and it does so before anyone has a theory. That is exactly the order I know from my own work and have already described elsewhere in this text. First the trace, then the story. The analyst reads the crime scene like a text, and this text has a grammar. Where did the body lie, how was it positioned, what was taken, what was left behind, were there signs of struggle, of break-in, of familiarity between offender and victim. Each of these observations is a letter. Only together do they form a word.

Modus Operandi and Signature, the Most Important Distinction of All

Here comes the separation that my man from New York drilled into me that evening with the greatest patience, and that John Douglas, one of the founding fathers of the FBI approach, had to explain to juries for years, because it is so decisive and so often misunderstood (Douglas & Munn, 1992). Whoever does not understand it, he said, should keep his hands off crime scenes and rather talk about them on television. There are two completely different kinds of behaviour at a crime scene, and whoever confuses them pursues the wrong man.

The one is the modus operandi, the method. That is everything the offender has to do in order to commit the act successfully, to protect himself and to escape. How he got into the flat, what he controlled the victim with, how he tried to erase the traces. The decisive thing about the modus operandi is that it is learned and that it changes. An offender gets better. The first time he perhaps breaks a window, the third time he brings a lock pick because the window made too much noise. The modus operandi is dynamic, it is the handwriting of a learner. And exactly for this reason, this is Douglas’s warning, one must never link acts to one another by the modus operandi alone. For the same method can belong to two completely different offenders. Whoever climbs through the window is by no means the same as the next one who climbs through the window.

The other is the signature, and it is of an entirely different nature. The signature is what the offender does although he would not have to. A ritual that is superfluous for the act itself, but that fulfils a psychological need, serves a fantasy the offender carries around with him. In the FBI’s Crime Classification Manual there are two examples that show this with almost uncomfortable clarity. A bank robber from Michigan forced the employees to undress during the robbery so that he could photograph them. For the robbery that was entirely unnecessary, it even raised his risk. It was his signature. In another case a rapist forced the victim’s husband to come home and watch the humiliation. That too did not serve the act. It served the fantasy.

And here is the core you must remember if you leave this article with only a single insight: the modus operandi changes, the signature stays. The method is the craft that refines itself. The signature is the inner need that remains constant, because the fantasy behind it does not change. When an analyst wants to connect acts into a series, he does not search for the same method. He searches for the same signature. With our Mrs K. the number of knife wounds, far beyond what is needed to kill, would be a possible signature marker. No one needs 40 wounds to kill a person. Whoever stabs 40 times satisfies something other than the wish for the victim’s death. He satisfies rage, lust, control, something rooted deep in his biography.

There is a third element, and investigators readily overlook it, because it is made precisely to be overlooked. Staging, the staging. Some offenders deliberately alter the crime scene to lead investigators astray. They fake a robbery-murder where in truth a relationship drama took place. They open drawers and take a wallet so that it looks like a stranger, although the offender slept in the bed next door. An experienced analyst often recognises staging by the fact that the arrangement is too tidy, too much by the textbook, while real crime scenes are chaotic. If at Mrs K.’s the flat were ransacked but the expensive jewellery left lying open while only a cheap watch is missing, then something is wrong. Then the crime scene tells a story someone wanted to tell, not the one that really happened.

Victimology, the Person Who Was the Victim

The next step surprises most people, because it does not revolve around the offender but around the victim. Victimology it is called, the systematic study of the victim as the key to the offender. Who was this person? How did they live, where, with whom, in what rhythm? When were they vulnerable, and who knew that?

The reason is simple and cold at once. Most victims are not chosen at random. There is a relationship, however fleeting, between the life of the victim and the access of the offender. A victim who jogs alone at night is reached by a different type of offender than a victim who was vulnerable only in their own, locked flat. If Mrs K. died in her flat without a door being forced, then the circle narrows dramatically. Then she opened the door to the offender, and one does that only for someone one knows or whom one trusts for a plausible reason, the tradesman, the courier, the neighbour. The victim leads to the offender, because the victim is the last link of a chain at whose other end the offender stands.

Here too lies the fine line at which profiling becomes ethically delicate, and I name it openly, because looking away would again feed the lie. Victimology must never become a reversal of offender and victim, never the repugnant logic that the victim was to blame. It is not about blame. It is about access. The question is never what the victim did wrong, but solely who had the opportunity and the knowledge.

Geographic Profiling, the Map Betrays the Hunter

Now comes perhaps the most elegant tool of the whole field, and it is one of the few that is actually mathematically robust. When an offender commits several acts, he leaves a pattern on the map, and this pattern betrays where he lives. That sounds like witchcraft, but it is simple behavioural geography.

David Canter, the English psychologist I mentioned above, found something astonishing together with his colleague Larkin (Canter & Larkin, 1993). They examined serial rapists and established that in 87 percent of them the home lay within a circle whose diameter was determined by the two crime scenes farthest from each other. So one mentally stretches a circle over the crime scenes, and with high probability the offender sits right in the middle. These men Canter called marauders, because like predators they swarm out from their den into the closer surroundings. Opposite them stand the commuters, who deliberately strike far from home, in an area that has nothing to do with their normal life. In violent crime the marauder type is more common than in property crime, which makes the tool especially useful for murder and rape.

The Canadian Kim Rossmo turned this into a real science with formulas (Rossmo, 2000). His procedure, Criminal Geographic Targeting, rests on two effects that at first glance contradict each other. The first is the distance decay. The farther from his home, the more rarely an offender strikes, because every journey costs effort, time and risk. The second is the buffer zone. Directly in front of his own door an offender likewise strikes rarely, because there everyone knows him and no predator fouls its own nest, to put it politely. Out of these two effects arises a ring around the offender’s home in which the probability is highest, not too near, not too far, and Rossmo’s computer calculates from this pattern a probability map that tells investigators where to search first.

That is the one tool I trust without reservation, because it does not rest on intuition but on the plain fact that murderers too are people who do not like to walk far and do not want to stand out in front of their own door. But here too the limit sits right next to it. The whole procedure works only for the marauder, for the commuter it collapses, because his crime scenes precisely do not point to his home. And it needs several crime scenes. With a single act, with our Mrs K., the most beautiful map is no help.

The Inductive and the Deductive Method, Two Paths, One of Them Treacherous

Behind all of this stand two fundamentally different ways of thinking, and the difference between them is the reason why profiling is sometimes brilliant and sometimes catastrophic.

The inductive method works with statistics. It says, in the past offenders of this kind of act were mostly men of a certain age with a certain background, so this offender too is probably like that. That is useful, fast and rough. It is the same thinking with which an insurer calculates your policy without knowing you. It hits on average and fails in the individual case. The deductive method goes the opposite way. It infers, from the traces of this one, concrete crime scene alone, this one, concrete offender, without recourse to averages. It is more precise when it succeeds, but it demands a disciplined mind that reads only what is really there, and not what it wants to see.

And with that we are at the most dangerous spot of the whole craft. For both methods share a deadly weakness, and it is called confirmation bias. Once an analyst has a profile in his head, he begins to read the world through this profile. Every suspect who fits becomes more important. Every clue that does not fit is talked down. The profile stops being a tool and becomes the glasses through which one sees only what one already believes. Exactly for this reason I always read the file last in my own work. Whoever begins with the conclusion always finds the traces that support it.

When the Profile Hits the Wrong Man

How devastatingly this can end no invented case shows as well as a real one, and this one damaged profiling in Britain for years. In 1992 the young mother Rachel Nickell was murdered in broad daylight on a London common, with 49 knife wounds, before the eyes of her two-year-old son. There were hardly any traces, no usable DNA with the means of the time. Under the enormous pressure of the public the police brought in a renowned profiler, Paul Britton, who created an offender profile (Killing of Rachel Nickell, documented case; reporting 2008 to 2010).

Into this profile fitted, roughly, a man named Colin Stagg. His offence consisted essentially in the fact that he walked his dog on the same common and showed a few traits the profile named. What then happened is a lesson in confirmation bias in its purest form. The police set an undercover officer on Stagg, who over five months feigned a relationship with him and tried to elicit a confession by sharing violent fantasies with him. Stagg never confessed. He protested his innocence again and again. And here comes the diabolical core: his denial was not taken as a sign of his innocence, but reinterpreted as fitting the profile. The profile was so constructed that even the denial confirmed it. A theory that can no longer be refuted by anything is no longer science. It is a trap.

The trial collapsed in 1994, the judge sharply rebuked the honey-trap operation. By then Stagg had already spent a year in pre-trial custody and had been dragged through the press as a monster. Only years later, through DNA traces, was the true offender found, Robert Napper, a man who at that point had long been convicted of another, almost identical double murder, committed only 16 months after the act against Rachel Nickell. Had Napper been caught earlier, instead of fixating on Stagg, another woman together with her small daughter might still be alive. The bitterest twist: the profiler himself had expressly classified this other double murder as clearly different from the Nickell case. He was wrong not once but twice, and his misjudgement cost time that a murderer used.

That is the spot where the tool not only goes blunt but becomes a weapon against the wrong man. A profile is a hypothesis, not a verdict. The moment an investigator forgets that his profile could be wrong, a tool turns into an accelerant for the miscarriage of justice. Exactly for this reason the serious analysts I know work with so much caution and so little certainty. They know that the most dangerous profile is the one that can no longer refute itself.

The Brain That Kills

Now to the part that gets under the skin, in the literal sense. What is actually going on inside the head of a person who kills? Is there something to see there, something measurable, something that is different from you and me?

The answer is a cautious yes, and the caution is just as important as the yes.

The man whose name has to come up here is Adrian Raine. A British neurocriminologist who did something almost no one before him dared. He pushed murderers into the brain scanner. In 1997 he published, with his colleagues, a study examining 41 people charged with murder who had pleaded not guilty by reason of insanity, compared with 41 healthy controls of the same age and sex (Raine, Buchsbaum & LaCasse, 1997). Using positron emission tomography, a procedure that makes the sugar metabolism in the living brain visible, he watched them think.

What he found was a pattern. In the murderers the prefrontal cortex worked worse, that part of the brain right behind the forehead that functions as something like the brake of the personality. Impulse control, weighing consequences, suppressing a flash of rage, all of that sits up front there. In the murderers this region burned less energy, it ran, so to speak, in power-saving mode. To this came abnormalities in deeper structures, in the amygdala, the almond-shaped nucleus responsible for fear and for emotional appraisal, in the hippocampus, in the thalamus. The brake was weak, and the alarm system worked crooked.

In later work Raine found, in people with antisocial personality disorder, 11 percent less grey matter in the prefrontal cortex (Raine et al., 2000). 11 percent less of the material that makes us pause. And his colleague team later showed that the amygdala in psychopaths is deformed and reduced, precisely in the regions responsible for processing fear and empathy (Yang et al., 2009).

Now one could triumphantly say: there we have it, the murderer has a broken brain, case closed. That is exactly what I am not saying, and it is exactly what Raine himself emphatically warns against. These studies show a correlation, a statistical link. They show no cause. The murderers examined were a handpicked group, people who had pleaded insanity, so not the average offender. The task in the scanner was artificial. And above all: a brain is not a fate carved in stone. It is shaped, all life long, by what happens to it. A weak prefrontal brake can be congenital. But it can also be the result of blows to the head, of years of stress, of a childhood in which this region was never allowed to learn how to calm itself.

There are two cases that illuminate this ambiguity perfectly, and I love both, because they show how close biology and fate lie to each other.

The first is over 170 years old. In 1848 a young, reliable, well-liked foreman named Phineas Gage was working on a railway when a blast went wrong and shot an iron rod more than a metre long through his head, up from below through the cheek, through the front part of the brain, out again at the top. Gage survived. That is the one miracle. The other is what happened afterward. The friendly, dependable man was gone. In his place sat a moody, irascible, ungovernable person who made plans and abandoned them at once, who cursed where he had once been polite. His friends said he was no longer Gage. More than a century later researchers reconstructed, from his preserved skull, the exact path of the rod and confirmed what had been suspected: it had destroyed the ventromedial prefrontal cortex, exactly the region that links rational decision and emotion (Damasio et al., 1994). An iron rod had made one character into another.

The second case is newer and even eerier. In 2003 two physicians described a 40-year-old man who suddenly, with no prior history, developed a paedophilic interest and lost all impulse control (Burns & Swerdlow, 2003). They found a tumour in his head, in the right orbitofrontal cortex, again up front, in the region of inhibition. They removed the tumour. The symptoms vanished. Months later they returned, and the scan showed it: the tumour had grown back. They operated again. The symptoms vanished again. That is, as rare and as terrifying as it is, one of the cleanest causal proofs we have that a piece of tissue in the right place can make a person into someone he was not before and is not afterward.

What does that tell us? It tells us that the free will we so like to believe in stands on a biological foundation that can be brittle. But it does not tell us that every offender is a tumour patient. The vast majority of murderers have no hole in the head and no tumour. They have a brain that, through a long chain of dispositions and experiences, became what it is. And with that we come to the next myth, the most dangerous of all.

The Killer Gene That Is No Such Thing

There is a pretty, simple, false story, and it goes like this: some people are born with a gene that makes them killers. The Warrior Gene. Whoever has it is a ticking bomb.

This story is so seductive that it has made its way into courtrooms, where defence lawyers brought it as a mitigating circumstance, along the lines of, my client could not help it, his genes forced him. And in this form it is simply nonsense. But like every good myth it has a true core, and that true core is fascinating enough that you do not need to inflate it.

The story begins in 1993 in the Netherlands. A family in which, across generations, the men stood out through impulsive aggression, through outbursts of violence and arson, through sexual offences and through an inability to brake their own rage. The geneticist Han Brunner found in them a rare mutation that completely shut down a single gene, the gene for monoamine oxidase A, MAOA for short, an enzyme that in the brain breaks down, among other things, messengers like serotonin and dopamine (Brunner et al., 1993). Without this enzyme these messengers pile up, and the metabolism falls out of balance.

Here is the crucial thing that appears in no sensational version: it was a complete failure of the gene, a total knockout, and that is extremely rare. So rare that worldwide one speaks of a handful of families. That is no model for the population. That is a medical rarity. To build a warrior gene out of this rarity, one slumbering in every third man, is like inferring from a person with an extremely rare metabolic disease that everyone who likes sweets is terminally ill.

What does actually exist is a more harmless variant of the gene that is merely somewhat less active, and that one is common. It occurs in about a third of men of European descent. If this variant alone made killers, we would have a problem of biblical proportions. But it does not. And the proof of that is perhaps the most important study in this whole field.

In 2002 a team around Avshalom Caspi published a paper from a famous New Zealand long-term study in which people had been followed from birth over decades (Caspi et al., 2002). The researchers looked at who carried the low-activity MAOA variant, and who had been maltreated in childhood. And then came the result that changes everything. The gene alone did almost nothing. Maltreatment alone raised the risk of later violent behaviour, but only moderately. Whoever had both, the gene variant and the maltreatment, carried a massively raised risk of becoming violent. In the maltreated boys with the unfavourable variant the effect was highly significant. In those with the protective variant the maltreatment remained largely without consequence, at least on this level.

That is not a story about a killer gene. That is a story about a lock and a key. The gene is the lock. Childhood is the key. Without the key the lock stays shut. Only both together open the door to violence. This is called a gene-environment interaction, and it is the exact opposite of determinism. It does not say your genes determine your fate. It says your genes determine how vulnerable you are to what is done to you.

And so you do not think I paint it prettier than it is: later analyses pooling many studies found the effect sometimes confirmed, sometimes not (Byrd & Manuck, 2014). The exact strength remains disputed to this day. The science here is honest and unfinished, the way good science is. What stays stable, though, is the basic logic: disposition and experience are not opponents, they are dance partners. Whoever points only at the genes is as wrong as the one who points only at upbringing.

Why the Same Hell Makes Two Different People

If childhood is the key, we have to talk about childhood. And here there is one of the most impressive investigations of modern medicine, which did not begin with crime at all, but with an entirely different question.

In the 1990s Vincent Felitti and Robert Anda examined over 9,500 adult patients of a large American health insurer and asked them about distressing childhood experiences (Felitti et al., 1998). Maltreatment, abuse, neglect, a parent in prison, violence between the parents, addiction in the household. They added these experiences up and called the whole thing Adverse Childhood Experiences, ACE for short. Then they compared this number with health in later life.

The result hit medicine like a blow. The more such experiences a person had had in childhood, the higher his risk for almost everything bad that can happen to an adult. Whoever had experienced four or more of these categories carried a manyfold raised risk for addiction, for depression, for suicide attempts, and it continued into physical illnesses, heart disease, cancer, lung disease. And all of it dose-dependent, the more poison in childhood, the more damage across the entire rest of life. Childhood writes itself into the body, not as a metaphor, but as a measurable risk.

Toxic stress, early and lasting, shapes the developing brain. It sets the stress axis high, it shapes how a person later reacts to threat, whether he reads a harmless glance as an attack, whether his brake ever learned to grip. Here the circle closes back to Raine’s weak prefrontal cortices. Some of these weak brakes were not born that way. They became that way, because no one ever showed the child what being calmed feels like.

And now comes the question that troubles me most, because it pulls the ground out from under the whole determinism story. If childhood shapes so powerfully, why does not every maltreated child become a violent offender? Why do two brothers go through the same hell, and one becomes a murderer, the other a doctor?

The answer is called differential susceptibility, a clunky word for a beautiful idea (Belsky & Pluess, 2009). For a long time people thought some humans were simply more resilient, more robust, like a stone the storm bounces off. Belsky and Pluess turned that around. Some people, they say, are not more robust, they are more sensitive, and in both directions. They react more strongly to a bad environment, yes. But they react just as strongly to a good one. The same child that breaks in hell would have bloomed especially in the garden. They are sometimes called the orchids, in contrast to the dandelion children who get through almost anywhere, in the good and in the mediocre. The orchid needs the right soil. Without it, it withers. With it, it blooms more beautifully than anything else.

For me this is the most human finding of the whole research. It means that the same child who became an offender under blows might, under love, have become something extraordinary. The disposition toward depth is the same as the disposition toward destruction. It depends on what is poured in.

Why You Do Not Kill

Let us turn the question around now, the way a clever criminologist already did in 1969. Travis Hirschi, in his book Causes of Delinquency, did not ask the usual question, why some people become criminal (Hirschi, 1969). He asked the opposite, and that was the brilliant move: why do most people not become criminal? Why do you keep to the rules, when you could break them every day?

His answer was the social bond. Four threads, he said, hold us in the net of society. The attachment to people who matter to us and whom we do not want to disappoint. The commitment to what we have built and would lose. The involvement in a daily life that occupies us. And the belief in the validity of the rules themselves. Whoever has these threads is held. Whoever loses them does not inevitably fall, but he can fall, for nothing holds him anymore.

I can pin this down very precisely in myself, and I say it without any vanity, rather the opposite. I would never commit a crime. Not because I am a better person than others, but because two very concrete things hold me back. The one is fear. The sober, almost banal fear of prison, of social ruin, of losing everything I have built. The other is my upbringing. I come from a strict house, with clear values, with rules that have soaked in so deeply that today they are no longer external rules, but a part of me. An inner brake that long ago stopped needing a command. Exactly what Hirschi called belief, and what faltered in Raine’s offenders in the scanner.

This inner brake has a biological name, and it is empathy. If I were to inflict pain on another person, something in me would hurt as well. That is no parenting platitude, it is measurable. When we perceive the pain of another, a network activates in our own brain, the anterior cingulate cortex, the insula, the amygdala, the orbitofrontal cortex, and it produces an unpleasant, aversive reaction in us (Decety, 2011). This reaction is the natural inhibition. It is the reason most people cannot stab, even when they are angry enough. In some violent offenders, especially those with psychopathic traits, exactly this resonance is dampened. The pain of the other does not reach them. The brake is missing because the signal is missing that would have to trigger it.

And now you see how everything fits together. The weak prefrontal brake in Raine. The dampened amygdala. The missing social bond in Hirschi. The unfavourable gene variant in Caspi. The burdened childhood in Felitti. Not one of these factors by itself makes a murderer. But they add up, they reinforce one another, they mesh into one another, and at some point the door that stays locked for you and me stands, for another person, a crack open. It then takes only the situation that pushes it open.

Skin Colour, Testosterone, and a Fallacy That Makes a Career

Now I have to reach a point many people dodge, and I do not dodge it, because looking away feeds the lie. Look at the American prisons and you see an oppressive imbalance. Black Americans are behind bars at roughly five times the rate of whites (Nellis, 2021). One in 81 black adults is in a state prison. In some states more than half the prisoners are black, although black people make up only around 13 percent of the population. That is a fact. The question is not whether this imbalance exists. The question is where it comes from.

And here there is a comfortable, biologistic answer that keeps crawling out of the swamp: maybe it is the testosterone. Black men, so the claim goes, have higher testosterone levels, and testosterone makes you aggressive, so they are more criminal. This chain sounds logical to some. It is nonetheless wrong at every single link.

First, even the link between testosterone and violence in humans is far weaker than the bar-stool believes. The clean causal evidence for it is thin (Eisenegger, Haushofer & Fehr, 2011). Testosterone does not make a brawler, it sharpens the striving for status, and whether that translates into violence or into an ambitious business deal depends on the context. Second, and this is the actual neck-break of the thesis, it was shown more than 30 years ago, in over 4,000 men, that social status bends the whole link (Dabbs & Morris, 1990). In men from higher circumstances the connection between testosterone and antisocial behaviour was far weaker than in men from poor circumstances. In other words: what looks like biology is in truth poverty. The hormone is not the perpetrator. The circumstances are.

For the true explanation of the American prison statistic is structural, and it is as uncomfortable for the other side as the testosterone thesis is for this one. Michelle Alexander laid it out in her book The New Jim Crow (Alexander, 2010). A War on Drugs waged deliberately in poor, black neighbourhoods, while in the white suburbs the same drugs were consumed and barely pursued. Minimum sentences that struck hardest at exactly those substances common in poor districts. A selective policing that looks where it wants to look. A bail system that keeps the poor in jail and sends the rich home. That is no biological phenomenon. That is a built system that produces what it claims to fight.

And this is exactly where the greatest proof against any biologistic explanation of violence at all lies, and it lies in a single number I will come to in a moment. For if genes or hormones or skin colour explained killing, then the murder rate between two countries with the same human biology would have to be roughly equal. But it is not. It differs by a factor of five to six. And the difference has nothing to do with biology and everything to do with the circumstances people create for one another.

668 Against 16,000

Let us look at the bare numbers, and let us look closely, for here a lot of cheating goes on, even by people who should know better.

In Germany the police crime statistics for 2024 report, under murder, manslaughter and killing on request, 2,303 cases (Bundeskriminalamt, 2025). This number is gladly carried through the headlines, and it is misleading, for it consists predominantly of attempts. Actually completed were 584 of these acts. Counted by victims who really died, the federal office arrives at 668 people in the year 2024. 668. In a country of over 83 million inhabitants. That yields a murder rate of not even one homicide per 100,000 people, roughly 0.9. The clearance rate for these acts lies above 94 percent. Almost everyone who kills here is found.

In the United States the FBI reported for the same year 2024 a murder rate of 5.0 per 100,000 (Federal Bureau of Investigation, 2025). With a population of around 340 million that comes to more than 16,000 killed people in a single year. And here is the twist no one expects: that was a good year. The rate fell against the previous year by nearly 15 percent, the largest single-year drop ever measured, after it reached its two-decade peak in 2020 at 6.7. Even after this historic drop, in the United States, measured against the population, five to six times as many people die by murder as in Germany. Three of four of these killings happen with a firearm.

668 here. Over 16,000 there. The same species. The same brain, the same genes, the same amygdala, the same testosterone. The difference does not lie in the human being. It lies in the world the human being has built around himself. In the availability of weapons, in social inequality, in the question of whether a quarrel ends with fists or with a shot. Whoever wants to understand the murder rate need not look into the genes. He has to look into society.

In the extreme acts of violence, in rape, in the rare, media-heavy serial killers, the ratio is similarly skewed. In the area of rape and sexual coercion alone, Germany counted over 13,000 cases in 2024, with a clear rise that also has to do with changed reporting behaviour. But the truly large, serial cases, the cases where a profiler genuinely becomes the means of choice, are rare in Germany. In the United States they are common enough that a whole discipline has formed around them.

Do We Actually Know a Single German Profiler?

And that brings me to an almost comic observation. In the United States the profiler is a cultural figure. In Germany most people do not know a single real profiler. They know a man who appears regularly in a certain large tabloid and is occasionally interviewed on public broadcasting when a spectacular case happens somewhere. I name no name, for I do not want to discredit anyone here, and it is not necessary either. But I confess that I have to smile every time this gentleman delivers his remote diagnoses, with the certainty of a shaman reading the coffee grounds, while the viewer nods, because he mistakes certainty for competence. That is exactly the difference. For I know the real ones. I know one of them quite well, and I have just spent hours with a second. And the real ones talk completely differently. More cautiously. More soberly. With less certainty and more knowledge.

This also has an institutional reason. Germany has no profilers in the American sense, because it has something else, the Operative Case Analysis, OFA for short, located at the federal and state criminal police offices (Bundeskriminalamt; Dern, 2000). These units work pointedly factually, in teams, data-supported. The federal office itself puts it dryly and beautifully: police case analysts are no clairvoyants, no readers of coffee grounds or crystal balls. An offender profile is there only one tool among several, and it may only be drawn up after a thorough analysis of the course of the crime has gone first. A profile without this preparatory work, the federal office says, would be unserious. The whole media term of the profiler, it states in essence, misses the reality of these offices.

I do not mean by this to place the German authorities above the American ones, on the contrary. My honest assessment after everything I have seen and heard is that the American investigative authorities are far ahead of us in many things, in experience, in the sheer volume of cases on which one learns, in the meshing of science and practice. That is no disparagement of the German work, which is excellent and often cleaner through its sobriety. It is simply the consequence of the numbers. Whoever has to solve 16,000 killings a year gathers a different depth of experience than the one who has 668. Hell is a hard but thorough teacher.

What the Gut Feeling Really Was

With this I am back at the end with the man from New York with whom it all began, and with his gut feeling that occupied me so.

I believe I now know what it was, and it was no magic. It was the exact opposite of what goes wrong in the brain of an offender. Let us remember: in the offender pattern recognition is often disturbed, the brake weak, learning from consequences impaired. In the experienced profiler exactly this machinery is polished to a shine. Over decades his brain has seen thousands of cases, thousands of crime scenes, thousands of faces, thousands of patterns. At some point this experience works faster than conscious thought can follow. It delivers a result before the reasoning is formulated. That feels like a gut feeling. In truth it is compressed experience, pattern recognition in its purest form, the same ability to infer from the past onto the future that the offender lost or never had.

The same tool, then, the same brain region, the same function. In one broken, in the other perfected. The difference is the direction in which it points. And perhaps that is the most uncomfortable insight of this whole text. The profiler and the murderer are neurologically more alike than either would like. Both read people. The one to hunt. The other to catch the hunter.

I spent my entire working life looking into faces and asking myself how a person is capable of such a thing. The answer I can give after all those years and after this conversation and after these weeks of reading is not reassuring, but it is honest. There is no monster. There is only a person in whom too many things fell in the wrong direction. An unfavourable disposition, a destroyed childhood, a weak brake, a missing bond, a dampened empathy, and at the end a situation that brought it all to explosion. Every single one of these things almost every one of us carries within, to some degree. In most it never suffices. In a few it suffices.

This is exactly why the killer is no monster. He is the living proof that none has to exist. That it takes no alien, evil being to do the unthinkable. That a person suffices, to whom too much has happened.

Would you have thought profiling works like this? That behind the gut feeling lies no gift, but statistics? That behind the monster lies no monster, but biology and biography? I, for one, learned more about killing from this man from New York than from many a file. And the most important thing I learned is that the most frightening thing about the murderer is not his strangeness, but his nearness.

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