What Crime Writers Get Wrong About Behavioural Analysis

Fri, 7th August 2026

Part of my Crime Fiction Experts series

Lesley McEvoy on behavioural analysis and building characters

You know the scene. The profiler arrives at the cordon, ducks under the tape, takes one long look at the room and delivers the verdict.

Here’s Lesley McEvoy’s version of it: “The offender is a white male; 5’7″ in height. Left-handed with a limp and lives at 27 Letsby Avenue.”

It’s an old joke in British policing, and Lesley uses it to make a serious point about where our idea of profiling actually comes from.

“Hollywood has a lot to answer for,” she says. Popular culture attached the word profiler to FBI behavioural work, and the department name and the job title fused together in the public imagination.

Lesley is a behavioural analyst and psychotherapist who has worked with prisons, the security services, the transport industry and the corporate world. She’s also five books into her Yorkshire crime series featuring Dr. Jo McCready. That puts her on both sides of the desk.

What interested me most was what she does with all that experience once she sits down to write. Before Lesley puts a character on the page, she profiles them too. We’ll come back to that.

The job doesn’t have that name here

If your book is set in Britain, this is the correction that matters most.

“In the UK, police and forensic psychologists don’t tend to use the term ‘Profiling’, but rather Behavioural Analysis, which emphasises a more scientific, data-driven approach to major crime investigations.”

It’s now a recognised profession, managed by the National Crime Agency, and the people doing it are called Behavioural Investigative Advisers rather than profilers. Lesley puts the writing rule plainly:

“If your fiction is set in the UK, then strictly speaking, your ‘profiler’ should either be employed by the NCA as a BIA or a police officer with specialised training.”

That doesn’t shut outsiders out altogether, and Lesley is clear that other disciplines do get drawn into investigations. What she objects to is a much more specific character:

“Any fiction that has a lone profiler, even worse, one who isn’t attached to the official investigation in any way, walking into a crime scene, taking one look and then saying something like…”

And then we’re back at 27 Letsby Avenue.

In her own books, Lesley gives Jo McCready a forensic psychology background and brings her in on investigations where the psychological elements are unusual. Jo uses the word profiler as shorthand because most readers recognise it, and the books keep the distinction visible rather than letting it blur.

What a profile is actually for

Modern offender profiling grew out of two schools. The top-down method came from the FBI’s Behavioural Science Unit in the seventies and eighties, and builds a narrative from the practitioner’s own experience of previous cases. The bottom-up approach of investigative psychology was developed here in the UK by Professor David Canter, and builds a picture from case data and statistical patterns.

In practice, Lesley says, the two approaches complement one another: “Top-down for rapid working theories and interview strategy, bottom-up to test those theories.” Top-down can give investigators direction early, helping them prioritise the door-to-door canvassing and the media appeals. Bottom-up needs good data and time, so it’s less use in the frantic opening days.

Lesley’s summary of what a profile is for is worth copying out somewhere:

“Profiles are used to generate tasks for an investigating team. They never provide the name and address of an offender and wouldn’t be treated as concrete proof of identity. Just one tool in the toolbox of complicated and sophisticated modern enquiries.”

A profile is a way of deciding where to spend your people. If your profiler hands the SIO a suspect, you’ve skipped the entire investigation your readers came for.

Narcissists and psychopaths are not the same

This is where Lesley says writers go wrong most often. Her starting point is that neither word should be used as shorthand for madness.

“Narcissism and psychopathy are not mental illnesses. They are personality disorders and are not considered as insanity in a legal sense.”

So psychopathy on its own doesn’t explain a character who hears voices, or has delusions, or loses contact with reality. If that’s happening on your page, you’ve introduced something else as well, and Lesley is blunt about how the muddle usually reads:

“If your villain is a psychopath, he’s not going to hear voices (unless he’s also suffering from a mental illness such as schizophrenia). He’s not going to go around foaming at the mouth and muttering to himself. If he did, he’d be really easy to catch!”

They do overlap heavily. Both manipulate other people and lack empathy, and both carry an air of entitlement that lets them treat everyone around them as a means to an end. Where they separate is in what the ego feeds on.

The narcissist’s ego is fragile. “Narcissism is built around insecurity and fragility of ego. They are thin-skinned and reactive and very sensitive to any perceived criticism of themselves or their abilities.” They need what Lesley calls a constant stream of attention, praise or validation to keep themselves propped up, and they collect people who supply it. “Anyone who doesn’t is cut off and cut out, often with scathing character assassination to justify why they are no longer in the inner circle.”

Which means a narcissist can feel shame. They’re “sometimes genuinely remorseful if they get caught out doing a bad thing”, Lesley says, though that’s because the bad thing makes them look bad to others, and they’re hyper-sensitive to what other people think.

The psychopath needs nobody. “Psychopaths have a very strong sense of themselves. Their ego is fed from within and doesn’t need the praise of others to feed it.” They are, as Lesley puts it, “cold, calculating, and motivated by power and dominance over other people”, and “it’s almost impossible to hurt their feelings, because they’re just not that sensitive.” They can perform warmth convincingly, but “it’s a shallow effect with no roots in reality”, and the performance can be switched off in a second, usually to the horror of anyone who thought they knew them.

Put the two of them in the same humiliating scene and you’ll get different reactions for different reasons. The narcissist feels the wound to their image, because their sense of themselves depends on what the room thinks. The psychopath doesn’t need that approval at all, though Lesley notes they can still feel anger and rage when their authority or their opinion is challenged.

Psychopath doesn’t mean killer

One of Lesley’s best-known observations is that she found more psychopaths in business than in prison, and it’s worth understanding why that isn’t the joke it sounds like.

“Their brains are simply not wired the same as the rest of us.” In early childhood, she says, they probably assume everyone experiences the world as they do. It’s only as they begin mixing with other children that they realise they’re somehow out of step, and “in order to blend in and not stand out as ‘different’ they learn to ‘mimic’ the emotional responses they observe in others.”

I hadn’t thought of it as something learned before.

Most of them never hurt anybody. “The truth is that the majority of psychopaths are non-offending. They have families, hold down jobs and lead perfectly ‘normal’ lives. They could be sitting next to you in a restaurant or living next door.”

And the traits are frequently an asset. Charm and confidence go a long way in an organisation, and as Lesley puts it, “They can make hard decisions and sleep at night.” A lack of concern for the people on the receiving end makes those decisions easier to take. Businesses notice people like that, promote them and pay them well for it.

Which is a useful corrective to the sheer number of psychopaths currently roaming through crime fiction.

“So many people tell me that their ex-partner was a psychopath or narcissist, that if it was true that would be the majority of the population.”

The figure Lesley gives for the UK is around 0.6%. Her point isn’t that cruel or controlling behaviour is harmless, only that it doesn’t automatically earn a clinical label.

Does your crime scene match your killer?

Something I saw again and again in my 30+ years of policing, and which crime fiction still resists: most murders aren’t planned by anybody clever. Lesley’s experience in prisons across the UK matches it. “The majority of murders are committed by ordinary people in a ‘moment of madness’.” Drink or drugs, an argument that runs away with everyone in it, and people end up somewhere they never intended to be.

Fiction wants more than a pub brawl, which is why we all reach for the cold and calculating killer. Fine. Just make sure the scene you’ve written and the killer you’ve described are the same person.

That’s the practical value of the old organised and disorganised split that Hazelwood and Douglas proposed back in 1980. Lesley is upfront that it’s an oversimplification which has been refined since, but as she says, it stops you creating “a crime scene that is at odds with the killer you then go on to describe”.

In the original model, the organised offender leads an orderly life and is probably in a relationship. Everything about the scene reflects planning and control. They brought what they needed with them, restraints and weapon included, and they had the social skills to talk their way in rather than force it. They kept hold of themselves and of the victim, left very little behind, and they’ll often follow the coverage afterwards.

The disorganised scene, in contrast, suggests a crime committed in the heat of the moment with whatever was to hand. There’s little or no evidence of planning, and self-control has gone. Blood, prints and quite possibly the weapon get left behind.

Real scenes are messier and often carry features of both. Lesley’s advice there is to work out which is dominant. Does the scene show more planning, or less? That gives you your baseline.

There’s also a detail worth building a series around. “Their first offence is the one where more mistakes will be made.” If they aren’t caught, they learn from it, becoming more forensically aware as they refine their method. So the earliest crime is the one that tells you most about who they really are, which gives a crime writer a useful structural possibility, particularly in a cold case.

The profile that never reaches the page

Now for the part writers can take directly into their own work. Before a character appears in one of her books, Lesley profiles them.

“I sit and write a ‘profile’ of that character. Their childhood; relationships with parents and siblings; life experiences etc. Most of that may never end up in the book, but it means that when I introduce that character on the page, I have a fully formed vision of how they behave and think.”

Most of that work stays invisible. What it buys you is that when you drop the character into a situation you hadn’t planned for, you already know how they’d behave.

It applies hardest to villains. Lesley has met and spoken to people who’ve committed awful crimes, and “what strikes you is that they don’t always see themselves as the villain”. In prison, very often, they see themselves as the victim: of circumstance, of a traumatic childhood, of the justice system. They’re complicated people with mixed and competing drives, same as everyone else.

“Criminals don’t pop up out of a void. They’ve come from somewhere.”

You don’t have to like the answer you arrive at, and you certainly don’t have to excuse it. But you need to know what brought them here, even if the reader never sees a word of it.

Don’t forget who it happened to

Lesley ran a private therapy practice for years, listening to people describe “the raw emotional pain they were feeling and how events had affected their lives and the lives of those around them, and that never leaves you.”

She’s also old enough to remember when the system barely acknowledged any of it. In the seventies and eighties, she says, “victims were treated as witnesses and had virtually no formal support”, generally forgotten once the case had been through court.

I joined in 1983, and I remember that too. Victims were treated first as a source of evidence, with far less thought given to what happened to them afterwards. It’s one of the genuine improvements I saw over my 30 years, and it’s recent enough to be worth remembering if you’re writing about an earlier period.

So when she introduces a victim, she humanises them. “They’re not just a white outline at a crime scene, or an anonymous corpse.” She shows what their absence does to the people who loved them, and if they survived, what it’s still doing to them years later.

“In a crime, there are rarely any bit parts. They’re all equally important for the story to work.”

And one howler to avoid

Being a novelist herself has made Lesley especially forgiving of other writers’ mistakes. Slips that survive several editors and a big publishing house, she says, are easily forgiven. What she finds harder is the error that five minutes of research would have prevented.

Her example: a novel set in the UK in which every police officer wore a gun in a side-holster.

“Readers today are very sophisticated and will jump on glaring mistakes, and rightly so.”

She’s right, and they’re getting more sophisticated every year.

All of which is a long way from 27 Letsby Avenue. The profile that matters most in your book is the one that never appears in it, the one you wrote before chapter one and kept to yourself.


Lesley McEvoy is a behavioural analyst, profiler and psychotherapist whose career has included work with prisons, the security services, transport organisations and corporate clients. She’s the author of the Dr. Jo McCready series, set in Yorkshire and now five books in, and she’s one of my Crime Fiction Experts. If you want your psychology to stand up to a reader who knows the difference, she’s the person to ask. You’ll find her on my website here.

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