At the heart of nearly every irresistible psychological thriller is a simple, deliciously dangerous idea: someone the protagonist knows—or has recently met—isn’t at all who they appear to be.
In these novels, trouble never bursts through the door wearing a ski mask. It strolls in smiling—capable, reassuring, perhaps downright charming. Sometimes it’s even the person brushing their teeth next to the protagonist in the morning. Then, either in one jolting moment or through a slow drip of unease, she realizes she’s missed something crucial. The danger didn’t arrive late. It was there all along.
What makes this premise so compelling is that it’s hardly confined to fiction. Real life is full of people who aren’t as advertised—and unlike in novels, uncovering that truth never ends up being delicious. The fallout doesn’t necessarily involve a body (at least let’s hope not), but it can still leave plenty of wreckage behind.
After researching and writing nineteen mysteries and thrillers (my latest is I Came Back for You, March 1, Thomas & Mercer), I’ve spent a lot of time talking to experts about deception. What I’ve learned has not only helped me sharpen my plots, but it’s also sometimes proved useful in my personal life.
Here are my favorite strategies for spotting a deceiver, even if he is brushing his teeth next to you in the morning (unfortunately, I speak from experience in that case!)
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Don’t Bother Becoming a Body-Language Expert
When body language first became a popular topic, books and articles promised that liars routinely gave themselves away through specific expressions and gestures. A hand over the mouth. Eyes looking up to the right. Learn these so-called “tells,” the thinking went, and you could protect yourself from deception.
The problem is that this approach isn’t foolproof. “Tells aren’t universal,” explains psychologist Dale Atkins, author of eight books, most of which focus on self-development. “They vary from one person to the next.” Some people fidget, touch their face, or avoid eye contact simply out of habit or anxiety. And many commonly cited tells, she notes, are influenced by gender and culture, which makes them far less reliable than we tend to believe.
I touch on this I Came Back for You. The protagonist, Bree, must decide whether a young woman who comes forward with a confession is telling the truth—because the information could be crucial to the reinvestigation of her daughter’s murder. Bree notices that the woman looks away several times while speaking, which initially strikes her as evasive. But her ex-husband points out that it could just as easily be a sign of nervousness.
And he’s right. It might be.
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But Do Notice the Biggest Tell of All
While many so-called tells vary from person to person, there’s one type of behavior that consistently shows up with deception: inconsistency. “If someone offers an explanation and the details shift in the retelling—or if they later give you a suddenly expanded version—that should be a red flag for you,” says New York City psychiatrist Dr. Karen Rosenbaum.
Why can’t pretenders keep their facts straight? “When people lie, they’re also hearing themselves and deciding how the story sounds,” says Will Valenza, the retired chief of the Glens Falls NY police department. “They start worrying that you’re not buying it, so they gradually add details or even change certain details to make the story seem more credible. You see this a lot in news coverage of men who’ve murdered their wives and initially offer an explanation for why the women might be missing.”
Also pay attention to inconsistencies in a person’s actions. For example, do they behave one way with you and another with the waiter? Do they promise to take care of something and then don’t? This type of mismatch can be far more revealing than any fleeting gesture or facial expression.
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Be Wary of Perfect Memories
A deceptive person will often rehearse a fake story in their mind, embellishing it with plenty of details in order to make it seem very real or to detract from the core lie they’re trying to bury. If you listen closely while they’re relating the story, you can notice that it sounds almost too precise.
I.S. Berry, author of the award-winning espionage novel The Peacock and the Sparrow, spent six years as a CIA counterterrorism officer, partly in wartime Baghdad. Part of her daily job was evaluating people who claimed to have valuable intelligence.
“When I spoke to someone, I always had to ask myself: could this information be trusted?” she says. “One of the things I came to see over time is that no one should know every detail. Let’s say the intel involved cars—there were so many car bombings. If someone rattled off multiple license plate numbers to me, I knew to be suspicious.”
In short: if what you’re hearing feels impossibly precise or overly elaborate, treat it as a warning.
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Try a Very Pregnant Pause and See If It Leads to Squirming
BBC presenter and acclaimed media consultant Laura Trant has a deceptively simple trick for spotting liars during interviews she’s conducting as a journalist: just go quiet and wait.
“Silence can be very destabilizing for someone who’s lying,” she explains. “It makes them wonder if you’re buying what they’re saying—and then they start working harder to convince you.”
The result? She says they might start to perspire a little, shift in their seat, speed up their speech, or contradict themselves, which brings us back to lack of consistency. Trant calls these “micro-contradictions,” and says they’re often the clearest clue that you shouldn’t fully trust what you’re hearing.
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Dare to Be a Data Detective
Okay, let’s say you’ve been listening and something really feels off to you. Challenging what you’ve heard head-on isn’t likely to pay off so it’s time to do some digging. It might seem extreme, but that’s exactly what happens in professional evaluations. Forensic psychiatrists, for example, assess a person’s mental state, competence, or criminal responsibility not just by talking to them, but by checking records and speaking with people in their orbit.
“Yes, the one-on-one evaluation is important,” says Dr. Rosenbaum, a highly regarded forensic psychiatrist. “But we’re not human lie detectors. We also gather outside information to see if things match up or not.”
Even ER doctors rely on this approach. Dr. Paul Paganelli, the retired head of a busy ER in Massachusetts, recalls countless times paramedics or family members revealed critical details that helped him understand that what a patient had shared was incorrect. “An elderly patient with a hip fracture might have told us they simply tripped,” he says, “but when we turned to the EMS for input, they’d reveal that the person fainted and fell after chest pain. A whole different story, requiring a different course of treatment.”
Now, I’m not suggesting you hack someone’s computer or scroll through their texts (ha, that’s between you and your conscience). But if your instincts are on high alert, there’s nothing wrong with confirming details through public records, online research, or trusted contacts. As Dr. Rosenbaum puts it: “If someone is being truthful, they have nothing to fear from you doing a little factchecking.”
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Most of All, Don’t Resist the Uh-uh Moment!
No matter how skilled you get at spotting deception, it won’t help if you ignore your instincts. “You have to pay attention to that gut feeling that says ‘uh-oh,’ something’s off and is making you feel confused or uneasy,” says Dr. Atkins.
Our minds, she explains, love to rationalize inconsistencies and make excuses—but one of the biggest mistakes you can make is dismissing that inner alarm. “Stay with the feeling,” Atkins advises. “You want to grab hold of it before your brain talks you out of it.”
And if you recognize that there’s a serious problem? Be bold enough to put distance between you and the pretender. “Just remember that if they’ve been lying,” says Dr Atkins, “you’re under no obligation to offer them an explanation, which will only give them a chance to try to talk you out of your decision.”
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