About The Author

Markus Lehmann never set out to become an expert on deception. Born and raised in Munich, he had always been fascinated by human behavior. As a child, he would observe people closely—how they spoke, how they moved, how their expressions sometimes contradicted their words. But it wasn’t until his late twenties that he realized just how much deception influenced everyday life.

In 2006, at the age of 28, Markus worked as a corporate consultant for a major German firm. His job required him to negotiate deals, analyze clients, and assess risks. It didn’t take long for him to notice a pattern: the most successful people weren’t necessarily the smartest or hardest-working. Instead, they were the ones who could read between the lines—the ones who knew when someone was lying.

One experience changed everything.

During a high-stakes meeting, Markus was responsible for finalizing a multi-million euro partnership. The opposing party, a charismatic businessman, reassured him repeatedly: “Trust me, Markus. This deal will benefit everyone.” On the surface, everything seemed perfect—until Markus spotted a small inconsistency in the financial reports. Something wasn’t adding up. He hesitated, but his instincts told him to dig deeper.

A week later, it all unraveled. The company they were about to partner with was hiding massive debts. If Markus hadn’t caught the deception in time, his firm would have suffered catastrophic losses. That was the moment he became obsessed with understanding how and why people lie.

Over the next decade, Markus devoted himself to the study of psychology, body language, and behavioral science. He trained with forensic interviewers, studied classic works on deception, and even spent time analyzing interrogation techniques used by intelligence agencies. The more he learned, the more he realized how deeply deception was woven into everyday life—not just in business, but in friendships, relationships, and society as a whole.

By the time he turned 40, Markus had built a reputation as a deception expert. He began consulting for law enforcement agencies, teaching professionals how to detect lies in high-pressure situations. But there was one thing missing—his knowledge was limited to a small group of specialists. He wanted to help ordinary people navigate the world of deception, to teach them how to protect themselves from manipulation and use their understanding of lies to their advantage.

And so, Why Do You Lie? was born.

Now, at 46, Markus Lehmann is one of the most sought-after speakers on human deception. His book has helped thousands of readers see through lies, negotiate better deals, and build stronger, more honest relationships. He still lives in Munich, where he enjoys a quiet life with his wife and two children—when he’s not traveling the world, teaching people the truth about lying.