How to interrogate a suspect: 7 techniques that work

Case file 08 · 5 minute read

Good interviewers do not shout. They get the story first, then let the story do the damage.

To interrogate a suspect well, get them to commit to a detailed account, then test it with evidence they do not know you have. That order comes from police interviewing research, and it is how you win in Break the Suspect, a voice game where you question AI suspects who lie.

The seven techniques

1. Start wide. "Walk me through your evening" gets more than "Were you there?" A yes or no gives you nothing to check. The UK's PEACE interview model is built around this free account.
2. Pin down the details. Times, rooms, who else was there. Every detail is a promise they have to keep later.
3. Hold your evidence back. Researchers call this the Strategic Use of Evidence. Ask questions around what you know before you reveal it. A liar who does not know what you have will often walk straight into it.
4. Show one piece at a time. Put it on the table, then ask them to explain it. Do not explain it for them.
5. Use silence. After an answer, wait. People fill a quiet room, and the extra sentence is often the one they had not rehearsed.
6. Ask for the story backwards. Studies by Aldert Vrij and colleagues found that telling events in reverse order is harder for liars, because an invented story is rehearsed in only one direction.
7. Go easy before you go hard. Rapport gets people talking. Pressure too early gets you short answers, or a lawyer.

Five questions to open with

• What did you do that evening, from start to finish?
• Who saw you, and when?
• When did you last see the victim, and how did they seem?
• Who would want to hurt them, and why?
• What did you do right after you heard the news?

Mistakes that end the interview early

• Accusing in the first minute. They close up, and you have learned nothing.
• Showing everything at once. Once your evidence is out, they can build a story around it.
• Asking two things in one question. They answer the easy one.
• Forgetting the other suspects. Two accounts that disagree are worth more than one that sounds nervous.

Try it on a suspect who lies back

In Break the Suspect you sit across from AI suspects with a fixed truth to protect. You ask anything by voice or by typing, slide evidence across the table, and only a full confession closes the case. Push too hard and they ask for a lawyer. It runs in Safari or Chrome with no install, and the game is played in English.

Quick answers

Is this how real police interrogate?

These techniques come from published interviewing research and training models such as PEACE. Practice varies by country. Here they are for a game.

What is the best first question?

An open one that asks for the whole account, such as "Tell me about your evening."

Can I practise this for free?

Yes. The briefing and the first five to seven questions of every case are free.