Detective Questions to Ask
Twenty questions for investigative interviews, whether you work a case, report a story, or run internal enquiries. They are sequenced the way a good interview runs: routine first, then the free account, then timing, place, people, and only afterward the tests of reliability. Order matters here as much as wording.
The questions
Open any question for the note
What were you doing in the hour before you noticed anything?
Why ask it
Starting in ordinary routine gets someone talking without pressure and sets a baseline for how they describe unremarkable events. Gaps and rehearsed passages later stand out against it.
Can you walk me through exactly what happened, step by step?
Why ask it
Ask this once, early, and then stay quiet. Interrupting an uninterrupted account is the most common way interviewers lose detail they never get back, because the person starts answering you instead of remembering.
What happened immediately before and after that?
Why ask it
People narrate the incident and drop the frame around it. The minutes either side often carry the detail that can be checked against someone else's account.
What time was this, and how do you know the time?
Why ask it
The second half is the question. A time anchored to a phone, a train or a television program can be verified; a time offered as roughly nine is an estimate that will drift by the next interview.
Where exactly were you standing, and what could you see from there?
Why ask it
Sightlines fix the limits of a witness account. Someone who describes something their stated position could not have shown them is not necessarily lying, but the detail came from somewhere else.
Who else was there, and what was each of them doing?
Why ask it
Asking what people were doing rather than who was present produces names that a general question misses, including people the witness does not think of as involved.
How do you know the people who were involved?
Why ask it
Relationships explain both motive and slant. Watch particularly for a connection that is described more distantly than it is, since that understatement is usually deliberate.
What did you see, hear or smell that was out of place?
Why ask it
Naming senses other than sight tends to unlock details that visual recall leaves out, and anomalies are what a general request for an account reliably drops.
Can you take me through it again, starting at the end and working backward?
Why ask it
Reversing the order tests recall rather than memory of a story, since a rehearsed account is hard to run in reverse. Do this only after you have the full account in the normal direction.
Which part of what you have told me are you least sure about?
Why ask it
Inviting doubt is safer than challenging a detail, and people usually take the invitation. The part they nominate is the part to check first rather than the part to disbelieve.
Which details did you fill in from what other people told you afterward?
Why ask it
Witnesses absorb each other's accounts within hours and rarely notice the seam. Asking directly separates what was observed from what was later assembled, which cross-examination will do anyway.
Who have you talked to about this, and what did you tell them?
Why ask it
Earlier retellings give you both consistency checks and further witnesses. A person who has discussed it with nobody at all is unusual and worth a gentle second pass.
Is there a message, receipt or recording that would show what you have described?
Why ask it
Moves the interview off recollection and onto documents you can obtain. Ask while the person is still cooperative, because the request is much harder to make later.
Who else would know something about this?
Why ask it
Placed here rather than at the end because names come more freely once someone has already given a full account. Ask for people on the edges: cleaners, drivers, neighbors, whoever locks up.
Who would tell me a different version of this, and what would they say?
Why ask it
Getting the person to describe the competing account in their own words tells you where they expect to be contradicted, which is usually the weakest point in what they have told you.
What do you think I am going to find when I check this?
Why ask it
Offers a last chance to correct the record before contradictory evidence arrives, and often produces a voluntary disclosure. Keep the tone flat, because delivered as a threat it just shuts the interview down.
Is there anything you are holding back, and if so, what is stopping you?
Why ask it
The reason matters more than the content. Fear of a third party, embarrassment and legal exposure need three different responses, and only one of them is a further question.
What do you think caused this?
Why ask it
Speculation is not evidence but it is a good guide to where to look, and it exposes what the person believes about everyone else involved. Record it as opinion and label it that way.
If you had that day again, what would you do differently?
Why ask it
Regret often carries a fact with it, usually something the person has not been asked and would not volunteer. It also tells you what they think they are responsible for.
What have I not asked you about?
Why ask it
A better closer than asking whether anything else should be added, because it puts the omission on the interviewer. It routinely produces the one detail no prepared question would have reached.
Running the interview
Practical guidance for the conversation itself
Why the order matters
An interview has one free account in it, and you get it near the start or not at all. Open in ordinary routine, invite the whole story without interruption, and write your follow-ups down instead of asking them as they occur to you. Only when the account is complete do you move to timing, position and sightlines, then to the reliability tests in questions 9 through 11, then to corroboration. Asking the reverse-order question early wrecks the account you have not yet collected. Asking what somebody is holding back before they have told you anything reads as an accusation and shuts the rest down.
Practical technique
- Stay quiet for a beat after an answer ends. People commonly add the most useful sentence into that silence rather than into a question.
- Ask what happened, not whether something happened. Yes-or-no phrasing tells the person which answer you expect.
- Never supply a detail you have not been given. Once you name the blue car, the blue car appears in later accounts and you cannot tell where it came from.
- Take the time claim apart every time. How they know the time is more useful than the time.
- Write down the exact words for anything you may quote. Paraphrase is where accounts drift.
- Fix the next contact before you leave: what you will send, what they will look for, and when you will speak again.
Reading answers without overreading them
Nerves are not guilt
Fidgeting, poor eye contact and inconsistent detail are common in people telling the truth under stress, particularly if they are frightened of you or of someone else. Treat behavior as a prompt to ask more, never as a finding.
Accounts that are too smooth
Real memory is patchy and self-correcting. An account delivered in clean chronological order with no hesitation has usually been told several times, which is worth noting without assuming why.
Where inconsistency actually matters
Peripheral detail shifts between tellings in almost everyone. What matters is a change in the central sequence, or a detail that appears only after you have revealed what you know.
Separate observed from inferred
Witnesses report conclusions as if they were observations: he was angry, she was leaving. Ask what they saw that led to that word, and record the two things separately.
What goes wrong
Contaminating the memory
Showing a photograph, naming a suspect or describing the scene before the account is given can permanently alter what the person recalls, and there is no way to undo it afterward.
Interviewing witnesses together
Two people in one room produce one merged account, usually the more confident person's. Separate them and separate them early.
Committing to a theory
Once you have a preferred explanation, your questions start collecting support for it. If you notice you have stopped asking things that could disprove it, the interview has become a confirmation exercise.
Getting the legal footing wrong
Cautions, the right to representation, recording consent and the limits of your authority differ by jurisdiction and by whether this is a criminal, employment or journalistic enquiry. Get that settled before the first question, because an otherwise good interview can be unusable.