Published by Daniel Jenkins for 5 Minute Detective. How we make the site.
Someone says they were elsewhere. Does the evidence cover the whole time that matters? A missing recipe card helps you check.
An alibi is a claim that someone was somewhere else when an event happened. To check it, you need to know where they were and for how long.
“Someone saw me that evening” leaves a lot of time unaccounted for. A weak alibi does not prove guilt. It means you still need to check what happened.
Ask four clear questions
First, find out when and where the event took place. Then check whether the alibi covers that place and the whole time that matters.
- Who was seen? Does the clue clearly show the person, or just a coat or a voice?
- Where were they? Could they still reach the place where the event happened?
- When were they seen? Does the clue cover the whole time, or just one moment?
- Who can back this up? Did someone see it, or are they repeating what the suspect said?
Check what the person needed to do. Being away from a room may rule out carrying something from it at that time. But the story might tell you that an earlier act caused a later event. Use that only if the clues explain it.
Example: a missing recipe card
A signed recipe card goes missing from a kitchen. A photo shows it on the counter at 12:02. At 12:08, the organiser finds it gone. We know someone had to enter the kitchen and carry it out between those times.
The dining room is a twenty-second walk from the kitchen. Nobody watches the corridor, and diners cannot see the counter. All the times below come from the same correct clock.
Scroll sideways in the table to read every column.
| Person | What they say and what we know | What this proves |
|---|---|---|
| Leah | “I was serving all through lunch.” A photo shows her at the dining table at 12:04. | She was there at 12:04. The photo tells us nothing about the rest of 12:02–12:08. |
| Omar | “I was outside.” A clear video shows him in the courtyard throughout 12:01–12:10. | He was outside the kitchen for the whole time when the card was taken. |
| Priya | “I stayed in the dining room.” Ben heard this from Priya. He did not see her there. | Priya has made a claim. Ben has only repeated it. |
Omar could not have carried the card out while he was outside on video. Leah could still have made the short trip before or after her photo. Ben's account adds no new proof of where Priya was.
This does not prove Leah or Priya took the card. It leaves them as people to check. We need another clue to work out who actually took it.
Ask how a witness knows
When two people tell the same story, ask how each knows it. Did they see it happen? Did they see a record? Or did one hear it from the other? A story repeated three times is still one story.
Two suspects might back each other up. That does not mean they are lying or that they are right. Ask exactly what each person saw, and for how long.
A false alibi is one clue
A clue may place someone in a room they deny entering. That shows a problem with their account. It does not explain why they went there or what they did. They might be hiding a different secret, or have the time wrong.
You may have a story you cannot check yet. Or a clue may show that story is wrong. Another clue may rule a person out. Keep these findings separate. Next, look for evidence of the act itself.
Try it: one clear photograph
A trophy is taken between 16:10 and 16:18. Someone could leave the lounge, take the trophy and return in two minutes. A photo shows Ellis in the lounge at 16:14. Nobody sees Ellis just before or after that, and the way to the trophy is open.
Does the photo rule Ellis out? Give one way Ellis could make the trip and still appear in the photo.
Show the answer and explanation
No. The photo shows one moment. Ellis could leave at 16:15 and return at 16:17. That two-minute trip fits after the photo and before 16:18.
This shows the trip was possible, not that Ellis made it. The photo still proves Ellis was in the lounge at 16:14. It cannot tell us where Ellis was for the rest of that time.
Things to remember
- Work out when and where the act had to happen first.
- Check who was seen, where, and for how long.
- Ask whether a witness saw it or only heard about it.
- A gap in an alibi is a question to follow up, not proof of guilt.
Use the facts in the story. If something is still unknown, leave it as a question.