日本語
The Security Camera That Ran Seven Minutes Fast (illustration)
FILE No.44Unsolved

The Security Camera That Ran Seven Minutes Fast

Difficulty ★★☆about 5 minTheft CaseTime offsetAlibis
The thief on the shop’s security camera shows "2:17," but the camera’s clock ran seven minutes fast.

Case Record

Late at night, someone broke into a jewelry shop. The security camera showed the culprit entering through the back door. The time display on the footage read 2:17 a.m.

But it was found later that this camera’s clock was 7 minutes ahead of the real time.

The four suspects’ alibis are as follows.

  • Akaishi: shopping at a convenience store from 2:05 to 2:20 a.m. (has a receipt)
  • Ito: on the phone with a friend from 2:00 to 2:12 a.m. (call record)
  • Ueno: at a bar, paying the bill and having another round, from 2:15 to 3:00 a.m. (bar record)
  • Endo: waiting at a hospital from 1:30 to 2:30 a.m. (reception record)
Your question

Who has no alibi at the actual time of the break-in?

Case Files

Evidence

Diagram

Early-morning hoursPersonAlibi spanAkaishi2:05-2:20Ito2:00-2:12Ueno2:15-3:00Endo1:30-2:30Footage time 2:17 (the camera clock is 7 minutes fast).
Diagram

Timeline

  1. The camera shows the break-in (really 2:10).
  2. The theft of the jewels is discovered.

Hints

If you get stuck, open the hints one at a time, in order.

Open hint 1

Is the camera’s clock ahead of or behind the real time?

Open hint 2

What is 2:17 on the footage in real time?

Open hint 3

Who has no alibi at that time?

Solve It

Your question

Who has no alibi at the actual time of the break-in?

Choose the answer closest to the truth.

Share: I'm solving this

The Truth

Ueno

The answer is Ueno.

The camera is 7 minutes fast, so 2:17 on the footage is really 2:10. At that time, Akaishi (2:05-2:20), Ito (2:00-2:12) and Endo (1:30-2:30) have alibis. Ueno’s alibi starts at 2:15, so he has no alibi at 2:10.

If you used the footage time (2:17) as it is, only Ito would lose his alibi, and Ito would look like the culprit. Correcting the clock offset is the key.

The real break-in time is 2:10PersonAlibi at 2:10AkaishiYesItoYesUenoNoEndoYes
Diagram of the solution

Key Points

  • Fix the "clock offset" in the record first
  • The time on the footage and the real time are different things
  • Check the alibis again with the corrected time

Why people get fooled

When a time is displayed on the footage, it is easy to assume "this is the correct time."

Similar tricks

  • The type that corrects a clock offset
  • The type that doubts the reliability of a record

If you like this file, try these

The Clock with Overlapping Hands (illustration)The Clock with Overlapping Hands★★★about 6 minCutting a Gold Bar Twice (illustration)Cutting a Gold Bar Twice★★☆about 5 minOver the Weight Limit (illustration)Over the Weight Limit★★☆about 5 minThe International Call Across Time Zones (illustration)The International Call Across Time Zones★★☆about 5 min
Previous caseNext case

If you view the truth, this case will not count as solved on your own. Open it anyway?
Privacy Policy (Japanese)

The cases on this site are fictional puzzles created for entertainment. Any resemblance to real people, organizations or events is coincidental.

© Unsolved Files