Fingerprinting

What's it all about?

In the days before people discovered the value of fingerprinting to identify criminals, mistakes were made when innocent people looked similar to the real felons.

It is easy to take your own fingerprints, though it’s a bit messy with the ink! With enough care, you can find out what sort of fingerprints you have. You can also identify your friends from their fingerprint!

Find out more about fingerprinting at Fingerprints Totally Explained.

What is here?

You can:

• Download the Acrobat file on this topic (293K - this is identical to the one we use, including the students’ worksheets in colour), or
  

• View the notes below. These are divided into:
  Student notes
  Teacher notes
  Technician notes

Loop

Central pocket loop

Double loop

Plain arch

Tented arch

Plain whorl

Student notes

Latent prints

First take a latent (hidden) fingerprint. Press your right thumb on a sheet of glass or plastic film. Gently shake some talcum powder over your sweaty thumbprint, and blow off the excess. Make sure you don’t blow the talcum powder into your eyes. Smooth a piece of sticky tape over your thumbprint, then peel it off carefully. Stick the tape onto a labelled piece of black card. Hand it in to the Police Officer!

Fingerprint record chart

Collect a blank Record Chart (a simple version is shown below) and ink pad from the Police Officer. Roll your index finger lightly on the ink pad, then roll your inked finger onto the correct space on your Chart (you may have to practise this technique until you produce a clear fingerprint).  Repeat this method for each finger on your right hand. Wash your hand!
 

Fingerprint examination

Closely examine each fingerprint, and identify its pattern using the information sheets. Record this information on your chart.

Finally, work out whose prints belong to whom. Collect a labelled latent print. Look carefully to see if the labelled print is yours. If it’s not, work closely with your colleagues to work out which labelled print belongs to you.

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Teacher notes

This is easy to do, if a bit messy. Only a little talcum powder is needed to get a good result for the latent prints. Make sure that the reverse side of the black card is named, not the front as that would be a bit too easy! When the students use the ink pad, they should take care to roll their fingers across the paper, otherwise they will only achieve a black smudge. We found that it was surprisingly easy to work out whose prints belong to whom (unless they were cheating, of course). If you want to avoid cheating, the “Police Officer” should code the latent prints.

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Technician notes

In the lab:

Black ink pads (washable ink)
Rolls of clear sticky tape
Pieces of black card, approx. 10cm x 10cm
Pieces of clean glass (use propanone for cleaning)
Talcum powder
Hand lenses
Fingerprint Record Sheets

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