Invisible Fingerprints: CSI Style!

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Updated on Feb 06, 2012

Grade Level: 5th - 8th; Type: Physical Science

The project is a fun and safe experiment used to develop latent fingerprints on a common retail receipt also known as thermal paper. This technique is a common experiment used by forensic officers throughout the world.

  • What is forensic science?
  • Why would anyone need to find fingerprints on paper?
  • What is thermal paper and where is it used?
  • What are amino acids?
  • What is Muriatic Acid?

This experiment is a simple and reliable method for detecting fingerprints on a receipt. The results are very magical for students to witness and the experiment can make the student feel like a real, life CSI.

  • Muriatic Acid- found at your local hardware store
  • Fish tank or clear container
  • Receipt from your local store

  1. The student must run their hand through their hair to obtain natural oil on their fingers.
  2. The student will then handle a receipt and place it in a covered fish tank or container.
  3. A small amount of muriatic acid is placed in the tank within another small container.
  4. After several minutes, the fuming reacts with the amino acids in the oil and the fingerprints appear in a clear, green form!

Take before and after photos to illustrate the experiment much like a real court presentation.

Terms/Concepts: Forensic Science; Muriatic Acid Fuming; Thermal Paper; Amino Acids

References:

Detective Constable Jake Friesen is a member of the Forensic Identification Unit with the Peterborough Lakefield Community Police Service in Ontario, Canada. Jake is highly trained in many disciplines of forensic science and is a fingerprint expert in Canada.

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