Did you know that every person has fingerprints with patterns unique to them? Fingerprints are left on everything you touch, even when you think your hands are clean.

Forensic science is the science that deals with collecting and analyzing evidence to ultimately solve crimes. Fingerprints are important in forensic science, because they can help identify who committed the crime. Remember: everyone has unique fingerprints.

There are three different kinds of fingerprints: patent, imprint, and latent. Patent prints are visible to the naked eye. You make these when your fingers are dirty, and you leave a fingerprint on a surface. Imprints are left on soft surfaces. You make these on soft surfaces, like when you grab a soft, wet bar of soap. Latent prints are invisible and need to be dusted for. You make these with clean hands on hard surfaces.

Your latent fingerprints come from the oils your skin produces every day, and the oils are what stick when you touch things. Like I mentioned earlier, you can dust for these prints. In fingerprint dusting, you use a powder that can stick to the fingerprint to dust over it and make it visible. Once you can see the fingerprint, you can lift it with tape and transfer it to a piece of paper. This paper is what gets sent to forensic scientists to be analyzed. There are other ways to make latent prints visible, but dusting is what we will practice today.

Although you leave fingerprints everywhere, the best prints are left on smooth and dry surfaces. You also leave better fingerprints when your fingers are wet and oily. We’ll be able to see this later.

 

You will need: a glass/ smooth surface, baby powder and black paper (if the surface is dark) or cacao powder and white paper (if the surface is light), a small bowl, tape, a brush with soft bristles, a cloth to dust with, water, soap, and lotion

 

Procedure:

  1. Put your powder in the bowl and wipe your surface with the dust cloth.
  2. Choose one of your finders to press on the surface. Can you see your fingerprint? If you can, what is the print from?
  3. Dip the brush into your powder so only the tips of the bristles are covered. Tap the brush with your finger to shake off extra powder.
  4. Gently brush the surface where you left your fingerprint. If you push too hard, your print can be wiped away! Can you see your fingerprint once you dust over it?
  5. After dusting, gently blow the area you dusted to remove extra powder. How does your fingerprint look?
  6. Take your tape and carefully press it onto the dusted print. Peel the tape off slowly and transfer your fingerprint to your paper. How does the print look now?
  7. Wash your hands with soap and water, put lotion on your hands, and repeat steps 1-6. How does this new fingerprint compare to your first one? Which print can you see better? Do you remember why?