Inkless Fingerprinting

Introduction

Biometrics, automated methods used for the recognition of individuals based on their unique physical characteristics, are being employed in all types of security devices. These include those for voice recognition, retinal scans, or facial structure. Although established long ago, the fingerprint remains one of the most important and useful pieces of biometric information in any forensic investigation. No two people have the same fingerprints, not even identical twins. This uniqueness allows fingerprints to be used as evidence for the identification of individuals at crime scenes, accidents, or to identify “John Does.”

Concepts

• Fingerprint analysis
• Forensics

Background

Law enforcement officers use AFIS (the Automatic Fingerprint Identification System), a database of fingerprints of anyone who has ever been arrested or required to provide fingerprints for other reasons, such as the purchase of a weapon or renewal of a driver license. Most searches of this database take less than 10 minutes to obtain a fingerprint match. There is a great success rate of matching fingerprints in the AFIS database because many of the people who commit crimes are criminals with previous arrests. Booking sheets of fingerprints are scanned into this database today. Booking sheets were formerly created by inking the fingers and placing each inked digit (finger) in an appropriate square on a sheet of paper. It was a very messy experience. Inkless fingerprinting eliminates the mess associated with traditional fingerprinting techniques and is much more time efficient.

Materials

Safety Precautions

Remind students to wash hands thoroughly before leaving the laboratory. The color former in the activator pad acts as an antibacterial and is completely nontoxic and residue-free.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Stickers and activator pads may be disposed of according to Flinn Suggested Disposal Method #26a, in the regular trash.

Procedure

1. Distribute one sticker at a time from the dispenser by holding the box by the narrow dimension and pulling the tape. The stickers pop up one at a time with no ripping, tearing or waste.
2. Place one of the chemically activated stickers in each space on the Booking Card to correspond with each finger to be printed, as directed by the teacher.
3. Using the right index finger (digit) or other digit as instructed by the teacher, gently press the activator pad.
4. With light pressure, tap the digit one time onto the corresponding chemically activated sticker. Note: A bright blue fingerprint should develop instantly on the sticker. There is no ink or residue to stain skin, clothing or other objects and once developed, the fingerprint will not smudge.

Student Worksheet PDF

12503_Student1.pdf

Teacher Tips

• This kit contains enough materials to obtain 500 fingerprints.
• The color former on the activator pad is colorless and will not stain or smudge.
• The sharp, clear, permanent print will appear on the sticker instantly. If the print is too heavy (smudged or smeared) or too light (pinprick), simply place another sticker over the bad print and try again.
• Copy the Booking Card onto card stock paper to simulate an FBI-type fingerprint card.
• The Booking Card may also be used with an ink pad to make traditional prints.
• The Inkless Fingerprinting Kit is easily incorporated into any existing forensic unit or may be used as a stand alone activity.
• When making a print, the key is to lightly tough the sticker. If the touch is too heavy, the print will not be crisp.