Content

• To step
• Part 1 of 2: Making fingerprints
• Tips
• Necessities

Making fingerprints for a crime investigation requires a precise technique. A smudge or blank area on the printout can render computer analysis worthless, or obscure details required to identify a suspect. If you have questions about a specific, unusual situation, try to find the guidelines of your specific agency or institution, or the service to which you will be sending the prints. If you want to do fingerprints for fun, use a pencil and a piece of tape.

To step

Part 1 of 2: Making fingerprints

1. Prepare a fingerprint card. You can print fingerprint cards from freely available online images. Check out this website used by the FBI and other US government agencies. Place the card on a special surface or simply hold it in place with a heavy object to prevent it from sliding.
   • If you are going to take fingerprints for an official purpose, you may need to find a fingerprint card that you can use. Even if your government agency is allowed to use the card indicated above, the agency must apply for the card according to these instructions.
2. Clean your hands. Make sure the person has washed and dried their hands to remove any dirt that could obscure their fingerprints. Check your hands for fibers on the towel, and if so, ask him or her to brush them off. If soap and water are not available, rubbing alcohol is the next best option.
   • Ask the person to sign the card for hand washing. Use a pen with blue or black ink.
3. Take the person's hand. The person is not the one using the fingerprint card. You as the person taking the fingerprints do this for him or her. Hold the mouse over the person's thumb, keeping the other fingers under your hand. With your other hand, hold the person's finger just below the tip of the nail and by the third knuckle.
   • Keep the wrist level with the hand. If possible, move the fingerprint station to a height equal to the person's arm.
   • Ask the person to look away if they appear to be trying to "help" - the fingerprint will be clearer if only you are the one leading the hand.
4. Note parts of the fingerprint that are missing. If there is any reason why the whole fingerprint cannot be taken, please make a note of this, otherwise the card will be rejected. Usually the reason is "fully amputated", "fingertip amputated" or "missing from birth".
   • Extra fingers are not saved by the security service. Other security services may require extra finger prints to be placed on the back of the card. Try to find the specific guidelines for your purposes.
5. Deal with tricky fingerprints. Many people who pursue a particular profession or hobby have their fingerprints fading over time. If the fingerprints do not appear clearly on the print, try one or more of the following techniques:
   • "Milk the fingerprint" by applying pressure or rubbing the finger in a downward motion, from palm to fingertip, before taking the impression.
   • Rub fingers with worn lines with hand lotion or a cream.
   • Hold ice to the finger, dry it and take the impression. This works best on naturally fine lines and soft hands, not worn finger relief.
   • Use very little ink and very little pressure.
   • Pay attention to the condition of the prints, especially if the skin is worn smoothly. Write down the appeal that led to this fingerprint problem.
6. Fill in the complete card. Your card will likely be rejected if any information is missing. Use blue or black ink to fill in each box. If you are unsure of what to enter in each box, ask someone with more experience or search online for the guidelines of the relevant service. Even the "Weight" or "Date of Birth" box should be filled in in an exact format to keep the database consistent.
7. Analyze the fingerprints. Get familiar with the basics, and you'll be more likely to notice fingerprint issues. Here's a first lesson:
   • 95% of all people have fingerprints with loops (grooves that make a curved u-shape) and / or loops (circles). The rest are arcs, with grooves that come up and bend or peak, and then move on instead of curving back. Make sure to bring enough of the printout to identify which type you are dealing with.
   • "Delts" are any point on a fingerprint where grooves meet from three directions. If you don't see at least one in a loop, or a squiggle, make sure you've included the entire fingerprint. It is rare that a delta is not visible, in which case you write "no delta, inked nail to nail" on the card.

Tips

• Some deformed hands require a special technique. Roll the ink directly onto the fingers, wrap square sheets of paper around it, then tape it to the card. Record the deformity in the appropriate place.
• Store Porelon ink pads upside down for longer life.

Necessities

• Ink pad for fingerprints (or other device - see instructions)
• Fingerprint card
• Water and towel
• Blue or black pen