THE ONLY CLUE A latent print found in dust may be the only clue when there are no other leads. Because areas that are routinely touched by the victims are not normally dusty, a dust print that is found may be the only link between the perpetrator and the crime scene. However, latent prints in dust are a nightmare. A latent print is left in dust when the dust is removed by adhering to the ridges of the skin that touched it. In order to avoid having to reverse photo negatives or use a liquid lifter, another evidence technician and I worked to find an easier, simpler method of obtaining these extremely important latents. After a lot of time and effort -- and countless experiments -- we developed a quick and easy way to collect and compare fingerprints left in dust. This technique has been taught in law enforcement schools throughout the state of Texas and in the FBI Academy in Quantico, Virginia.
THE SOLUTION To remove a latent print in dust, simply place a clear piece of wide fingerprint tape over the print and apply with very slight pressure. After lifting the tape from the surface, you can hold the tape in front of a light source to see the lifted latent dust print. Note that the friction skin ridges will not be seen as well as the friction skin furrows. The dark lines that you see will not be the dust taken from the surface by the friction skin ridges, but that which was left behind by the friction skin furrows. The tape should be placed sticky side down over the top of an ordinary styrofoam cup. Because wide tape is used, the print will be sealed and well-preserved inside the styrofoam cup without fear of damage or contamination. The remaining process is also relatively simple. When you are ready to proceed with the examination of the print, simply cut off the bottom of the styrofoam cup and discard it. Then place a black card or black sheet of construction paper on the bottom of the upper half of the styrofoam cup to create a black background for the print. Place it under a camera with direct lighting. The inside of the white styrofoam cup will create bounce lighting, which will help to balance the light for your photograph. You may need to play with the lighting and/or exposure, just as you would any other latent photography in order to achieve the best picture. By using black-and-white film and black background, the pictures will produce a latent dust print with the black lines representing the friction skin ridges. The white lines of the print are caused by the dust that is left by the friction skin furrows adhering to the fingerprint tape. Again, keep in mind that when using this method, the photograph of the latent dust print will show black ridges and white furrows. After you have finished photographing the latent dust print, preserve the print by placing it (cup and all) inside another styrofoam cup, and seal it with tape.Before trying this technique at a crime scene, it is a good idea to practice on a latent dust print of your own, as there is no such thing as a “second” lift of a latent dust print. Practice is necessary in order to get a feel for the best pressure of the tape, as well as to learn how to take the best picture when you photograph the print in the styrofoam cup. My hope is that all investigators and crime scene technicians can learn and use this technique in their battles against crime.