The Electro-static Dust Print Lifter
The Electro-Static Dust Print Lifter (ESDL) is a nifty little device to recover dusty shoe prints from a variety of sources including doors, carpeting, wood floors, paper, even human bodies! The devices have been around for a few decades and are pretty simple to use. Some people have even experiment with stun guns t generate the electrical current. The first ESDL models from the 1980′s were transported in a suitcase but many of today’s models are about twice the size of your smart phone. The theory involves introducing an electrical current through a thin sheet of metalized film. The current will attract the dust particles of the shoe prints transferring them to the film. The film is then photographed in a dark room to preserve the impression.
The process begins by locating an area you wish to test. Sometimes the CSI can see the impression with oblique lighting. Other times they may simply being sampling an area “blind” (such as the area in front of a bank teller booth after a robbery). A sheet of film (larger than the impression) is laid over the evidence. The bottom of a modern ESDL has both positive and negative posts (like a car battery) on opposite ends. The positive side is placed on the edge of the film and the negative end is set on a metal grounding plate. When the unit is turned on the current will travel through the film “sucking” it down onto the surface. A small rubber roller can be used to smooth out the film and eliminate any creases.
The total time needed to lift the evidence is just a few seconds. As with any electrical device there is a danger of getting shocked. If the CSI connects with any metal or wet surfaces they can get a real jolt. Nothing life threatening but it will definitely wake you up. The images below will demonstrate the basic steps involved.
Posted on June 16, 2011, in The Crime Laboratory, The Crime Scene and tagged Crime Scene, Electro-static Dust Print Lifter, ESDL, fiction, forensics, murder, mystery, thriller, tom adair. Bookmark the permalink. 6 Comments.