CasTips03 – Recovering Dust Impressions

By: Don Penven

Methods for Lifting Dust Print Impressions

Dust impressions are fragile at best, so the utmost care must be taken when attempting to lift them. Some methods work better than others, so it is suggested that you make several trial runs before going after the real thing.

1. Using adhesive materials to lift dust prints. Prior to the invention of the electrostatic dust print lifter, dust prints were recovered using adhesive-backed materials like tape.  Fingerprint lifting tape, especially the wide variety, does a fair job as a lifting medium. The widest latent lifting tape I am aware of is 4-inches. So it will be necessary to put down two lengths, side-by-side in order to retrieve a normal adult shoe print. If using 2-inch wide tape, use three or more strips.
   1. Use the tape in the same manner as when lifting latent fingerprints. Pull off a few inches of tape and tack down the end at one end or the other of the dust print to be lifted.
   2. Press the tape along its length to the surface using every effort avoid any air bubbles.  The tape should extend 2-3 inches beyond the beginning or end of the impression.  When the impression is covered, cut the tape with scissors and puck back about 1-inch (stick it to itself) because you are going to need something to grasp when you lift it from the surface.
   3. Add another length alongside of the tape on the surface and allow it to overlap the first tape by about 1/4 –inch along its length.
   4. Add a third and fourth strip if using a narrow tape (1.5 – 2-inches)
   5. You will need some form of backing material, preferably black in color, for mounting the tape. Most suppliers of fingerprint lifting tape also offer plastic backing materials.
   6. Slowly lift the tape(s) in one continuous motion.
   7. Attach one end of the tape(s) to the end of the backing material and slowly press it into place on the backer.
   8. The electrostatic dust print lifter eliminates the complications of the tape lifting process. A number of these devices have been available for several years. The one depicted here is unlike most competitive models since it does not require any wires or complicated hookup.
      1. Once the impression is located and photographed, a pickup mat is placed over the impression—black side down.
      2. The charging unit is positioned as shown below on the charging mat and metal ground plane
      3. When the charging unit is energized, it imparts an electrostatic charge to the surface, thus charging the dust particles present. These particles are then attracted to the charging mat.
      4. Turn off the charging unit and lift the mat from the surface. Note: Charging mats are supplied in 2’ x 3’ sheets, and they may be cut to smaller sizes when lifting a single dust print.
      5. The impression on the mat is photographed and then may be placed in storage/shipping boxes supplied by the manufacturer.

You may download the Technical Information Manual for the Electrostatic Dustprint Lifter HERE

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