Abstract: The recovery of a developed latent print from the inside of a compound curved surface can be accomplished with flexible casting materials.

Introduction

Latent prints are sometimes developed on surfaces that are not able to be easily photographed (e.g., the inside of handles of glass or china, or other fragile items with handles). Removing (or attempting to remove) the handle to photograph a developed latent print on the inside of the compound curved surface could result in damaging or destroying the developed latent print. However, the recovery and photography of the developed print can be accomplished without removing the handle through the use of flexible casting materials (e.g., Mikrosil, Durocast, or Coe Flex).

Technique

A white ceramic coffee cup was used for this study (Figure 1). The evidence was subjected to vapor phase cyanoacrylate fuming. A f luorescent dye was applied to the cup, and the developed latent print was visualized with a forensic light source. The developed latent print was on the inside of the cup's handle, making evaluation and photography very difficult.

The area of the print was dusted with a fingerprint powder that was selected to contrast with the casting material to be used. Two-part casting material was mixed according to the directions. The mixed material was then thinly spread over the area of the developed latent print and allowed to set up or harden (Figure 2). The resultant cast, upon removal, retained the shape of the object to which it had been applied (Figure 3).

As in all lifts of this type, the developed latent print in the casting material was laterally reversed from its deposited position. Two methods can be used to properly record the developed latent print.

First, the lift can be photographed and then the negative can be printed in reverse. This reverse photograph will put the lifted impression in a natural or correct position. The second way of reversing the lifted impression is to scan the impression or photograph into a software program and then invert the image.

The cast was carefully mounted on a piece of glass to flatten the casting material containing the impression of the developed latent print. The cast was secured to the glass plate with cloth duct tape (Figure 4). The glass plate was supported from underneath so that the glass plate was parallel to the film plane (Figure 5). It was photographed using a Polaroid MP-4 camera with Polaroid #665 PN (positive and negative) black and white film. This film provides a negative that can be used to print the lifted developed latent print in its correct position, and the photographic negative usually has better detail and contrast than the Polaroid positive. The photograph positive will be in reversed position (Figure 6).

A scanner was also used to record the lift and then to correct the lateral reversal. The lift was attached to a piece of clear acetate (sheet protector) to ensure f latness and minimal change of distance between the lift and the cathode tube. Scanning was done at a resolution of 1000 ppi, and the image was saved in an uncompressed file format. The image (Figure 7) was imported into image editing software (Adobe Photoshop) and was inverted to the correct lateral position (Figure 8).

Silly Putty

The application of Silly Putty (purchased from a toy store) was also investigated. Silly Putty required no preparation other than to flatten a suitable quantity into a usable form. The material adequately removed the image of the dusted print; however, the elasticity of the material made it difficult to remove without stretching, which resulted in distortion of the developed latent print.

Conclusion

The use of flexible casting materials commonly employed to record tool mark impressions has an appropriate and valuable application in the recovery of developed latent prints. The technique is particularly useful on irregularly shaped surfaces and in difficult locations. This recovery technique should be practiced prior to actual casework.

The use of materials and techniques commonly used in other disciplines of forensic science should be examined for application to other disciplines.

For more information, please contact:

Eugene R. Czarnecki
Criminalist
Iowa DCI Criminalistics Laboratory
Wallace State Office Building
Des Moines, IA 50319
(515) 725-0517
czarneck@dps.state.ia.us

Figure 1
A white ceramic coffee cup.

Figure 2
Mixed casting material spread over the developed print.

Figure 3
The cast retained the shape of the object.

Figure 4
Flexible cast is flattened and attached to a glass plate.

Figure 5
Glass plate was supported so that the plate
was parallel to the film plane.

Figure 6
Photograph of print.

Figure 7
Scanned image.

Figure 8
Reversed image for proper comparison orientation.

*From the Journal of Forensic Identification Vol. 53, No. 5, September/October 2003
The Official Publication of the International Association for Identification
"Reproduction of the Journal of Forensic Identification, in whole or in part, for noncommercial, educational use is permitted provided proper citation of the source is noted. Reproduction for any other use is prohibited without prior written permission. Requests for permission may be addressed to the editor (of the Journal of Forensic Identification -- jfieditor@theiai.org)."

Article posted: September 11, 2007