Use of nitrogen cryogun for separating duct tape and recovery of latent fingerprints with a powder suspension method.

Duct tape is sometimes recovered as physical evidence in crimes. The purpose of this study was to determine the quality of latent prints on the adhesive and non-adhesive surfaces of duct tape samples that were separated using three methods. Three hundred donor fingerprint impressions were deposited on duct tape. Sections of duct tape were affixed to sections of cardboard and a fingerprint placed on the non-adhesive surface of the tape. A second layer of duct tape was prepared and a fingerprint placed on the adhesive side of the tape and then the tape was affixed to the piece of tape on the cardboard. After a 24-h period, the samples were separated using gradual force, liquid nitrogen applied with a cryogun and an adhesive neutralizer to separate the layers of tape. The recovered fingerprints were processed with a fingerprint powder suspension method. The recovered fingerprint images were evaluated and rated as +1, +2, or +3. The liquid nitrogen spray separation method yielded the highest number of +3 prints.