Effects of Adhesives on the Subsequent Instrumental Analysis of Various Trace Evidence

Abstract

A central pillar of forensic science is the proper collection and containment of evidence. Technicians at both crime scenes and within the labs are reliant on a variety of adhesives to accomplish this task. As collection devices, adhesives come into direct contact with evidence such as fibers and paint. This contact introduces a possible risk of either physical or chemical interference. Contamination may have dire consequences in the courtroom therefore, any area of risk must be investigated with the utmost sincerity. The idea that these adhesives may alter paint evidence, and paint evidence alone, during collection from a scene and subsequent storage has been codified into both NIST and SWGMAT standards. Neither committee, however, has concerns regarding adhesive use during fiber or other trace evidence collection and no articles have thus far been discovered that prove any chemical or physical interactions between trace evidence and adhesives. This thesis\u27 goal was to investigate if adhesives have a chemical or physical impact on the trace evidence, and whether these differences can be observed during laboratory examination. In this study, six distinct adhesives were utilized to test for their potential chemical or physical impacts on trace evidence. To simulate common trace evidence three diverse types of fiber evidence, as well as three different types of paint evidence were collected. All adhesive and evidence combinations were stored at four different storage intervals, 1 week, 4 weeks, 14 weeks, and 24 weeks and chemical and physical changes were documented by Fourier Transform Infrared Spectrophotometry (FTIR) using an Attenuated Total Reflectance (ATR) objective. The results showed that the rate of physical alterations and chemical contamination created two groups. One with a larger amount of both physical damage and chemical contamination: forensic tape, packing tape, and hinge lifters. The other group with less: gelatin lifters, sticky notes, and lint rollers. Overall, between the fiber and paint samples there does not seem to be an experimental reason why adhesives should not be used on paint trace evidence. These results could open the door for practitioners to use weaker adhesives for both collection and storage of trace paint evidence