Analysis of Small Particles Adhering to the Edges of Duct Tape as a Means to Make Associations in a Way that is Independent of Manufactured Characteristics

This project will determine if very small particles(VSP), acquired post-manufacture and trapped in the adhesive along the edges of duct tape rolls, can discriminate among tape segments from different rolls and provide a quantitative association between segments from the same roll.

Forensic analysis of duct tape is important in the investigation and prosecution of major crimes where it occurs as blindfolds, bindings, and ligatures. Laboratory methods of examination and comparison are focused on physical and chemical properties of tape backings, adhesives and reinforcing materials. Correspondence in properties provides very strong evidence that two specimens share a common manufacturing source. However,as for any mass-produced commodity, the associative value is limited to a class association. This concern was specifically identified in the 2009 NAS report, together with the suggested remedy that analytical methods be developed to exploit characteristics acquired post-manufacture, during an item’s use.

Once a roll of tape is put into use, exposed adhesive along the sides of the roll presents an ideal opportunity for collection, and most importantly retention, of the VSP that are ubiquitous in our environment. VSP occur with tremendous variety and, when adhering to items of physical evidence, can provide a powerful means of association that is independent of manufacturing characteristics.

This project will (1) develop a practical and effective means to harvest VSP that are trapped within the adhesive along the edges of duct tape,(2) harvest VSP from the edges of a population of duct tape specimens, sufficient to test their potential to address the 2009 NAS concerns and support or refute the association of one piece of tape with another, (3) use SEM/EDS and particle combination analysis to analyze these VSP and distinguish particles acquired post-manufacture from those present as manufactured components of the adhesive, and (4) use previously developed statistical and interpretive methods to measure the discrimination and potential evidential value that can be provided from VSP acquired post-manufacture.

Project results will provide (1) new methods for analysis of post-manufacture characteristics of duct tape, (2) contributions to the larger NAS recommendation to develop methods for exploiting characteristics acquired post-manufacture, (3)further development of NIJ-sponsored research into quantitative trace evidence associations based on VSP, (4) characterization of duct tape adhesives based on populations of individual particles, and (5)a foundation for follow-on research into prototype casework applications for tape and other adhesive materials that accumulate VSP post-manufacture.

Note: This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14). CA/NCF