l~testimo // Purpose of Tape Analysis Tapes Maureen J. Bradley, Ph.D. Federal Bureau of Investigation Chemistry Unit ,,-

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1 i ". i. he Forensic Analysis of Pressure Sensitive Adhesive Tapes Maureen J. Bradley, Ph.D. Federal Bureau of nvestigation Chemistry Unit! // Purpose of Tape Analysis to conclude with the greatest possible certainty whether or not a "suspect" sample can be associated with a "known" sample (common source) to provide lead information to investigators when a source has not been identified 1 Li' Role of the Laboratory Examination of Evidence Technical Advice Court Testimony Training m Forensic Science Defined as the application of science to criminal and civil laws that are enforced by police agencies in the criminal justice system. ii ' i l~testimo nial Evidence Oral depiction of facts by a witness under oath ~Testimonial Evidence - Ordinary or lay witnesses give testimony on events or observations that arise from personal knowledge. -Expert witnesses are called upon to evaluate evidence that the court lacks the expertise to do; he or she may then express an opinion as to the significance of their findings.,,- 313

2 ll -"f scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of opinion or otherwise." - Rule 702, Federal Rules of Evidence Expert Testimony The opinion of the expert is based on a reasonable degree of scientific certainty derived from experience and training. The expert is not an advocate of either party's cause, but rather an impartial scientist. The expert's opinion may be accepted or ignored during jury deliberations. ~ FB Laboratory Statistics il > 600 employees --200,000 items of evidence J received each year --550,000 examinations conducted. each year ~ Contributors FB field agents Local law enforcement State law enforcement US territories Foreign countries Chemistry Unit Toxicology General Chemistry Paints, Tapes, and Polymers! ~ Paints, Tapes and Polymers Approximately 200 cases per year ---50% paint evidence ---30% tape evidence ---20% polymeric evidence 314

3 i// Types of Tape Evidence Duct tape Electrical tape Packaging tape Others // Protocol for Examination of Tape Evidence Visual and microscopic observations Physical measurements nstrumental analysis ~ Visual and microscopic observations ~ 'Physical measurements,i Type of tape Backing and adhesive color Texture of backing -calendering marks, gloss vs. matte f fiber reinforcement present, - pattern of weave Yarn count Width Thickness (overall and backing only) p, ~' nstrumental Analysis i/ ; FT-R Microscopy ', 'L nfrared (FT-R) Microscopy. Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDS) X-ray Diffractometry (XRD) Pyrolysis Gas Chromatography/ Mass Spectrometry (py-gc/ms) Polarized Light Microscopy (PLM) Backing - Type of material impregnant, plasticizer, release coat, etc Adhesive [ - Type of rubber Some filler, pigment, and plasticizer information Fiber Reinforcement - Type of fiber -,~':i 315

4 B Utility of SEM Structural maging Elemental analysis Elemental distribution maps Chemical imaging ~i~j~ij~!i! ii~ii~i ~i~i~i~j~i~jil i!~! m/~rj~~nm~ ',. ~.".~, m SEM/EDS Backing - Elemental analysis - Topographical analysis Adhesive - Elemental analysis XRD m py-gc/ms Provides crystalline information of pigments, fillers, and film -CaCO 3, TiO 2, Clays, ZnO, etc. - Pyrolysis - degradation of materials in an inert atmosphere. Converts cured, insoluble materials to gaseous phase -Gas Chromatography- separates components based on their size, affinity for column, etc. -Mass Spectrometry-identification of components based on their mass ~:" il, "}~! py-gc/ms Further classification of rubber component(s) Further classification of polymeric film backing Determine other organic components, ie) plasticizers, impregnants, etc. ~ Purpose of Tape Analysis to conclude with the greatest possible certainty whether or not a "suspect" sample can be associated with a "known" sample (common source) to provide lead information to investigators when a source has not been identified 316

5 k. ~ Sample Conclusions Based upon the examinations conducted... -"...Q1 is different from K" -"..Q1 and K1 are similar in composition.. " -"..Q1 is consistent with having originated from K1, or a source of similar manufacture" -".. Q1 originated from specimen K"! t~,,:. :!>'~.;:.'..;.!~'?.:t:~..,!~ (~:t:,:: Duct 7~.pe Con~ruction FLM CLOTH ADi4EStVE :~ : : " :.,. i',~..:...~... ~.,~,,,.,~,;,..,~,,;... :~:~.~;:`...;.~.~.:.`...1.;~..`..`...~:~;~.:~.~..`:~.~:~.`..`~;,~`~;~:`~.`..~:~:.~.`~`~.~`~... Cry~,:tai~!~#, ~oly 4d'ir',,orovi(Jes ilo.~igt~.~ie,~s, l e~-..sit.(." str~.:.l.'~flth, w~.'~ter res!stia~.~(~,~ Polyethylene (PE) Backing - Color / Print / Embossed surface / Film markings - Thickness: <2 mil, low-end; >2 mil, construction - Width // Polyethylene (PE) Backing - FTR and py-gc/ms data is straightforward - SEM / EDS principally A- occasionally observe fillers present in the PE film -XRD confirms identification of crystalline materials in the film (talc, CaCO 3, clay) / Scrim Fabric - Pattern of weave - Yarn Count 20X10 low end, commodity, retail 1! 24X16 craftsman, painting & HVAC 38X24 industrial, specification grade i/ Scrim Fabric - Type of fibers (Polyester (PET) and/or cotton) Ratio of each can vary by product (50:50, 65:35) Fiber shape and diameter can vary - UV fluorescence 317

6 ....., 1-.. Adhesive -Rubber components (FT-R, py-gc/ms) Natural rubber (cis-polyisoprene) reclaimed rubber - Filler and pigments (FTR / SEM / XRD) clay, CaCOs, TiO2, ZnO Analysis of Electrical Tape Backing: Polyvinyl Chloride (PVC) -Color, width, thickness - Glossy vs matte -Light Microscopy- film markings oblique lighting metallized coating (A), reflective light Analysis of Electrical Tape Backing: Polyvinyl Chloride (PVC) - FT-R - SEM/EDS Topography and elemental analysis Sb, Pb, Si, A - py- GC/MS HCl, plasticizer(s) -Solvent extraction - GC/MS - identification of plasticizer(s) M Analysis of Electrical Tape Adhesive - Color - FT-R / py-gc/ms Polyisoprene or SS Carbon black, plasticizer(s) - SEM/EDS S, Br, C, Pb, Si ll ~~~,nalysis of Packaging Tape Types include: -Biaxially oriented polypropylene (BOPP) - Monoaxially oriented PP (easy tear) - Strapping tape Physicals: -Color of adhesive and backing - Thickness, width 318

7 .,., :..-, Dnalysis of Packaging Tape Backing- Generally Polypropylene - FT-R -SEM -PLM -interference colors Adhesive- NR, acrylic, SS - FT-R - SEM/EDS - py-gc/ms i Other Types of Tape ncountered in Case Work Masking tape -vary in width, color, crepe, impregnantand adhesive formulations Gaffer's tape -w/f, color, adhesive formulation! Other Types of Tape ncountered in Case Work Foil tape -release liner, aluminum purity Medical tape Friction tape ~" li "~'-- The most probative value of some of these unusual tapes is that they are not commonly seen and therefore may provide some information regarding the perpetrator's profession, hobbies, etc. 319