Article: Toner Particles as Forensic Evidence
The Journal of Forensic Sciences is now offering an early viewing of a new article by Microtrace scientists. “Toner Particles as Forensic Evidence: Microanalytical Characterization of Known Toner and Recognition of Toner in Environmental Samples” is co-authored by Katie White and Christopher Palenik. This article explores the potential usefulness of subvisible toner cartridge particles as evidence in forensic investigations. The authors use a range of microanalytical techniques including light microscopy, SEM, and Raman spectroscopy to examine a variety of toner particles. They were able to demonstrate that these methods can help a scientist locate, characterize, and discriminate toner particles.
This paper was supported in part by a grant from the National Institute of Justice, Office of Justice Programs, U.S. Department of Justice.
“Toner Particles as Forensic Evidence: Microanalytical Characterization of Known Toner and Recognition of Toner in Environmental Samples”
Katie M. White M.S., Christopher S. Palenik Ph.D.
Journal of Forensic Sciences, 2020
Modern printing toners represent a prime example of subvisible particles that can be easily transferred to hands, clothing, and other surfaces. To explore the potential evidentiary value of toner particles, toner samples were collected from known printer cartridges and characterized by various microanalytical techniques to establish the properties most useful for recognition, identification, and comparison. Environmental samples (i.e., dust) were then collected from various locations at varying distances from toner‐based printers, using both tape lifts and carbon adhesive stubs, to assess the possibility of detecting toner. By light microscopy, toner can be recognized on the basis of particle size and shape, as well as color. Further examination of the micromorphology in the field emission scanning electron microscope reveals characteristic morphologies and differences in surface texture and shape among toner sources. Raman spectroscopy provides chemical identification of the pigment (or pigment class) and, in some cases, also permits identification of the polymer component. While black and blue pigment chemistry remained constant among toner varieties that were studied (copper phthalocyanine and carbon black), variation in yellow and magenta pigments was observed. Analysis of dust samples collected from various environments demonstrated that while toner is consistently detectable in close proximity to printers (within 2 feet), it also can be detected in dust collected in nearby rooms. This research demonstrates that toner particles can be located, characterized, and discriminated, using a suite of microanalytical methods that are applicable to forensic casework.