David
W. Szymanski, Ph.D.
Department
of Geological Sciences
Forensic Scientist
Volcan Irazu,
What I do…
Forensics
Research – Trace Evidence Examination
One of my areas of research in forensics focuses
on the use of Laser Ablation Plasma Mass Spectrometry (ICP-MS) to discriminate
between float glass fragments by their elemental composition.
Glass is a common kind of trace
evidence. Because it is found almost
everywhere in society (automobiles, homes, businesses) and because it is so
fragile, glass is often broken and transferred during the commission of
crimes. Very small glass fragments can
be important evidence in homicide, burglary, rape, assault, and hit-and-run
cases. Like most trace evidence, the
goal of any glass analysis is to support the conclusion that two glass
fragments (the known and the questioned) either could have come from the same
source or did not originate from the same source. In rare cases where a fractured edge of two
glass fragments fit together like puzzle pieces, the "fracture match"
is proof that the two fragments were once adjacent, thus have the same source.
Traditionally, most glass comparisons have
been done using properties such as color, thickness, density, and refractive
index, or the ratio of how light moves through a material versus how it travels
through air. Of these, refractive index
(RI) has been the most-employed and most useful technique. However, due to improvements in the way glass
is manufactured, RI measurements for many glasses can be very similar within
the accuracy of our measurement. A
smaller class of measurement is the chemical composition of the glasses. In glass, many "trace" elements are
highly variable. Two different glass
fragments, even if they have similar RI values, may be discriminated by their
trace elements they contain. Using a
laser, a very small part of a glass fragment can be ablated, or heated up
violently to the point that it breaks into ultra-small pieces, and then analyzed
by a mass spectrometer. The mass
spectrometer then gives a count of each element selected. These numbers can be used to compare two
fragments, leading to a conclusion based on their similarities or
differences. We do these analyses
regularly in the ICP-MS laboratory at Michigan State University.
Along with other methods, I apply this
technique in the analysis of trace evidence for
Forensic Science Consultants, Inc.
in
There is more coming to this page soon,
including information on recent forensic collaboration projects and pictures
from meetings of the Midwestern Association of Forensic Scientists.
Geology Research –
Igneous Petrology, Geochemistry
My graduate work in geology has focused
on the origins of silicic igneous rocks, both intrusive and extrusive. My Master’s research (structural geology) was
on emplacement of the Little Cottonwood granodiorite pluton in the
Forensic
Science Consultants 1099 Phone: 517 974 7303 CONTACT ME: Department
of Geological Sciences 206
Natural Science Building Phone:
517 432-3100 x.138 Fax:
517 353-8787