Midwest Forensics Resource Center 2002 Funded Projects
Characterization of glass fragments is normally accomplished by measuring
the physical and optical properties of density and refractive index. However
further discrimination, such as identification of a suspected source of origin,
has become more difficult as the range of refractive indices has narrowed
within glass subtypes because of advances in glass manufacturing technology.
This project proposes to evaluate laser ablation-inductively coupled plasma-mass
spectrometry in order to determine the unique trace elemental signature or
fingerprint of glass samples, and to develop criteria and protocols for the
comparison and differentiation of glass fragments from different sources.
Final Report
This work would correlate the alloy analysis of various firearms to optimized forensic etching techniques used for the recovery of obliterated serial numbers. This recovery is facilitated by the selection on the most suitable etchant for any given firearm, based on an awareness of the alloy used. Beyond a superficial knowledge of properties of the samples, investigators typically are forced to experiment with an array of etchants, singularly or in sequence. This work will use a portable tool to generate a list of firearm alloy analysis, thereby guiding a criminologist to select the right etchant for a given firearm.
This work will generate guidelines and insight for the proper use of the
magnetic particle method as a forensic tool for the recovery of obliterated
serial numbers on ferrous samples. Practitioners of this method for nondestructive
inspection are well aware that a successful inspection will be the result
of using a magnetic field of appropriate magnitude and orientation, the correct
nature of the magnetizing current (AC/DC/rectified) and a suitable choice
of magnetic particle suspension. Investigators in crime labs currently use
this method in a manner that provides only sporadic success at best. It is
timely to remedy this situation.
Final Report
Figures for Report
Attachment to Report
Conventional techniques for restoring obliterated serial numbers are partially
destructive. Nondestructive alternatives are sought as they will allow the
subsequent application of other methods to the test piece and do not destroy
evidence in criminal cases. We propose a method based on an array of high-resolution,
high-sensitivity Hall or GMR sensor elements. The array probe will be used
to image the stray field that results from residual plastically deformed regions,
the remains of the imprinted serial numbers. Successful implementation of
the proposed technique will provide an efficient, nondestructive forensics
tool for recovering obliterated serial numbers without the need for surface
preparation or other processing.
Final Report
This project seeks to provide law enforcement officials with quantitative
data concerning the nature of tool affected surfaces. The work will involve
examination of surfaces using a combination of optical microscopy coupled
with quantitative measurements of the surface relief. The surface will be
examined optically and regions of interest identified for replication using
a simple technique. The resulting replica will be characterized using a two-dimensional
profilometer. The data will be statistically evaluated to ensure that the
replica accurately portrays the surface and, if so, attempts will be made
to identify an unknown sample by comparison to known samples. If successful,
this process should yield a forensic technique that is rapid, easy to perform,
and applicable to any shaped surface.
Final Report