With increasing pressure on forensic scientists to provide detailed analysis of samples to help across a variety of challenges, there has never been a more important time for collaboration in the industry. Working closely with instrument manufacturers, forensic laboratories can get the highest quality data and ensure that they are able to process samples quicker than ever.
One laboratory has seen its work thrust into the limelight with its appearance on the popular Netflix show “Making a Murderer.” Using a combination of state-of-the-art instrumentation and techniques based on microscopy and microchemistry, Microtrace, a materials analysis laboratory specializing in the characterization and identification of small quantities and single small particles of unknown substances, works primarily in the forensics field, and is widely recognized for its work in providing evidence for high-profile cases.
The company’s father-son team of Skip and Chris Palenik have achieved a kind of celebrity status. Here, we talk to Chris about how the laboratory is using unique applications of Field-Emission Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (EDS) to solve the unusual problems routinely encountered in forensics.
Microscopy on the small screen
Skip founded Microtrace in 1992 and the company has since grown to 14 staff. The company keeps a wide range of databases and physical reference collections to consult—over 35,000 curated specimens ranging from sand, soil, glass, hair, pigments, dyes, food ingredients and more.
But more than accolades, Microtrace relishes the challenges sent its way and the opportunity to summon its vast expertise to let science determine the answers to the questions posed. These questions sometimes put the company in the public eye.
In the fall of 2018, the second season of “Making a Murderer,” aired on Netflix, showing Chris using a JEOL Field Emission Scanning Electron Microscope. In episode 7, he examined key evidence that may help the defense’s case for a mis-trial. Could the lead bullet fragment found in the garage of the defendant have passed through the skull of the victim, and were the particles embedded in the bullet fragment actually bone? After six months of waiting for a court order to release the evidence specifically for this purpose, the lawyer watched as the embedded particles in the bullet fragment were carefully examined in situ at the Microtrace lab in Elgin, Illinois.
Using SEM imaging EDS analysis, Chris found the particles to be wood, not bone, supporting the defense’s position that this was not the bullet that had killed the victim.
“Our work is based on solving a problem, often an unusual one, whereas a lot of labs work on processing huge volumes of samples in the same way. It is part of the reason we have had success in forensic cases. While we are ISO-accredited, we try to use creativity and a sample-driven approach to look at each individual sample and the question being asked to come up with best analytical path forward,” Chris said.
In addition to having analyzed evidence for several famous murder cases, Microtrace’s investigations have ranged from examining art, collectables, sports memorabilia, historical artifacts, geological samples, and industrial products.
“We do a lot of work for a wide range of industries helping them solve their problems, whether it’s foreign materials in their products or helping them understand the design of new materials,” said Chris.
Seeing through soils
With degrees in chemistry and geology from University of Chicago, and an MS and Ph.D. in geology from University of Michigan, Chris has a special interest in soil samples, and Skip has developed the analytical approaches to soil analysis used by most forensic science labs. The sample analysis is broken into different fractions, including the light mineral fraction and heavy mineral fraction. Polarized light microscopy (PLM), Raman and SEM EDS help identify the minerals in soil.
Chris conducted exploratory work looking at polished (and unpolished) grains with SEM, EBSD and EDS. In addition, markings on the surface of a grain can reveal a lot about the environment from where the soil or sand came. One case they investigated involved a shipment of cell phones that had been stolen and replaced with sand. By breaking down the mineral composition of the sand and consulting their reference collections, they were able to narrow down the port of call where the theft occurred.
A closer look with field emission scanning electron microscopy
Microtrace uses a field emission (FE) scanning electron microscope (SEM) as well as a tungsten SEM in its lab. The ultra-high resolution FE SEM (JEOL JSM 7100 FT FE-SEM) allows imaging at extreme magnifications. Most crime labs do not have this level of capability because a tungsten SEM is more affordable, and answers most of the “basic” questions in forensic science.
“The FE SEM allows us, when necessary, to look closer. Crime labs typically look at particles probably on the order of 10 to 100 microns on the low side, with the exception of gunshot residue (GSR) which analyzes particles as small as half of a micron. There is not much exploitation of evidence that is smaller than 10 microns. We look at that scale of evidence quite commonly, just about any material you can imagine, and in various cases we’ve applied SEM analysis to look at particles even smaller than one micron,” Chris explained.
Consequently, Chris says they are working on a grant developing nanotrace evidence for forensic science, and are looking at basic questions about scaling forensic analyses down further.
An ideal application for the FE SEM was to look for traces of lead articles in a military court martial case that involved the claim that a hole in a cotton-polyester blend shirt was caused by a bullet.There was little available data on what constitutes a bullet hole in fabric, so test shots were fired through a similar garment, which showed that the lead is captured, both on and in the surfaces of synthetic fibers that are stretched and melted from the energy transfer of a bullet tearing through a fabric at high speed. While GSR had already been identified by the prosecution from a sample collected near the hole, a closer look at the hole itself showed that severed fiber ends contained no detectable lead, and none of the synthetic fibers showed a melted texture. This demonstrated that the hole had not been made by a fired bullet. Further analysis of the severed fibers in the hole suggested that it might have been cut with scissors. This was supported when a surprise eye-witness came forward after hearing the scientific testimony and confirmed that he had watched the defendant cut the hole in the garment.
The future of forensics
As pressure continues to build on forensic laboratories to provide answers to a wide range of cases, advanced analytical instrumentation for precise analysis is critical. With forensic evidence often leading decisions in high profile court cases, the future for companies like Microtrace remains optimistic.
“We believe that with each scientific challenge we meet, we become still better prepared to solve the next problem that comes to us,” Chris said.
by Vernon Robertson, JEOL USA, Inc.
Photo: SEM image of polyester with lead.