It’s in the crisp coolness of the air. The leaves are changing color. Fall season is upon us. We are in the midst of autumn and the feeling of eeriness is among us as Halloween approaches.
Did you know? Our Malvern Panalytical instrumentation is being used for forensic analysis.
A range of our analytical tools and techniques are employed in the discovery of evidence or examination of materials relevant to the investigation of crimes and legal proceedings. Forensic evidence may take the form of biological samples, deposited trace materials and residues or contaminant, counterfeit or hoax materials.
Pull up a chair and settle in with your apple cider donuts and PSL (pumpkin spice latte) as we open up our vault of application uses and unearth some spine-tingling stories in materials analysis…
Spooky Skeletons and Creepy Collagen
A few years ago, we held a webinar on the application study of forensic anthropology and the analysis of post-mortem bones, featuring the ASD LabSpec® 4 Standard-Res Lab Analyzer. Our guest presenter was Dr. John Servello, a Forensic Anthropologist in the Center for Human Identification at the University of North Texas (UNT) Health Science Center (HSC) in Fort Worth, Texas.
One of the more difficult aspects of forensic anthropology is to medically and legally estimate a postmortem interval (PMI) of human skeletal remains (i.e. a determination of how long an individual has been deceased). PMI estimation becomes increasingly difficult as time of death becomes more remote, and it is therefore of immediate importance to determine whether remains are forensically significant or of non-significant origin (i.e. historical, archeological). John’s research investigated whether near-infrared (NIR) spectroscopy could be useful for reliable PMI estimation.
The technique of Near-infrared (NIR) analysis is appealing for examining cortical bone because the shorter wavelength light can penetrate the sample to greater depths than other vibrational techniques, allowing for interaction with the sample constituents. Additionally, NIR analysis requires little to no sample preparation, allows for rapid data collection, and is simple to use with minimal prior training whereas the present qualitative and quantitative tests for a determination of the PMI are time-consuming, the methods are destructive, and they require expensive, highly specialized equipment.
Also involving human skeletal remains, researchers at the University of Colorado (CU) Boulder, Christina Ryder and her advisor, Matt Sponheimer, have recently published a study and received good press for describing a method for screening bone samples to see if they contain collagen.
Collagen holds together human bones and tissue but does not age well. Long-term decomposition-related changes in bone ranging over decades to millennia (due to erosion, infiltration of soil matrix and water, the addition of soil fungi and bacteria, etc.) ultimately leads to the breakdown of collagen and the replacement of normal bone content with new mineral.
Collagen found in human remains can tell us a lot, such as how long ago a person died to what he/she may have eaten. The CU Department of Anthropology team used the ASD LabSpec 4 spectrometer to test ancient bones for the presence of collagen. The spectrometer allows for rapid collection of spectra, which can be acquired in a few seconds (“Acquisition of NIR spectra takes roughly five seconds per sample, so one could scan hundreds of samples to identify these rarities in a single afternoon.1“). The ASD NIR instrument is portable as well – about the size of a briefcase – which becomes important to this research as, “…results demonstrate that NIR spectroscopy can be used to ascertain collagen preservation status in archaeological bone from dozens of sites across the world which range in age from recent to more than 45,000 years old.1“
Read the full paper here: 1) Saving Old Bones: a non-destructive method for bone collagen prescreening
Deadly Duct tape
Sticky, flexible and resistant to tearing, people have been using duct tape as a useful item to make and fix things for decades. Duct tape has also, unfortunately, become frequently used in illicit activities.
Duct tape is generally composed of a polymeric backing, an adhesive, and fabric reinforcement (scrim) between the backing and adhesive. Duct tape backings are made in a variety of ways and observed comparison differences between tapes can serve as valuable evidence in criminal investigations.
A paper past presented at an annual meeting of the American Academy of Forensic Sciences describes how a combination of techniques, including X-ray diffraction (XRD), has been used to analyze duct tape. The study was authored by the Federal Bureau of Investigation (FBI) and involved 80+ commercially available duct tape samples. Conclusive results of the study alluded to the fact that the FBI was able to successfully indicate construction and composition variability among manufacturers.
“Samples were prepared in two ways: intact and backings only (following removal of adhesive and scrim). Each was mounted on a silicon wafer in a sample holder. Analysis was performed on a [Malvern Panalytical X-ray diffractometer]. Total analysis time was approximately 8 minutes.2“
“The technique [of XRD] has proven to be simple and reliable in the authors’ laboratory. The presence of talc in the backing was the only way two pairs of samples were discriminated using this suite of analytical techniques. XRD can distinguish between the rutile and anatase forms of titanium dioxide, and between calcite and dolomite, all of which are common duct tape pigments/fillers. Further, as demonstrated in this study, XRD can detect [phases in mineral materials]. In these ways, XRD has clearly differentiated samples where other techniques have not.2“
Read the full paper here: 2) Forensic Analysis and Discrimination of Duct Tapes
Morphologically-Directed-Raman-Spectroscopy (MDRS) combines automated particle imaging and Raman spectroscopy in one instrument, such as the Morphologi 4-ID. Particle size and shape analysis, along with chemical identification, make MDRS a reliable tool to criminalists to invaluably discriminate between multiple components for the detection of contaminant particles in a sample. The non-destructive technique provides a distinctive signature that can help identify an object or substance, determine its source or detect changes to its integrity resulting from contamination.
Particle size distributions (PSDs), for example, are commonly measured across a wide range of industries as they are important – sometimes critical – to the performance and manufacture of substances and products.
An article featured in Spectroscopy delved into how MDRS can be used to interrogate a variety of samples of forensic interest, including illicit and counterfeit drugs, hoax powders, soils, gunshot residues (GSR) and contaminants of various types.
The article concluded that, “the use of MDRS for the analysis of illicit and counterfeit drugs, soil minerals, GSR, and white powders is a novel and reliable tool that would enable criminalists to obtain more information from forensic evidence than is currently used for investigations and adjudications.”
In this video, Dr. Brooke Kammrath from the Henry C. Lee College of Criminal Justice and Forensic Sciences, University of New Haven talks about how MDRS has advanced her research into identifying hoax powders and analysis of soil samples from crime scenes:
Read the full article here: Morphologically Directed Raman Spectroscopic Analysis of Forensic Samples