Calcium and Phosphorus Detection Using Benchtop Versus Handheld X‐ray Fluorescence Spectrometers

Elemental analysis of calcium (Ca) and phosphorus (P) has been shown to be useful in differentiating skeletal and nonskeletal material. X‐ray fluorescence spectrometry (XRF) is an attractive, nondestructive technique for forensic anthropologists, and the development of portable XRF instrumentation is promising for field applications. This study examines the performance of handheld XRF instrumentation operated in air compared to a traditional benchtop XRF device that has the ability to control the analysis atmosphere. Both instruments can be used to effectively distinguish skeletal from nonskeletal remains. However, as the measurement atmosphere affects detection levels for calcium and phosphorus, Ca/P ratios obtained from the instruments and analysis conditions were found to differ significantly, with analyses conducted in air showing significantly lower phosphorus detection. Consequently, comparison of Ca/P ratios to conclude skeletal versus nonskeletal origin must be based on data collected under similar analysis conditions.     

Forensic Comparison of Automotive Aluminum Wheel Fragments Using Synchrotron Radiation X‐ray Fluorescence with 18‐ and 116‐keV Excitation X‐rays

The performance of synchrotron radiation X‐ray fluorescence (SR‐XRF) spectrometry for nondestructive discrimination of small fragments of automotive aluminum wheels was studied. Fragments (< 500 × 500 μm²) of 45 kinds of wheels were first analyzed by scanning electron microscopy–energy dispersive spectroscopy (SEM‐EDS) and then by SR‐XRF. Despite the Mg/Al intensity ratio being a useful identification index, SEM‐EDS was not efficient enough because of the absence of other meaningful indicators of comparison. Conversely, pairwise comparison was conducted and a 92.9% identification was achieved via SR‐XRF using 18‐keV X‐rays. Trace heavy elements in the high‐energy region were detected by SR‐XRF using 116‐keV X‐rays, and an 82.9% identification was obtained. Combined use of 18‐ and 116‐keV X‐rays allowed 98.2% identification. Hence, SR‐XRF is a powerful tool for nondestructive discrimination of automotive aluminum wheels with high precision using trace elements in a wide energy region.     

Multimethod Resolution of a Small‐Scale Case of Commingling

This study highlights the use of multiple methods for resolving a case of commingled human remains. Skeletal remains were located in a marijuana field in rural northern California by law enforcement. Although initially buried in shallow graves, the remains of two decedents were disturbed by large carnivores and scattered over a wide area. The remains were submitted by law enforcement for forensic anthropological analysis and resolution of commingling. To segregate the remains of the two individuals, a number of methods were employed, including: (i) physical matching of fragmented remains; (ii) articulation to evaluate joint congruence; (iii) visual pair‐matching of bilateral elements; (iv) osteometric pair‐matching; (v) evaluation of taphonomic patterns; (vi) DNA analysis; and (vii) portable X‐ray spectrometry (pXRF). This multimethod approach resulted in accurate resolution of the commingling and facilitated reconstruction of the biological profiles, taphonomic patterns, and trauma analysis for each individual.     

X‐ray Powder Diffraction for Characterization of Raw Materials in Banknotes

We report about the X‐ray powder diffraction characterization of crystalline materials used to produce genuine and counterfeit banknotes, performed with a single‐crystal diffractometer that permits fast and nondestructive measurements in different 0.5‐mm sized areas; 20‐euro denomination genuine banknotes were analyzed, and results were compared with counterfeit banknotes. The analysis shows that the papers used to print real banknotes are composed, as expected, of cotton‐based cellulose and titanium dioxide as crystalline additive, but different polymorphs of TiO₂ for different emission countries are evidenced. The counterfeit banknotes are composed of cellulose based on wood pulp; moreover, an unexpected significant quantity of TiO₂ was found to be mixed with calcite, indicating that the paper employed by forgers is not simply a common low‐cost type. The crystalline index and intensity ratios between the peaks attributable to cellulose and fillers can provide additional information to trace back paper suppliers for forensic purposes.     

Elemental Analysis of Variably Contaminated Cremains Using X‐ray Fluorescence Spectrometry

Analyzing and identifying skeletal remains becomes increasingly difficult when remains have been cremated, especially in cases where the cremated material may have been intentionally contaminated with nonskeletal material. This study examined the potential of X‐ray fluorescence spectrometry (XRF) to detect the presence of nonskeletal contaminants in samples of cremains. Eleven samples of cremains were variably combined with concrete mix and analyzed using XRF. Photon counts of elements in each sample were analyzed, and the coefficient of determination (R²) using unweighted linear regression as a function of percent cremains was calculated. Results showed that with changes in the proportion of skeletal material and contaminant, there were significant (R² > 0.90) changes in detected levels of phosphorus, potassium, zinc, aluminum, and sulfur. The use of XRF is concluded to be a valid approach in the identification of the presence of nonskeletal material in potentially contaminated cremains.     

The Survival of Gunshot Residues in Cremated Bone: An Inductively Coupled Plasma Optical Emission Spectrometry Study

Gunshot residue (GSR) has been sought and demonstrated on many types of material and with many techniques. Inductively coupled plasma optical emission spectrometry (ICP‐OES) could be a useful method on difficult substrates, but a systematic study on burnt material has never been performed. Hence, this study aims at evaluating the usefulness and reliability of this method on burnt samples. Sixteen adult bovine ribs (eight with soft tissues, eight totally skeletonized) were shot using two kinds of projectile (both 9 mm full metal‐jacketed or unjacketed). Then, every sample was led to complete calcination in an electric oven. The area of the gunshot entrance wound was swabbed and analyzed by ICP‐OES; the results were also correlated with a previously published parallel study by scanning electron microscopy (SEM) equipped with an SEM–energy dispersive X‐ray analyzer. ICP‐OES proved to be very sensitive and reliable even on degraded material and can be an appropriate nondestructive method for detecting residues on difficult and delicate substrates such as burnt bone.     

Using Paint to Investigate Fires: An ATR‐IR Study of the Degradation of Paint Samples Upon Heating

Fire investigation is a challenging area for the forensic investigator. The aim of this work was to use spectral changes to paint samples to estimate the temperatures to which a paint has been heated. Five paint samples (one clay paint, two car paints, one metallic paint, and one matt emulsion) have been fully characterized by a combination of attenuated total reflectance Fourier transform infrared (ATR‐IR), Raman, X‐ray fluorescence spectroscopy and powder X‐ray diffraction. The thermal decomposition of these paints has been investigated by means of ATR‐IR and thermal gravimetric analysis. Clear temperature markers are observed in the ATR‐IR spectra namely: loss of ν(C = O) band, >300°C; appearance of water bands on cooling, >500°C; alterations to ν(Si–O) bands due to dehydration of silicate clays, >700°C; diminution of ν(CO₃) and δ(CO₃) modes of CaCO₃, >950°C. We suggest the possible use of portable ATR‐IR for nondestructive, in situ analysis of paints.     

Assessment of the Effects Exerted by Acid and Alkaline Solutions on Bone: Is Chemistry the Answer?

The treatment of corpses with extremely acid or basic liquids is sometimes performed in criminal contexts. A thorough characterization by chemical analysis may provide further help to macroscopic and microscopic analysis; 63 porcine bone samples were treated with solutions at different pH (1–14) for immersion periods up to 70 days, as well as in extremely acidic sulfuric acid solutions (9 M/18 M) and extremely basic sodium hydroxide. Inductively coupled optical emission spectrometry (ICP‐OES)/plasma mass spectrometry (ICP‐MS), Fourier transform infrared spectroscopy (FT‐IR), energy dispersive X‐ray analysis (EDX), X‐ray powder diffraction (XRPD), and scanning electron microscopy (SEM) showed that only the sulfuric acid solution 18 M was able to completely dissolve the sample. In addition, chemical analysis allowed to recognize the contact between bone and substances. Hydrated calcium sulfate arose from extreme pH. The possibility of detecting the presence of human material within the residual solution was demonstrated, especially with FT‐IR, ICP‐OES, and EDX.     

Development of Latent Fingermarks on Various Surfaces Using ZnO‐SiO2 Nanopowder

Fingermarks are one of the most useful forms of evidence in identification and can provide generalized proof of identity in crime investigation. They are developed using various conventional powders. The novel nanopowder ZnO‐SiO₂ was synthesized via the conventional heating method and characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy‐dispersive X‐ray (EDX) analysis, transmission electron microscope (TEM), and X‐ray diffraction (XRD). The mean particle size of ZnO‐SiO₂ nanopowder calculated through TEM was 32.9 nm. The development of fingermarks was carried out by powder dusting and small particle reagent (SPR) methods. Powder dusting method was used for the development of latent fingermarks on various dry, nonporous, and semi‐porous surfaces. The SPR method was also applied to wet nonporous surface. The developed latent fingermarks using ZnO‐SiO₂ nanopowder were found to have excellent quality with very clear third‐level ridges detail and had better visibility than commercially available white powder.     

Infrared Spectra of U.S. Automobile Original Finishes (1998–2000). IX. Identification of Bismuth Oxychloride and Silver/White Mica Pearlescent Pigments Using Extended Range FT‐IR Spectroscopy,XRF Spectrometry,and SEM/EDS Analysis

Bismuth oxychloride (BiOCl) was the first viable synthetic pearl pigment developed 50 years ago. It was only used for a limited time period in automotive paint (model years 1998–2000), serving to produce luster for a single Chrysler black metallic color. Identification of this pigment in an unknown automotive paint can thus facilitate determination of the vehicle of origin. Bismuth oxychloride imparts effects similar to those produced by silver/white mica pearlescent pigments, and such a pigment was used together with bismuth oxychloride in at least one original equipment manufacturer (OEM) basecoat. Silver/white micas are now used primarily in white pearl tricoat systems. This article describes the identification of bismuth oxychloride and silver/white mica pearlescent pigments in automotive finishes using FT‐IR spectroscopy, X‐ray fluorescence (XRF) spectrometry, and SEM/EDS analysis. Data for some cadmium pigments, which were used in automotive paint several decades ago, are also presented as they produce infrared absorptions similar to that of bismuth oxychloride.     

Trace Elemental Analysis of Titanium Dioxide Pigments and Automotive White Paint Fragments for Forensic Examination Using High‐Energy Synchrotron Radiation X‐Ray Fluorescence Spectrometry*

Abstract: High‐energy synchrotron radiation x‐ray fluorescence spectrometry (SR‐XRF) utilizing 116 keV x‐rays was used to characterize titanium dioxide pigments (rutile) and automotive white paint fragments for forensic examination. The technique allowed analysis of K lines of 9 trace elements in 18 titanium dioxide pigments (rutile), and 10 trace elements in finish coat layers of seven automotive white paint fragments. High‐field strength elements (HFSE) were found to strongly reflect the origin of the titanium dioxide (TiO₂) pigments, and could be used as effective parameters for discrimination and classification of the pigments and paint fragments. A pairwise comparison of the finish coat layers of seven automotive white paint fragments was performed. The trace elements in the finish coat layers detected by the high‐energy SR‐XRF were especially effective for identification. By introducing the trace element information of primer and electrocoat layers, all the automotive white paint fragments could be discriminated by this technique.     

Testing a Novel 3D Printed Radiographic Imaging Device for Use in Forensic Odontology

There are specific challenges related to forensic dental radiology and difficulties in aligning X‐ray equipment to teeth of interest. Researchers used 3D printing to create a new device, the combined holding and aiming device (CHAD), to address the positioning limitations of current dental X‐ray devices. Participants (N = 24) used the CHAD, soft dental wax, and a modified external aiming device (MEAD) to determine device preference, radiographer's efficiency, and technique errors. Each participant exposed six X‐rays per device for a total of 432 X‐rays scored. A significant difference was found at the 0.05 level between the three devices (p = 0.0015), with the MEAD having the least amount of total errors and soft dental wax taking the least amount of time. Total errors were highest when participants used soft dental wax—both the MEAD and the CHAD performed best overall. Further research in forensic dental radiology and use of holding devices is needed.     

Validation of X-ray fluorescence spectrometry for determining osseous or dental origin of unknown material

Forensic anthropological examinations typically involve the analysis of human skeletal remains, but in cases where samples are very small and/or physically compromised, it may first be necessary to determine whether the material is even osseous or dental in origin. X-ray fluorescence spectrometry (XRF) is a technique that reveals the elemental composition of materials and is hypothesized to have utility in such cases. XRF analysis was conducted on a variety of tissues and materials in unaltered and altered (damaged) states. With few exceptions, osseous and dental tissues in unaltered and altered conditions contained characteristic levels of calcium and phosphorus, while other materials did not. Materials could be accurately identified as osseous or dental in origin based on the calcium and phosphorus levels identified by XRF, and we therefore conclude that XRF analysis is a valid and effective means of determining osseous or dental origin of unknown material.     

Lead Theft—A Study of the “Uniqueness” of Lead from Church Roofs

In the United Kingdom, theft of lead is common, particularly from churches and other public buildings with lead roofs. To assess the potential to distinguish lead from different sources, 41 samples of lead from 24 church roofs in Northamptonshire, U.K, have been analyzed for relative abundance of trace elements and isotopes of lead using X‐ray fluorescence (XRF) and inductively coupled plasma mass spectrometry, respectively. XRF revealed the overall presence of 12 trace elements with the four most abundant, calcium, phosphorus, silicon, and sulfur, showing a large weight percentage standard error of the mean of all samples suggesting variation in the weight percentage of these elements between different church roofs. Multiple samples from the same roofs, but different lead sheets, showed much lower weight percentage standard errors of the mean suggesting similar trace element concentrations. Lead isotope ratios were similar for all samples. Factors likely to affect the occurrence of these trace elements are discussed.     

X‐ray Scattering Evaluation of Ultrastructural Changes in Human Dental Tissues with Thermal Treatment

Micro‐ and ultrastructural analysis of burned skeletal remains is crucial for obtaining a reliable estimation of cremation temperature. Earlier studies mainly focused on heat‐induced changes in bone tissue, while this study extends this research to human dental tissues using a novel quantitative analytical approach. Twelve tooth sections were burned at 400–900°C (30‐min exposure, increments of 100°C). Subsequent combined small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) experiments were performed at the Diamond Light Source synchrotron facility, where 28 scattering patterns were collected within each tooth section. In comparison with the control sample, an increase in mean crystal thickness was found in burned dentine (2.8‐fold) and enamel (1.4‐fold), however at a smaller rate than reported earlier for bone tissue (5–10.7‐fold). The results provide a structural reference for traditional X‐ray scattering methods and emphasize the need to investigate bone and dental tissues separately to obtain a reliable estimation of cremation temperature.     

Gunshot residues on dry bone after decomposition-a pilot study

Abstract: Very little literature exists concerning radiochemical and microscopic analyses of gunshot wounds in decomposed material, and even less concerning skeletonized samples; the most advanced technologies may provide useful indications for the diagnosis of suspect lesions, especially if gunshot wounds are no longer recognizable. However, we know very little of the survival of gunshot residues (GSR) in skeletonized samples. This study examined nine gunshot wounds produced on pig heads which then underwent skeletonization for 4 years, and four gunshot entries on human heads from judicial cases which were then macerated to the bone in water; the samples underwent scanning electron microscopy coupled with energy dispersive X‐ray (SEM‐EDX) analysis. Positive results for GSR were observed only in four of the nine animal samples and in all four human samples. Among the human samples, two lesions showed Pb and Sb, one lesion only Pb, and one Pb, Sb, and Ba. This pilot study showed the survival of GSR in skeletal material and therefore the crucial importance of SEM‐EDX analyses on skeletonized material. Further studies are needed in order to ascertain the role of environmental modifications of GSR.     

X‐ray Diffraction and Rietveld Refinement in Deferrified Clays for Forensic Science

Soil vestiges might provide information about a crime scene. The Rietveld method with X‐ray diffraction data (RM‐XRD) is a nondestructive technique that makes it possible to characterize minerals present in the soils. Soil clays from the metropolitan region of Curitiba (Brazil) were submitted to DCB treatment and analyzed using XRD with CuK_α radiation in the step‐scan mode (0.02° 2θ/5 s). The GSAS+EXPGUI software was used for RM refinement. The RM‐XRD results, together with the principal component analysis (PCA) (52.6% total variance), showed the kaolinite predominance in most analyzed samples and the highest quartz contents in “site 1.” Higher anatase, and gibbsite and muscovite contents influenced discrimination, mainly in “site 3” and “site 1,” respectively. These results were enough to discriminate clays of four sites and two horizons using a reduced amount of sample showing that the technique can be applied to the investigation into soil vestiges.     

Identification through X-ray fluorescence analysis of dental restorative resin materials: a comprehensive study of noncremated, cremated, and processed-cremated individuals

Tooth-colored restorative materials are increasingly being placed in the practice of modern dentistry, replacing traditional materials such as amalgam. Many restorative resins have distinct elemental compositions that allow identification of brand. Not only are resins classifiable by elemental content, but they also survive extreme conditions such as cremation. This is of significance to the forensic odontologist because resin uniqueness adds another level of certainty in victim identification, especially when traditional means are exhausted. In this three-part study, unique combinations of resins were placed in six human cadavers (total 70 restorations). Simulated ante-mortem dental records were created. In a blind experiment, a portable X-ray fluorescence (XRF) unit was used to locate and identify the resin brands placed in the dentition. The technique was successful in location and brand identification of 53 of the restorations, which was sufficient to enable positive victim identification among the study group. This part of the experiment demonstrated the utility of portable XRF in detection and analysis of restorative materials for victim identification in field or morgue settings. Identification of individuals after cremation is a more difficult task, as the dentition is altered by shrinkage and fragmentation, and may not be comparable with a dental chart. Identification of processed cremains is a much greater challenge, as comminution obliterates all structural relationships. Under both circumstances, it is the nonbiological artifacts that aid in identification. Restorative resin fillings can survive these conditions, and can still be named by brand utilizing elemental analysis. In a continuation of the study, the cadavers were cremated in a cremation retort under standard mortuary conditions. XRF was again used to analyze retrieved resins and to identify the individuals based on restorative materials known to exist from dental records. The cremains were then processed and the analysis was repeated to determine whether restorative resins could be found under this extreme condition. Under both circumstances, sufficient surviving resin material was found to distinguish positively each individual in the study group. This study showed the utility of XRF as an analytical tool for forensic odontology and also the significance of the role of restorative resins in victim identification, even after cremation.     

Refreshing the Aged Latent Fingerprints with Ionizing Radiation Prior to the Cyanoacrylate Fuming Procedure: A Preliminary Study

One of the crucial factors determining the cyanoacrylate deposit quality over latent fingerprints appeared to be the extent of the humidity. This work focuses on the enhancement/refreshment of age‐degraded latent fingerprints by irradiating the samples with UV, X‐ray, or thermal neutrons prior to the cyanoacrylate (CA) fuming. Age degradation of latent fingerprints deposited on glass surfaces was examined through the decrease in the number of characteristic minutiae counts over time. A term “critical day” was introduced for the time at which the average number of identifiable minutiae definitions drops to one‐half. Fingerprints older than their “critical day” were exposed to either UV, X‐ray, or thermal neutrons. Identical reference samples were kept unexposed. All samples, both reference and irradiated, were developed during a single CA fuming procedure. Comparative latent fingerprint analysis showed that exposure to ionizing radiation enhances the CA fuming, yielding a 20‐30% increase in average minutiae count.     

Understanding Variations of Soil Mapping Units and Associated Data for Forensic Science

Soil samples have potential to be useful in forensic investigations, but their utility may be limited due to the inherent variability of soil properties, the wide array of analytical methods, and complexity of data analysis. This study examined the differentiation of similar soils based on both gross (texture, color, mineralogy) and explicit soil properties (elemental composition, cation exchange, Fe‐oxyhydroxides). Soils were collected from Fallbrook and adjacent map units from Riverside and San Diego Counties in California. Samples were characterized using multiple techniques, including chemical extracts, X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy. Results were analyzed using multiple analytical approaches to compare counties and land uses. Some analyses (XRD, extractions) were better at distinguishing among samples than others (color, texture). Ratios of rare earth elements were particularly useful for distinguishing samples between counties. This potential to “fingerprint” soils illustrates the usefulness of a comprehensive soil database for criminal investigators.