Portable high‐resolution automated 3D imaging for footwear and tire impression capture

The forensic science community raised the need for improved evidence recognition, collection, and visualization analytical instrumentation for field and laboratory use. While the 3D optical techniques for imaging static objects have been extensively studied, there is still a major gap between current knowledge and collecting high‐quality footwear and tire impression evidence. Among optical means for 3D imaging, digital fringe projection (DFP) techniques reconstruct 3D shape from phase information, achieving camera‐pixel spatial resolution. This paper presents a high‐resolution 3D imaging technology using DFP techniques dedicated to footwear and tire impression capture. We developed fully automated software algorithms and a graphical user interface (GUI) that allow anyone without training to operate for high‐quality 3D data capture. We performed accuracy evaluations and comparisons comparing with the commercial high‐end 3D scanner and carried out qualitative tests for various impressions comparing with the current practices. Overall, our technology achieves similar levels of accuracy and resolution with a high‐end commercially available 3D scanner, while having the merits of being (1) more affordable; (2) much easier to operate; and (3) more robust. Compared with the current practice of casting, our technology demonstrates its superiority because it (1) is non‐destructive; (2) collects more evidence detail than casts, especially when an impression is fragile; (3) requires less time and money to collect each piece of evidence; and (4) results in a digital file that can easily be shared with other examiners.     

Ecological Validity of the Inventory of Problems-29 (IOP-29): an Italian Study of Court-Ordered,Psychological Injury Evaluations Using the Structured Inventory of Malingered Symptomatology (SIMS) as Criterion Variable

The Inventory of Problems-29 (IOP-29; Viglione, Giromini, & Landis, Journal of Personality Assessment, 99(5), 534–544, 2017) is a 29-item, recently published, self-administered test aimed at assessing the credibility of various symptom presentations. Although available research strongly supports the use of this symptom validity test in malingering-related contexts, to date, only few studies have analyzed data from real-life forensic evaluations. To fill this gap and explore ecological and convergent validity, the current study analyzed data from 74 court-ordered evaluations aimed at establishing the possible presence of psychological injury. Such evaluations are high-stakes situations in which exaggeration or malingering occur relatively often. We used a research-supported and popular symptom validity test, i.e., the Structured Inventory of Malingered Symptomatology (SIMS; Smith & Burger, Journal of the American Academy on Psychiatry and Law, 25:180–183, 1997), as our criterion variable. The IOP-29 produced excellent area under the curve (AUC) values of .98 with a recommended SIMS total score cutoff (≥ 17) and .99 when eliminating too-close-to-classify cases (Rogers & Bender, 2018) and very large Cohen’s d effect sizes of 2.98 and 3.59, respectively. Crucially, when implementing established cut scores from previous research, the IOP-29 yielded very high specificity and sensitivity rates, and the predictions from the two tests were strikingly similar. Taken together, these findings support the strong convergent validity of the IOP-29 and its utility in applied clinical and forensic settings.     

STR analysis of artificially degraded DNA-results of a collaborative European exercise

Degradation of human DNA extracted from forensic stains is, in most cases, the result of a natural process due to the exposure of the stain samples to the environment. Experiences with degraded DNA from casework samples show that every sample may exhibit different properties in this respect, and that it is difficult to systematically assess the performance of routinely used typing systems for the analysis of degraded DNA samples. Using a batch of artificially degraded DNA with an average fragment size of approx. 200 bp a collaborative exercise was carried out among 38 forensic laboratories from 17 European countries. The results were assessed according to correct allele detection, peak height and balance as well as the occurrence of artefacts. A number of common problems were identified based on these results such as strong peak imbalance in heterozygous genotypes for the larger short tandem repeat (STR) fragments after increased PCR cycle numbers, artefact signals and allelic drop-out. Based on the observations, strategies are discussed to overcome these problems. The strategies include careful balancing of the amount of template DNA and the PCR cycle numbers, the reaction volume and the amount of Taq polymerase. Furthermore, a careful evaluation of the results of the fragment analysis and of automated allele calling is necessary to identify the correct alleles and avoid artefacts.     

Three-dimensional surface topography acquisition and analysis for firearm identification

In the last decade, computer-based systems for the comparison of microscopic firearms evidence have been the subject of considerable research work because of their expected capability of supporting the firearms examiner through the automated analysis of large amounts of evidence. The Integrated Ballistics Identification System, which is based on a two-dimensional representation of the specimen surface, has been widely adopted in forensic laboratories worldwide. More recently, some attempts to develop systems based on three-dimensional (3D) representations of the specimen surface have been made, both in the literature and as industrial products, such as BulletTRAX-3D, but fundamental limitations in achieving fully automated identification remain. This work analyzes the advantages and disadvantages of a 3D-based approach by proposing an approach and a prototype system for firearms evidence comparison that is based on the acquisition and analysis of the 3D surface topography of specimens, with particular reference to cartridge cases. The concept of 3D virtual comparison microscope is introduced, whose purpose is not to provide fully automated identification, but to show how the availability of 3D shape information can provide a whole new set of verification means, some of them being described and discussed in this work, specifically, visual enhancement tools and quantitative measurement of shape properties, for supporting, not replacing, the firearm examiner in reaching the final decision.     

A forensic entomology case from the Amazon rain forest of Brazil

The first case of application of forensic entomology in the Brazilian Amazonia is described. The corpses of 26 men were found in the rainforest in Rondonia State, Brazil. Fly larvae collected on the bodies during autopsy were identified as Paralucilia fulvinota (Diptera, Calliphoridae). No data or specimens were collected at the crime scene. At the laboratory, the larvae developed into pupae in 58 h and into adults in 110.5 h. The total development time for P. fulvinota was measured in field experiments inside the forest. The age of the larvae when collected from the bodies was estimated as the difference between the time required for them to become adults and the total development time for this species. The estimated age of the maggots and the minimum postmortem interval was 5.7 days.     

Rapid in situ repeatable analysis of drugs in powder form using reflectance near-infrared spectroscopy and multivariate calibration

This study takes the first step toward in situ analysis of powder drugs which does not require any alteration of the samples. A fast, inexpensive analytical method based on reflectance near-infrared (NIR) spectrometry and multivariate calibration was applied. A diode-array fiber-optic portable spectrometer in the 900-1700 nm range was employed. Samples were laboratory-prepared ternary powders (diacetylmorphine, caffeine, and paracetamol). Partial least squares regression was applied. The choice of the standard samples for calibration and validation was performed through a D-optimal experimental design. The explained variance was higher than 90%, and the relative root mean square errors were <2%. The number of principal components (6) was very low when compared with the number of raw variables (356 absorbance values). Response plots showed slopes and intercepts were very close to optimal values. Correlation coefficients ranged between 0.909 and 0.989. The method here proposed proved to be competitive with Fourier transform NIR spectrometry.     

Experimental results on data analysis algorithms for extracting and interpreting edge feature data for duct tape and textile physical fit examinations

A physical fit is an important observation that can result from the forensic analysis of trace evidence as it conveys a high degree of association between two items. However, physical fit examinations can be time-consuming, and potential bias from analysts may affect judgment. To overcome these shortcomings, a data analysis algorithm using mutual information and a decision tree has been developed to support practitioners in interpreting the evidence. We created these tools using data obtained from physical fit examinations of duct tape and textiles analyzed in previous studies, along with the reasoning behind the analysts' decisions. The relative feature importance is described by material type, enhancing the knowledge base in this field. Compared with the human analysis, the algorithms provided accuracies above 90%, with an improved rate of true positives for most duct tape subsets. Conversely, false positives were observed in high-quality scissor cut (HQ-HT-S) duct tape and textiles. As such, it is advised to use these algorithms in tandem with human analysis. Furthermore, the study evaluated the accuracy of physical fits when only partial sample lengths are available. The results of this investigation indicated that acceptable accuracies for correctly identifying true fits and non-fits occurred when at least 35% of a sample length was present. However, lower accuracies were observed for samples prone to stretching or distortion. Therefore, the models described here can provide a valuable supplementary tool but should not be the sole means of evaluating samples.     

Do bone elasticity and postmortem interval affect forensic fractographic analyses?

Forensic fractographic features of bone reliably establish crack propagation in perimortem injuries. We investigated if similar fracture surface features characterize postmortem fractures. Experimentally induced peri- and postmortem fractures were used to assess if fractographic features vary as bone elasticity decreases during the postmortem interval (PMI). Thirty-seven unembalmed, defleshed human femoral shafts from males and females aged 33–81 years were fractured at varying PMIs with a drop test frame using a three-point bending setup and recorded with a high-speed camera. Vital statistics, cause of death, PMI length, temperature, humidity, collagen percentage, water loss, fracture energy, and fractography scores were recorded for each sample. Results showed that fractographic features associated with perimortem fractures were expressed in PMIs up to 40,600 accumulated degree hours (ADH), or 60 warm weather days. Hackle was the most consistently expressed feature, occurring in all fractures regardless of ADH. The most variable characteristics were wake features (78.4%) and arrest ridges (70.3%). Collagen percentage did not correlate strongly with ADH (r = −0.04, p = 0.81); however, there was a strong significant correlation between ADH and water loss (r = 0.74, p < 0.001). Multinomial logistic regression showed no association between fractographic feature expression and ADH or collagen percentage. In conclusion, forensic fractographic features reliably determine initiation and directionality of crack propagation in experimentally induced PMIs up to 40,600 ADH, demonstrating the utility of this method into the recent postmortem interval. This expression of reliable fractographic features throughout the early PMI intimates these characteristics may not be useful standalone features for discerning peri- versus postmortem fractures.     

Italian population data on two new short tandem repeat loci: D2S1338 and Penta E

A population study on two new short tandem repeat (STR) loci D2S1338 (a tetranucleotide repeat) and Penta E (a pentanucleotide repeat) was performed on 208 unrelated Italian Caucasians. The DNA was amplified by polymerase chain reaction (PCR) and separation and detection of the amplified STR fragments were carried out by use of a PE/ABD PRISM 377 DNA Sequencer 377 automated system (Applied Biosystems Division/Perkin-Elmer). Both loci meet Hardy-Weinberg expectations. There is no evidence for departures from expectations between the two loci. The combined Probability of Discrimination and Probability of Exclusion for the two STR loci are 0.999155 and 0.944925, respectively. The results demonstrate that these two regions can be useful for differentiating among individuals, particularly in concert with other STR loci.     

Potency levels of regulated cannabis products in Michigan 2021–2022

Evaluation of cannabinoid concentrations in products from the legal cannabis market has been fraught with uncertainty. The lack of standardized testing methodology and the susceptibility of cannabinoids to degradation under certain storage conditions complicates the efforts to assess total tetrahydrocannabinol (THC) levels across wide geographic areas. There are few peer-reviewed surveys of cannabinoid concentrations in regulated products. Those that have been done have not characterized the effects of differences in analytical methodology, sample population, and storage conditions. Viridis Laboratories, which operates two cannabis safety compliance facilities in Michigan, has analyzed over 34,000 cannabis products throughout 2021 and 2022 before the sale in the regulated market. Fifteen cannabinoids in cannabis flower, concentrates, and infused products were tested using methanolic extraction and analysis by high-performance liquid chromatography with diode-array detection. Methods were validated before use, and the flower analysis procedure was certified by the Association of Analytical Collaboration. All the samples were tested before submission for sale and therefore had not undergone prolonged storage. The results are compared with those seen in other states as well as in the illicit market. Total THC levels in cannabis flower from the regulated market are significantly higher than those seen in illicit products. The distribution of cannabinoid levels is similar in flowers intended for either the medicinal or adult-use markets, with an average potency of 18%–23% of total THC. Total THC in concentrates averages up to 82%. Other cannabinoids are observed at significant levels, mostly in products specifically formulated to contain them. These results may act as a benchmark for potency levels in the regulated market.