Postmortem and Antemortem Forensic Assessment of Pediatric Fracture Healing from Radiographs and Machine Learning Classification.

A timeline of pediatric bone healing using fracture healing characteristics that can be assessed solely using radiographs would be practical for forensic casework, where the fracture event may precede death by days, months, or years. However, the dating of fractures from radiographs is difficult, imprecise, and lacks consensus, as only a few aspects of the healing process are visible on radiographs. Multiple studies in both the clinical and forensic literature have attempted to develop a usable scale to assess pediatric bone healing on radiographs using various healing characteristics. In contrast to the orthopedic definition, a fracture in forensic casework is only considered to be healed when the area around the fracture has been remodeled to the point that the fracture is difficult to detect on a radiograph or on the surface of the bone itself, a process that can take several years. We subjectively assessed visible characteristics of healing in radiograms of fractures occurring in 942 living children and adolescents. By dividing these assessments into learning and test (validation) sets, the accuracy of a newly proposed fracture healing scale was compared to a previous study. Two machine learning models were used to test predictions of the new scale. All three models produced similar estimates with substantial imprecision. Results corroborate the Malone model with an independent dataset and support the efficacy of using less complex models to estimate fracture age in children.

Blast Suppression Foam, Aqueous Gel Blocks, and their Effect on Subsequent Analysis of Forensic Evidence.

In addition to having blast mitigation properties, aqueous foam concentrate AFC-380 blast suppression foam is designed to capture aerosolized chemical, biological, and radioactive particles during render-safe procedures of explosive devices. Exposure to aqueous environments and surfactants may negatively affect forensic evidence found at the scene, but the effects of AFC-380 foam and aqueous gel on the preservation and subsequent analysis of forensic evidence have not previously been investigated. Sebaceous finger and palm prints and DNA samples on paper, cardboard, tape, and various metal and plastic items, along with hairs, carpet and yarn fibers, and inks and documents, were exposed to AFC-380 foam. Similar mock evidence was also exposed to a superabsorbent gel of the type found in aqueous gel blocks used for shrapnel containment. Exposure to foam or aqueous gel was associated with a dilution effect for recovered DNA samples, but quality of the samples was not substantially affected. In contrast, exposure to AFC-380 foam or gel was detrimental to development of latent finger and palm prints on any substrate. Neither the hair nor the fiber samples were affected by exposure to either the foam or gel. Indented writing on the document samples was detrimentally affected by foam or gel exposure, but not inks and toners. The results from this study indicate that most types of forensic evidence recovered after being exposed to aqueous gel or blast suppression foam can be reliably analyzed, but latent finger and palm prints may be adversely affected.

Depiction of ethnic facial aging by forensic artists and preliminary assessment of the applicability of facial averages.

Many characteristics of facial aging are common to all. The age of their onset and which characteristics tend to predominate varies among individuals depending on many factors including their genetic makeup, life experiences, environment in which they live, and the regional, ethnic, or socially perceived group to which they belong. Forensic artists are often asked to provide sketches, 2D or 3D digital renderings, or sculptures representative of how an individual may appear at an older age based on a provided photograph, victim or witness description, and/or cranial remains. The challenge escalates when the subject is a member of a regional, ethnic, or other socially perceived group to which the artist has had little or no exposure. We describe aspects of adult facial aging that are of particular relevance to the forensic artist, applicable software tools, and pertinent facial databases, especially those emphasizing non-white populations. We demonstrate that facial averaging offers two key advantages to the artistic portrayal of facial aging: first, the technique requires relatively small reference databases from groups that may present logistical challenges to collect and second, that a facial average provides a useful representation of the gestalt of the age and ethnicity cohort to which a subject belongs. The artist may use an average along with other available information such as photo reference books, eyewitness descriptions, photos of immediate family members, and cranial structure to guide production of a facial composite drawing, digital age progression, or sculpture of the subject in question.

Stature estimation using measurements of the cranium for populations in the United States.

Stature estimation is an important component of the biological profile. Human crania are sometimes recovered in the absence of other skeletal material in forensic casework, and stature estimation equations using cranial measurements have not been developed for populations in the United States. Both simple and multiple regression equations for estimating stature were developed from standard cranial measurements taken from both a cranial CT dataset and the Forensic Data Bank, and the resulting equations were tested using a separate dataset. A weak to moderate correlation with stature was found for some of the measurements tested. Tests of the sex- and ancestry-specific equations and pooled sex equations produced accurate estimated stature ranges for most of the individuals in the test dataset, but large 95% confidence intervals (±14-16cm) for these equations can produce only an imprecise estimated stature range for an unidentified individual. Pooled ancestry equations also produced accurate estimated stature ranges for many of the individuals in the test dataset, but with even larger 95% confidence intervals (±18-20cm). The results of this study indicate that stature can be estimated using cranial measurements, but the resulting 95% confidence intervals produce stature ranges that are too broad to use in most forensic casework.

Application of Enhanced Point Estimators to a Sample of In Vivo CT-derived Facial Soft Tissue Thicknesses.

Facial approximations based on facial soft tissue depth measurement tables often utilize the arithmetic mean as a central tendency estimator. Stephan et al. (J Forensic Sci 2013;58:1439) suggest that the shorth and 75-shormax statistics are better suited to describe the central tendency of non-normal soft tissue depth data, while also accommodating normal distributions. The shorth, 75-shormax, arithmetic mean, and other central tendency estimators were evaluated using a CT-derived facial soft tissue depth dataset. Differences between arithmetic mean and shorth mean for the tissue depths examined ranged from 0 mm to +2.3 mm (average 0.6 mm). Differences between the arithmetic mean plus one standard deviation (to approximate the same data points covered by the 75-shormax) and 75-shormax values ranged from -0.8 mm to +0.7 mm (average 0.2 mm). The results of this research suggest that few practical differences exist across the central tendency point estimators for the evaluated soft tissue depth dataset.