Targeted enrichment of whole-genome SNPs from highly burned skeletal remains.

Genetic assessment of highly incinerated and/or degraded human skeletal material is a persistent challenge in forensic DNA analysis, including identifying victims of mass disasters. Few studies have investigated the impact of thermal degradation on whole-genome single-nucleotide polymorphism (SNP) quality and quantity using next-generation sequencing (NGS). We present whole-genome SNP data obtained from the bones and teeth of 27 fire victims using two DNA extraction techniques. Extracts were converted to double-stranded DNA libraries then enriched for whole-genome SNPs using unpublished biotinylated RNA baits and sequenced on an Illumina NextSeq 550 platform. Raw reads were processed using the EAGER (Efficient Ancient Genome Reconstruction) pipeline, and the SNPs filtered and called using FreeBayes and GATK (v. 3.8). Mixed-effects modeling of the data suggest that SNP variability and preservation is predominantly determined by skeletal element and burn category, and not by extraction type. Whole-genome SNP data suggest that selecting long bones, hand and foot bones, and teeth subjected to temperatures <350°C are the most likely sources for higher genomic DNA yields. Furthermore, we observed an inverse correlation between the number of captured SNPs and the extent to which samples were burned, as well as a significant decrease in the total number of SNPs measured for samples subjected to temperatures >350°C. Our data complement previous analyses of burned human remains that compare extraction methods for downstream forensic applications and support the idea of adopting a modified Dabney extraction technique when traditional forensic methods fail to produce DNA yields sufficient for genetic identification.

Fatal footsteps: murder of undocumented border crossers in Maricopa County, Arizona.

In the past 5 years, the mortality rate among undocumented workers in Arizona has increased steadily. In 1998-1999, the number of deaths among border crossers was 28. That number increased dramatically in 1999-2000 to 106 and has exceeded 200 in each of the past 2 years. In the past, many immigrant deaths occurred as a result of dehydration and exposure (1). More recently, a new trend has emerged, that is, death of border crossers at the hands of the persons ("coyotes") hired to lead them across the border to safety. In some cases, the smugglers attempt to extort additional money from the families by holding the victims hostage once they have crossed the border into the United States. If the families fail to pay, the hostage is killed. Rival gangs are also murdering one another over their human cargo. Nine recent cases illustrate this trend in Maricopa County. In each example, the victims were bound, shot (or in one instance stabbed) and dumped in a remote desert area. All of the decedents were linked to murder for extortion by the ''coyotes'' or rival gang members.

Undocumented Border Crosser Deaths in Arizona: Expanding Intrastate Collaborative Efforts in Identification.

Undocumented Border Crosser (UBC) deaths in Arizona are a major issue faced by medicolegal authorities. Currently, the Maricopa County Office of the Medical Examiner (MCOME) is in possession of over two hundred unidentified individuals, more than half of whom are presumed to be UBCs. The primary goal of this study was to address the growing number of UBC deaths in Maricopa County in order to provide a more comprehensive picture of this important anthropological issue within the state of Arizona. Of the 107 total UBC cases evaluated for the study, the majority were male and age estimates for all individuals were between 15 to 60 years old. Modeled after the recording system established by the Pima County Office of the Medical Examiner, the biographic and geographic data for these cases were entered into a new UBC database at MCOME and later added to the online Map of Migrant Mortality.

Traumatic injury pattern analysis in a light rail transit death: a retrospective case study.

Within the context of medical examiner's offices, forensic anthropologists are increasingly being asked to assist with the interpretation of traumatic skeletal injury. This case study presents an example of trauma analysis performed by forensic anthropologists at the Maricopa County Forensic Science Center in Phoenix, Arizona. The primary goal of this study is to document an uncommon pattern of traumatic injury-severe grinding abrasions of the lower appendage that macroscopically resemble sharp force trauma, especially as observed in dismemberment cases-resulting from an individual being dragged beneath a Light Rail train for c. 1.7 miles. The abraded skeletal elements include a femoral shaft fragment, a femoral head portion, and the right foot. Second, this study aims to illustrate the efficacy of forensic anthropological analysis of patterned skeletal trauma. Finally, this study demonstrates the critical importance of analyzing scene information before drawing conclusions as to the etiology of a traumatic injury pattern.

The effects of corrosive substances on human bone, teeth, hair, nails, and soft tissue.

This research investigates the effects of household chemicals on human tissues. Five different human tissues (bone, tooth, hair, fingernails, and skin/muscle/fat) were immersed into six different corrosive agents. These agents consisted of hydrochloric acid, sulfuric acid, lye, bleach, organic septic cleaner, and Coca-Cola(®) soda. Tap water was used as a control. Tissue samples were cut to consistent sizes and submerged in the corrosive liquids. Over time, the appearance, consistency, and weight were documented. Hydrochloric acid was the most destructive agent in this study, consuming most tissues within 24 h. Sulfuric acid was the second most destructive agent in this study. Bleach, lye, and cola had no structural effects on the hard tissues of the body, but did alter the appearance or integrity of the hair, nails, or flesh in some way. The organic septic cleaner and tap water had no effect on any of the human tissue tested during the timeframe of the study.