Forensic Sciences 2020

The forensic investigation of crime involves answering four basic questions: who, what, where, and when.  Tools exist to answer questions of who, what and where, but the question when is often important in criminal investigations and is the one question for which tools don’t exist to produce an answer. If a suspect or victim of a crime frequents the scene of a crime because they reside there, it might be expected that their DNA could be found.  If it were possible however to establish that the age of a stain found in the house coincided with the time a crime was committed, the value of the stain for the investigation is strengthened.  It is also often impossible to estimate the time of death for a victim of homicide whose skeletal remains are found in a clandestine grave. For the past several years we have been working on developing a method to estimate the age of body fluid stains through the use of molecular methods.  The approach we have taken is to use the extent of degradation of a collection of messenger RNA (mRNA) molecules present in blood or semen stains.  We have shown that RNA degradation is predictable and can be used to create standard degradation curves that enables the age of an unknown stain to be estimated with high accuracy.  In more recent studies, the effect of environmental conditions have been investigated on the rate of RNA degradation.  Both heat and relative humidity accelerate degradation, and current efforts are aimed at incorporating changes in the degradation rate constant due to environmental conditions into an algorithm for estimating sample age. Early studies are also underway to explore rhythmic changes in gene expression during the daily cycling of males and females of varying age.  The goal of these studies is to explore the possibility of determining the time of day biological evidence was created at a crime scene.

Learning Objectives:

1. Be able to describe the nature of RNA degradation in dried blood stains

2. Understand the environmental effects of heat, relative humidity, and substrate, on the rate of RNA degradation in a dried blood stain

3. Understand the relationship between gene expression during the circadian rhythm and estimating the time of day a blood stain was created

Crime scene investigation is more than just processing or documentation of crime scenes, nor is it just the collection or packaging of physical evidence. It is the first step and the most crucial step of any forensic investigation. The foundation of all forensic investigations is based on the ability of the crime scene investigator or forensic scientist to recognize the potential pattern evidence, large or small, visible or latent, exculpatory or exculpatory, at the crime scene. The subsequent examination and identification of the pattern evidence along with determination of the possible source or origin of the evidence, that is, its individualization, are the next steps in the forensic investigation process. Proper crime scene investigation is the starting point for the process of establishing what has happened, when and where happed, who is involved and why and how it occurred. Of course, careful processing, documentation, and collection of pattern evidence are integral parts of the ‘investigation process’ and crime scene reconstruction. If the potential pattern evidence was not recognized, or collected, or properly reconstructed, the forensic value of this piece evidence is lost.  Despite available current forensic technologies, specialized equipment and personnel, the integrity of forensic services system and the effectiveness utilization of physical evidence in crime solving are only as good as the integrity of the crime scene investigator and the objective legal system that supports those functions. Routine and new crime scene pattern reconstruction concepts, and cases will be used to demonstrate the newest methods and techniques used in crime scene reconstruction.

Learning Objectives:

1. What is pattern evidence and where to find it at crime scene

2. There are several steps in the process of classification and reconstruction of pattern evidence

3. The process moves from pattern recognition, comparison, identification of class characteristics toward reconstruction

4. The methods of pattern evidence comparison and pattern reconstruction

5. The value and limitation of pattern evidence reconstruction

The toxicology of particulate matter is complicated by characteristics not normally encountered when addressing poisonings associated with chemical substances.  Particle shape, surface reactivity, electrical properties, hydration and solubility characteristics all play critical roles at the biological interface.  Compounding the toxicologist’s difficulties are wide variations in these characteristics in the environment as well as the dynamic pathophysiological response of the host.  My talk will review the important role of the immune system’s cellular response in the lung following inhalation of elongate mineral particles.  The presentation will address modern and historical controversies associated with the presence of toxic elongate minerals in the environment, cosmetics and other consumer products.  A forensic case history involving the characterization of elongate minerals that ravaged a small Montana town will be used to describe the complexities of characterization and ongoing controversies of this challenging forensic problem.

Learning Objectives:

1. What are the similarities and differences between elongate mineral particles and asbestos?

2. What is “frustrated phagocytosis” in mineral particle induced lung disease?

3. Name 4 types of lung disease induced by elongate mineral partices

4. What is “activity-based” exposure monitoring?

The necrobiome is the community of organisms that use or are affected by decomposing organic matter.  Decomposing organic matter comes in the form of dead plant matter (biomass) or that of dead animals, including humans.  Using research into how these communities (e.g., insects, pollen, microbes) colonize, use and change during the decomposition of vertebrate carcasses can inform science with potential forensic utility. One emerging area of forensic research has been into postmortem microbiomes and how they have potential to estimate postmortem intervals, postmortem submersion intervals, manner/cause of death and other areas of investigative interest. While recent research on postmortem microbiomes shows excellent promise, there are several challenges that will limit practical use during death investigations; these issues span from basic experimental desing and context to understanding the extent of variability in postmortem microbiomes across human demographics, ethics, geography and time.  This presentation provides an introduction to the necrobiome commonly associated with decomposing animals, including humans; a summary of past and current research into postmortem microbiome science; example case studies; and a discussion of the challenges that will require consideration and solutions before postmortem microbiome evidence becomes acceptable and used within the forensic sciences.

Learning Objectives

1. Define the postmortem microbiome and two examples of how it can be potentially used in forensic sciences.
2. Identify various challenges in using the postmortem microbiome in forensics.
3. Describe the pros and cons of performing research in anthropological research facilities versus autopsies (or cases) to provide postmortem microbiome data that can be used in future routine death investigation.

The ever-increasing number of deaths along the U.S.-México border and the diversification in the demographic characteristics of the Latin American migrants, who perish in this region, demand new approaches to forensic anthropological casework. Current rates of positive identification must be improved so that the unknown forensic case can be re-associated with the once living person, the individual’s remains returned to the family, and the needs of social justice can be served. Studies using genetic and skeletal data alike have revealed differences in ancestry for many of the spatially-defined groups that are distributed across Latin America. Demographic research on migration networks for México have found distinctive transit pathways El Norte, whereby migrants of different origins are associated with particular destinations across the U.S.-México border. In this presentation, I will argue for the value of extending these two lines of research on the living to the identification of the dead for methodological improvement in the forensic context. Specifically, I will show how, when combined, information on geographic variation in ancestry composition and spatial trends in migration are critical to building statistical models optimized for the probabilistic determination of personal identity for migrant fatalities recovered along our southern border. By quantifying these biogeographic patterns in terms of the unknown individual’s relative estimates of continental-level ancestry, geographic location of origin, and place of death along the border, I will demonstrate that it is possible to predict the individual’s sending region. Through this discussion, I will illustrate how geospatial and machine learning methods can be used to improve traditional forensic procedures by directing case investigation, providing probable locations for finding next of kin, and reducing the pool of potential matches from missing persons lists. In conclusion, I will advocate for adopting a bio-cultural approach to identification that leverages multi-disciplinary methods to aid in this human rights work.

Learning Objectives:

1. Introduce the concept of biogeography and explain its value as an alternative biological profile parameter to single-group ancestry

2. Demonstrate how novel geospatial and machine learning methods can be used to infer place of origin for unknown remains

3. Explain how trihybrid ancestry estimates can be generated from skeletal data using admixture algorithms comparable to those employed in forensic genetics

The potential for cognitive bias in forensic evidence interpretation and crime scene investigation continues to receive attention and debate within forensic and academic communities. Starting with just a few studies in the early 2000s, cognitive bias has now been examined in nearly every forensic discipline and is a dedicated topic within many scientific committees and working groups around the world. This presentation will track the progression of cognitive bias studies and their influence on forensic science practice, as well as highlighting the challenges inherent in designing and carrying out such research. We will also examine the benefits to implementing contextual information management, and how rethinking the role of contextual information in forensic decision-making facilitates some much-needed discussion about the true nature of scientific reasoning in forensic science.

This will be an interactive presentation. Please bring a pen and paper and play along as we challenge some of our own biases!

Learning Objectives:

1. Identify the challenges inherent in cognitive bias research as it relates to forensic evidence interpretation

2. Understand the difference between “bias” and the “application of task-relevant contextual information.”

3. Recognize the value of contextual information management procedures, regardless of the outcome of cognitive bias studies.

Microhaplotypes (microhaps) are biomarkers less than 300 nucleotides long that display multiple allelic combinations. The main advantages of microhaps over conventional short tandem repeats (STRs) include the absence of stutter, same-size alleles within each locus, lower mutation rate, and ancestry informative alleles. These forensically relevant loci can yield a power of discrimination similar to STRs while enhancing human identification (HID), mixture deconvolution and biogeographic ancestry prediction. Sanger sequencing does not allow determining the cis/trans relationship among closely related SNPs while massively parallel sequencing (MPS) allows determining the parental haplotypes at each locus by clonally sequencing of each DNA molecule if they are included in the same amplicon. Currently, STR panels are used for mixture deconvolution and SNP assays are used for ancestry inference. Microhaplotypes can be used for both functions allowing, for example, to infer the ancestry of a minor contributor to a mixture (DNA intelligence). In this presentation we discuss the current status of the research conducted in the GW-FMB lab on this new multi-function DNA marker and its potential impact to the field of in forensic genetics.

Learning Objectives:

1. Molecular basis of microhaplotypes

2. Informativeness and power of discrimination of microhaplotypes

3. Mixture deconvolution via microhaplotypes

Hydroxychloroquine and chloroquine are long-standing antimalarial drugs recently brought into the spotlight as potential treatments for the pandemic-causing coronavirus (SARS-CoV-2). Notable publicity of their effectiveness in preliminary clinical trials seems to have contributed to increased calls to US poison control centers, and one recent report of accidental fatal ingestion of chloroquine phosphate algaecide. It is important for forensic toxicologists to be aware of the adverse effects and potential drug interactions associated with these drugs, which are widely available as treatments for Systemic Lupus Erythematosus (SLE) and aquarium cleaning products, respectively. Analytical testing for hydroxychloroquine and chloroquine may be accomplished using gas chromatography/mass spectrometry (GC/MS), liquid chromatography/tandem mass spectrometry (LC-MS/MS) and other methodologies (e.g., LC / time-of-flight) in blood and other body fluids. These compounds are not typically included in general unknown screens, so knowledge of the signs and symptoms may be important for informing testing strategies. Reference ranges for therapeutic and toxic effects can be used for comparison with concentrations of the parent compounds. Reports of overdose from the literature have described cardiac arrhythmias, hypotension, electrolyte imbalances, and coma.

Learning Objectives:

1. Attendees will learn to recognize the signs, symptoms and other indicators from case history that hydroxychloroquine or chloroquine may be relevant to a forensic toxicology investigation

2. Attendees will identify other drugs and medical conditions that may interact with hydroxychloroquine and chloroquine to produce toxic effects

3. Attendees will become familiar with recommended practices for collection, storage and analysis of forensic toxicology samples for hydroxychloroquine and chloroquine

In late 2019, nearly a decade into a life sentence, Lydell Grant was released from a Texas prison after being convicted of a murder that he did not commit. The victim, Aaron Scheerhorn, was stabbed multiple times in a parking lot outside of a bar in Houston. A DNA mixture was recovered from the victim’s fingernails but was too complex to analyze at the time of the original trial. Mr. Grant’s conviction resulted primarily based on the testimony of six eyewitnesses, all of whom identified him as the killer. During the trial and the entirety of his imprisonment, Grant vehemently denied his involvement in the crime. In 2018, forensic DNA expert Dr. Angie Ambers and a legal team from the Innocence Project of Texas requested access to evidentiary samples collected from the victim during autopsy. Mixed DNA data generated from the victim’s fingernails was sent for analysis using a “probabilistic genotyping” software program called TrueAllele®. Analysis of the raw data from this DNA mixture not only excluded Mr. Grant as the source of the foreign DNA, but resulted in a CODIS database hit that identified the actual murderer of Mr. Scheerhorn. This presentation will provide an overview of Grant’s case, as well as a discussion of subjectivity issues with previous DNA mixture interpretation approaches and the improved (more  objective) analytical capabilities provided by probabilistic genotyping software programs.

Learning Objectives:

1. Identify issues regarding DNA mixture interpretation

2. Learn about current probabilistic genotyping programs for forensic casework

3. Understand how probabilistic genotyping can assist with post-conviction DNA testing

The current standard methodology in forensic DNA typing relies on amplification of short tandem repeat (STR) markers by the polymerase chain reaction (PCR) and allele sizes (i.e., length-based) determined for each locus using capillary electrophoresis (CE). Massively parallel sequencing (MPS), also known as next generation sequencing (NGS), allows high throughput sequencing of STR amplicons, which can identify nominal length-based (LB) genetic variation but equally as well inter-allelic sequence (sequence-based; SB) variation. The increased effective number of alleles per marker for some STR loci improves discrimination power, which may be invaluable in some cases of kinship analysis and for mixture de- convolution. Furthermore, allelic variation captured using MPS may be useful towards understanding of STR mutations and their rates and may contribute to evolutionary studies using STR markers. One issue with current massively parallel sequencing (MPS) is the need to capture flanking region sequence variation to exploit the full power of forensically relevant STR loci. The application of such data will increase our knowledge and understanding of each locus, gain additional genetic information about population specific genetic parameters, increase the power of discrimination of a locus, and potentially aid in mixture de-convolution efforts. The underlying genetic variation needs to be described through studies on various population groups.

Learning Objectives:

1. Understand the advances in sequence-based technologies in Forensic DNA typing

2. Understand the major commonalities and differences between current and futuristic DNA typing methods

3. Acknowledge the complexities of the human genome for forensic human identity applications