Evidence analysis and processing

Analyzing, comparing, and evaluating forensic digital images relies on understanding two essential elements: image quality and image clarity.  Resolution provides image quality, while bit depth provides clarity between the details in an image. It is important to understand how image quality and clarity can affect the probative value of a forensic digital image as well as an examiner’s ability to accurately analyze those images. 

This webinar was presented by the NIJ Forensic Technology Center of Excellence on August 3, 2021.
 

Over the last ten years, numerous novel psychoactive substances (NPS) have emerged in the recreational drug supply. Upon synthesis or discovery, each of these drugs has been given a name other than its IUPAC chemical name, primarily for ease of communication. This has resulted in various naming convention for NPS, sometimes multiple within a given subclass. This webinar is aimed at tackling the naming conventions for NPS and the associated challenges encountered along the way.

Microhaplotypes (microhaps) are biomarkers fewer than 300 nucleotides long that display multiple allelic combinations. The main advantages of microhaps over conventional short tandem repeats (STRs) include the 1) absence of stutter, 2) same-size alleles within each locus, 3) lower mutation rate, and 4) 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.

LatentSleuth is a novel software tool set designed for (and with direct feedback from) latent print examiners. The toolset includes a small-scale automated fingerprint identification system (AFIS) matcher that leverages a novel matching algorithm that calculates a warp between a latent print image and a given reference print image. This webinar will demonstrate a comprehensive quantification of a latent images entire structure and how that quantification is exploited in a commercially available workstation for latent print examination. 

In the sixth and final webinar, participants will be introduced to the use of PMCT in the investigation of a variety of unnatural deaths not discussed in previous webinars.  Topics include overdose deaths, select asphyxial mechanisms of death, and sharp force injury.

This webinar was presented by the NIJ Forensic Technology Center of Excellence on May 18, 2021. 

In the fifth webinar, participants will be introduced to the use of PMCT in the investigation of natural deaths.  At the New Mexico OMI, a PMCT scan may be used to rule out trauma in apparently natural deaths, or to confirm a natural cause of death.  Depending on investigative details (circumstances, age, and medical history), and the PMCT findings, pathologists may choose to perform an external exam or a full autopsy.

This webinar was presented by the NIJ Forensic Technology Center of Excellence on May 11, 2021.

In the third webinar, participants will be introduced to the use of PMCT for examining decedents with gunshot wounds, both homicidal and self-inflicted.  At the New Mexico OMI, a PMCT scan is performed in virtually all gunshot wound (GSW) related deaths.  In cases of suspected homicide or suspicious suicides, autopsy is also performed.  However, in non-suspicious cases involving self-inflicted GSW, PMCT is combined with an external examination, and sometimes a partial autopsy to retrieve a retained projectile, replacing the full autopsy. 

This webinar will introduce participants to the use of PMCT in the diagnosis of blunt force trauma.  PMCT scan may be used to diagnose fatal trauma in certain situations, allowing an external examination with postmortem CT to supplant an autopsy, which may better honor religious and cultural requests of grieving family members.  Non-suspicious, traumatic deaths, such as motor vehicle collisions, are such an example.  Additionally, PMCT often provides additional documentation of internal injuries where fatal injuries are obvious on external examination. 

In the first webinar, participants will be introduced to x-ray computed tomography (CT) and some key differences between CT and traditional x-ray.  The basic specifications of a CT scanner (such as bore diameter, maximum image size, and table specifications) will be introduced, with reference to their impact on whole body post-mortem scanning in particular.  Basic considerations for deploying a CT scanner in a medical examiner setting (cost, personnel, space, safety) will also be discussed.  

In the second webinar of the Post-mortem Computed Tomography Series, participants will be introduced to the use of PMCT as a triage tool in a busy forensic pathology practice.  Participants will first learn about the history of the use of PMCT at the New Mexico Office of the Medical Investigator (OMI) and the existing research and literature on the efficacy of PMCT in the medical examiner setting. 

This webinar was presented by the NIJ Forensic Technology Center of Excellence on April 20, 2021. 

This webinar will evaluate the submitted responses for bloodstain pattern analysis proficiency tests over the past several years with the purpose of gaining insight into trends within the science.  The focus will be on erroneous conclusions and how an evaluation of the most problematic patterns can assist in moving the discipline forward.

This webinar was presented by the NIJ Forensic Technology Center of Excellence on April 15, 2021.

Touch DNA is a potentially powerful sample type for forensic casework, but is challenging to work with due to low quantity, variable deposition amounts, and fundamental questions regarding stability over time. In this webinar we describe best-practices and initial results related to comprehensive studies of the stability of touch DNA after exposure to different environmental conditions.

This webinar was presented by the NIJ Forensic Technology Center of Excellence on March 11, 2021.

The webinar will cover microbial research in nontraditional forensics such as environmental contamination, foodborne illness, plant pathogens, and antibiotic resistance source tracking. The webinar will conclude with needs that must be met for chains of custody and current limitations to forensic microbiology.

This webinar was hosted by the NIJ Forensic Technology Center of Excellence on June 21, 2021.

The NIJ Forensic Technology Center of Excellence hosted a panel of subject matter experts to discuss emerging methods for body fluid analysis. This webinar is in three sections: 1) Proteomics and its potential in high-throughput forensic laboratories. 2) Surface Enhanced Raman Spectroscopy and the rapid detection and identification of body fluids. 3) MicroRNA, mRNA, and the development of a microfluidic device used to detect and differentiate body fluids from an unknown sample.

Throughout the Probabilistic Genotyping of Evidentiary DNA Typing Results virtual workshop series, we have reviewed aspects of DNA mixture interpretation and have seen that probabilistic genotyping (PG) software can serve as a tool to assist the DNA Examiner in identifying possible genotype sets within a mixture and then calculating a likelihood ratio (LR). Approaches to modeling were shared by the developers of different PG software programs, followed by examples of internal validation studies and results.

Has a person of interest contributed DNA to a mixture obtained from evidence? Is that DNA associated with a crime? Both are questions that cannot be answered with absolute certainty. This module of the Probabilistic Genotyping of Evidentiary DNA Typing Results workshop series addresses the uncertainty and limitations of probabilistic genotyping systems that are used to calculate likelihood ratios and infer genotype sets from DNA typing results.

Biological modeling, statistical theory, and the computer processing of probabilistic genotyping systems are based on long- standing principles, yet their usage in U.S. courts has been limited to the past few years. This module of the Probabilistic Genotyping of Evidentiary DNA Typing Results web series addresses topics relevant to the admissibility of probabilistic genotyping results and the presentation of results in criminal proceedings. Various decisions related to probabilistic genotyping will be summarized from a legal perspective.