Forensic epistemology: A need for research and pedagogy.

This is the third in a series of articles reporting on forensic epistemology. Our first two research articles presented scientific results that are based in experimental design; including quantitative and qualitative responses from forensic science practitioners to scenarios and evidence. Based on a synthesis of this research there is evidence of a knowledge gap in formal reasoning for some forensic practitioners, and a limited understanding of case-specific research.

Urban and Rural Spatial Delineations in Blow Fly Species (Diptera: Calliphoridae) Across Canada: Implications for Forensic Entomology.

Blow fly (Diptera: Calliphoridae) larvae are commonly used in forensic cases to determine postmortem intervals using development rates and successional changes in community composition. Studies are conducted from different regions to provide these data. We wanted to know how widely applicable these data are.

Characterizing drip patterns in bloodstain pattern analysis: An investigation of the influence of droplet impact velocity and number of droplets on static pattern features.

This work characterizes fundamental features of static drip patterns simulated for forensic bloodstain pattern analysis. The purpose of this study was to determine if and how two independent variables, impact velocity and droplet number, influence the parent stain size, shape and satellite spatter distribution of drip patterns created with whole ovine blood. To do this, 500 drip patterns were created in a controlled environment at five varying impact velocities and ten different droplet numbers on a hard paper surface.

Quantifying chemiluminescence of the forensic luminol test for ovine blood in a dilution and time series.

This study investigates the chemiluminescent reaction of whole ovine blood with a luminol solution in a time and dilution series. Replicate samples of both fresh and dried certified pathogen-free ovine blood were prepared and diluted. Seven dilution conditions from neat to 1:1000000 were created for testing.

The application of silicon sol-gel technology to forensic blood substitute development: Investigation of the spreading dynamics onto a paper surface.

This work investigates the spreading dynamics of three candidate sol-gel solutions, of ranging viscosities, surface tensions and densities, and compares them with water and two commercial blood substitute products. Droplets were created with different sizes (10 to75μL) and impact velocities (1.4 to 6.

The application of silicon sol-gel technology to forensic blood substitute development: Mimicking aspects of whole human blood rheology.

Solution-gelation chemistry has promising applications in forensic synthetic blood substitute development. This research offers a silicon-based sol-gel approach to creating stable materials that share similar rheological properties to that of whole human blood samples. Room temperature, high water content, silicon sol-gels were created using the organosilane precursors 3-glycidoxypropyltrimethoxysilane and tetraethylorthosilicate along with various concentrations of filler and pigment.

An Impact Velocity Device Design for Blood Spatter Pattern Generation with Considerations for High-Speed Video Analysis.

A mechanical device that uses gravitational and spring compression forces to create spatter patterns of known impact velocities is presented and discussed. The custom-made device uses either two or four springs (k1 = 267.8 N/m, k2 = 535.

Three physical factors that affect the crown growth of the impact mechanism and its implications for bloodstain pattern analysis.

This research uses high-speed video analysis of bloodstain impact events to investigate the influence of impact velocity, fluid depth and free-space on the characteristics of the mechanism. We focus on the changes in the crown growth over time. This work demonstrates qualitative differences in the impact mechanism under a range of impact conditions.

Affect of impact angle variations on area of origin determination in bloodstain pattern analysis.

The estimation of the location of the area of origin of a blood source is of major importance within bloodstain pattern analysis. Given this, it is particularly important to establish the accuracy of such estimations. This study examines error rates by investigation of alpha angle inaccuracies of upward directional stains and compares a virtual bloodstain pattern model to real bloodstain patterns.

A blind trial evaluation of a crime scene methodology for deducing impact velocity and droplet size from circular bloodstains.

In a previous study, mechanical engineering models were utilized to deduce impact velocity and droplet volume of circular bloodstains by measuring stain diameter and counting spines radiating from their outer edge. A blind trial study was subsequently undertaken to evaluate the accuracy of this technique, using an applied, crime scene methodology. Calculations from bloodstains produced on paper, drywall, and wood were used to derive surface-specific equations to predict 39 unknown mock crime scene bloodstains created over a range of impact velocities (2.