Walter F. Rowe

Detection of Smokeless Powder Residue on Pipe Bombs by Micellar Electrokinetic Capillary Electrophoresis

Improvised explosive devices are an increasing concern among law enforcement agencies within the United States because of their destructive capability. Capillary electrophoresis has been used previously for the forensic analysis of inorganic constituents in explosives. Micellar electrokinetic capillary electrophoresis (MECE), also known as micellar electrokinetic chromatography (MEKC), is well suited for the forensic analysis of organic constituents of these materials because of its high sensitivity and small sample requirements. In the present study, pipe bombs filled with known types of smokeless gun powder were detonated under controlled conditions. Samples of explosive residue were collected from the post-blast fragments and analyzed using MECE. The results were compared to the known types and analyzed to investigate the feasibility of matching post-blast residue to a specific powder used as explosive charge.

Comparing the additive composition of smokeless gunpowder and its handgun-fired residues.

Detecting the use of handguns via the determination of the organic additives in smokeless gunpowder residues (OGSR) presents a promising alternative to primer metal residue analysis. Compositional analysis of the gunpowder additives nitroglycerin, diphenylamine, and ethyl centralite provides information that can associate residue samples with unfired gunpowder. We evaluated the composition of seven reloading smokeless gunpowders, both in bulk and as single particles, by ultrasonic solvent extraction/capillary electrophoresis. Handgun-fired residues obtained from three common weapon calibers loaded with the known reloading powders were compared with the unfired powders. In general, the composition of the residues was similar to that found in the unfired powders. For double-base powders, comparing the ratio of the propellant (P) to the total amount of stabilizer (S) for both residue and gunpowder samples proved to be a useful measurement for identification. This P/S ratio demonstrated that the additives in the residues did not greatly change relative to the unfired powder, providing a useful indicator to aid in forensic powder and residue evaluation.

Bullet Ricochet: A Comprehensive Review

The urban environment provides many surfaces from which bullets or shotgun pellets may ricochet. Factors that determine whether a ricochet will occur include the nature of the target surface, the angle of incidence, the shape of the projectile, and its velocity. Investigators of shooting incidents in which ricochets may have played a role must pay attention to the nature of the wounds suffered by the shooting victims, the deformation of the bullets or shotgun pellets, the presence of trace evidence on the bullets or shotgun pellets, ricochet marks on surfaces at the scene and the probable geometry of ricochet.

Errors in the estimation of the distance of fall and angles of impact blood drops

This paper presents derived equations for the estimation of the variances in the estimated distance of fall and the estimated angle of impact for blood droplets. The derived equation for the variance of the estimated distance of fall predicts that as the blood drop size approaches that of a blood droplet falling at terminal velocity, the variance of the estimate grows without limit. The derived equation for the variance in the estimated angle of impact shows that as the angle of impact approaches 90 degrees, the variance grows without limit. The validity of the equation for the estimated variance of the angle of impact was tested for five angles of impact (15, 30, 45, 60 and 75 degrees); the equation correctly predicted the observed variance up to an angle of 60 degrees.

Fungal Tunneling of Hair from a Buried Body

Tunnels produced in human head hair by fungal hyphae were examined with a light microscope and with a scanning electron microscope. The tunnels had small diameters and exhibited minimal branching. The use of a backscattered electron detector facilitated the locating of the openings of the tunnels in the surfaces of the hairs. In the backscattered electron image, tunnel openings appeared as dark spots. The tunneling hyphae did not show a preference for a particular location for entering the shaft of the hair. Some hyphae penetrated under the free edges of the cuticular scales, while others burrowed through the surfaces of the scales.

Sampling Protocols for the Detection of Smokeless Powder Residues Using Capillary Electrophoresis

Present techniques for the detection of gunshot residue rely primarily metallic primer components such as lead, barium and antimony. With the advent of reformulated primers that reduce or eliminate these elements, new methods for the detection of organic residue compounds will be needed. Micellar electrokinetic capillary electrophoresis (MECE) is one technique that has been successfully applied to the analysis of these smokeless powder residue compounds. Protocols for the recovery of the organic residue components under a variety of sampling conditions were evaluated and improved for MECE analysis. The collection of residue samples where external contaminants such as grease or blood were present on the residue substrate were investigated using both tape lifts and solvent swab protocols. In addition, residue component recovery using supercritical fluid extraction techniques was preliminarily evaluated for samples contaminated with blood.

Comparison of Methods for Estimating Range of Fire Based on the Spread of Buckshot Patterns

Three methods of measuring the spread of shotgun pellet patterns for the purpose of estimating the range of fire were applied to a series of 72 00 buckshot patterns test-fired at distances ranging from 3.6 to 10.7 m (12 to 35 ft). The methods applied were (1) the “effective shot dispersion” method of Mattoo and Nabar, (2) a method in which the area of the smallest circumscribed rectangle that will just enclose the pellet pattern is calculated, and (3) an overlay method for determining the radius of the smallest circumscribed circle that will just enclose the pellet pattern. Regression analysis was applied to the resulting measurements of the spread of the pellet patterns. The “effective shot dispersion” was found to give the best fit to a linear function and the best range-of-fire estimates. The area of the pellet patterns was found to be a quadratic function of the range of fire; this measure of pellet pattern spread was also found to have very large shot-to-shot variations. The square root of the area of the pellet pattern was found to be a linear function of the range and to give acceptable range-of-fire estimates.

The Application of Linear Regression to Range-of-Fire Estimates Based on the Spread of Shotgun Pellet Patterns

A series of shotgun pellet patterns were fired at ranges that varied from 3.9 to 15.2 m (10 to 50 ft) using a 12-gauge cylinder-bored shotgun firing No. 2 chilled shot cartridges. The spreads of the pellet patterns were measured in two ways: the radius of the smallest circle that would enclose the entire pattern was measured with a transparent overlay and the square root of the area of the smallest rectangle that would enclose the pattern was calculated. Linear regression analysis was applied to sets of data for shots at three, five, and nine ranges. For both measures of pattern spread the linear regression gave correlation coefficients greater than 0.99, indicating that a linear relationship existed between the measures of the pattern spreads and the range of fire. The confidence intervals for range-of-fire estimates at the 95% confidence level were calculated for each set of data. As expected, increasing the number of test-fired patterns decreases the confidence interval and so improves the range-of-fire estimates obtained from the test-fired patterns.

Assessment of ultra high performance supercritical fluid chromatography as a separation technique for the analysis of seized drugs: Applicability to synthetic cannabinoids.

The recent development of modern methods for ultra high performance supercritical fluid chromatography (UHPSFC) has great potential for impacting the analysis of seized drugs. In the separation of synthetic cannabinoids the technique has the potential to produce superior resolution of positional isomers and diastereomers. To demonstrate this potential we have examined the capability of UHPSFC for the analysis of two different groups of synthetic cannabinoids. The first group was a mixture of 22 controlled synthetic cannabinoids, and the second group included JWH018 and nine of its non-controlled positional isomers The clear superiority of UHPSFC over other separation techniques was demonstrated, in that it was capable of near baseline separation of all 10 positional isomers using a chiral column. In total we examined four achiral columns, including Acquity UPC(2) Torus 2-PIC, Acquity UPC(2) Torus Diol, Acquity UPC(2) Torus DEA and Acquity UPC(2) Torus 1-AA (1.7μm 3.0×100mm), and three chiral columns, including Acquity UPC(2) Trefoil AMY1, Acquity UPC(2) Trefoil CEL1 and Acquity UPC(2) Trefoil CEL2 (2.5μm 3.0×150mm), using mobile phase compositions that combined carbon dioxide with methanol, acetonitrile, ethanol or isopropanol modifier gradients. Detection was performed using simultaneous PDA UV detection and quadrupole mass spectrometry. The orthogonality of UHPSFC, GC and UHPLC for the analysis of these compounds was demonstrated using principal component analysis. Overall we feel that this new technique should prove useful in the analysis and detection of seized drug samples, and will be a useful addition to the compendium of methods for drug analysis.

Comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones

A comparison of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography for the separation of synthetic cathinones has been conducted. Nine different mixtures of bath salts were analyzed in this study. The three different chromatographic techniques were examined using a general set of controlled synthetic cathinones as well as a variety of other synthetic cathinones that exist as positional isomers. Overall 35 different synthetic cathinones were analyzed. A variety of column types and chromatographic modes were examined for developing each separation. For the ultra high performance supercritical fluid chromatography separations, analyses were performed using a series of Torus and Trefoil columns with either ammonium formate or ammonium hydroxide as additives, and methanol, ethanol or isopropanol organic solvents as modifiers. Ultra high performance liquid chromatographic separations were performed in both reversed phase and hydrophilic interaction chromatographic modes using SPP C18 and SPP HILIC columns. Gas chromatography separations were performed using an Elite-5MS capillary column. The orthogonality of ultra high performance supercritical fluid chromatography, ultra high performance liquid chromatography, and gas chromatography was examined using principal component analysis. For the best overall separation of synthetic cathinones, the use of ultra high performance supercritical fluid chromatography in combination with gas chromatography is recommended.