The effect of firearm muzzle gases on the backspatter of blood

Taylor, Michael; Laber, Terry L.; Epstein, Barton P.; Zamzow, Daniel S.; Baldwin, David P.

doi:10.1007/s00414-010-0462-4

Cited by 32 publications

(30 citation statements)

References 7 publications

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“…that had not been and will not be fired afterwards. This situation may differ from collecting samples from a 'hot' weapon, like it was done in our experiments, as there possibly is an influence of muzzle gases on droplets of backspatter [9] and thus consequently on DNA quality; however, this has not been investigated, yet.…”

Section: Discussionmentioning

confidence: 67%

Persistence of biological traces in gun barrels—an approach to an experimental model

2011

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Traces of backspatter in gun barrels after homicidal or suicidal contact shots may be a valuable source of forensic evidence. Yet, a systematic investigation of the persistence and durability of DNA from biological traces in gun barrels is lacking. Our aim was to generate a realistic model to emulate blood and tissue spatters in gun barrels generated by contact gunshots at biological targets and to analyse the persistence and typability of DNA recovered from such stains. Herein, we devise and evaluate three different models for the emulation of backspatter from contact shots: a gelatine-based model with embedded blood bags, a model based on a spongious matrix soaked with blood and covered with a thin plastic membrane and a head model consisting of an acrylic half sphere filled with ballistic gelatine and with blood bags attached to the sphere under a 3-mm silicone layer. The sampling procedure for all three models: a first shot was fired with several types of guns at each model construction and subsequently a second shot was fired at a backstop. Blood samples were collected after each shot by probing the inner surface of the front and rear end of the respective gun barrel with a sterile swab. DNA was then extracted and quantified and up to 20 different short tandem repeat (STR) systems were amplified to generate DNA profiles. Although DNA quantity and STR typing results were heterogenous between the models, all models succeeded in delivering full STR profiles even after more than one shot. We conclude that biological traces in gun barrels are robust and accessible to forensic analysis and that systematic examination of the inside of gun barrels may be advisable for forensic casework.

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Section: Discussionmentioning

confidence: 67%

Persistence of biological traces in gun barrels—an approach to an experimental model

2011

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“…The splash direction can differ from the bullet generatrix due to the flowerlike opening of hollow-point bullets at the moment of impact, the effect of the sponge (and body, in reality), the effect of muzzle gases and the bullet wake [39], etc. Therefore, the deviation angle θ ≈ 40…”

Section: Figmentioning

confidence: 99%

Prediction of blood back spatter from a gunshot in bloodstain pattern analysis

et al. 2016

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A theoretical model for predicting and interpreting blood-spatter patterns resulting from a gunshot wound is proposed. The physical process generating a backward spatter of blood is linked to the Rayleigh-Taylor instability of blood accelerated toward the surrounding air, allowing the determination of the initial distribution of drop sizes and velocities. Then the motion of many drops in air is considered with governing equations accounting for gravity and air drag. Based on these equations, a numerical solution is obtained. It predicts the atomization process, the trajectories of the back-spatter drops of blood from the wound to the ground, the impact angle, and the impact Weber number on the ground, as well as the distribution and location of bloodstains and their shape and sizes. A parametric study is undertaken to predict patterns of backward blood spatter under realistic conditions corresponding to the experiments conducted in the present work. The results of the model are compared to the experimental data on back spatter generated by a gunshot impacting a blood-impregnated sponge. A theoretical model for predicting and interpreting blood-spatter patterns resulting from a gunshot wound is proposed. The physical process generating a backward spatter of blood is linked to the Rayleigh-Taylor instability of blood accelerated toward the surrounding air, allowing the determination of the initial distribution of drop sizes and velocities. Then the motion of many drops in air is considered with governing equations accounting for gravity and air drag. Based on these equations, a numerical solution is obtained. It predicts the atomization process, the trajectories of the back-spatter drops of blood from the wound to the ground, the impact angle, and the impact Weber number on the ground, as well as the distribution and location of bloodstains and their shape and sizes. A parametric study is undertaken to predict patterns of backward blood spatter under realistic conditions corresponding to the experiments conducted in the present work. The results of the model are compared to the experimental data on back spatter generated by a gunshot impacting a blood-impregnated sponge.

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“…With the advent of digital high-speed cameras in the late 1990's, the issue of synchronization has been mitigated, and speeds up to 1 million frames per second have been made possible. For instance, strobe photography and high-speed camera visualization have been used in BPA for expirated [46] and gunshot spatters [47,48]. In the latter case, information was gathered on the complex interaction between the air flow induced by the gunshot and the flight of the cloud of sub-mm droplets.…”

Section: Physical Regimementioning

confidence: 99%

“…In the latter case, information was gathered on the complex interaction between the air flow induced by the gunshot and the flight of the cloud of sub-mm droplets. The best examples of digital high-speed videos related to BPA are the extensive studies [48,49] done by Epstein, Laber and Taylor. The related publicly available dataset [50], which is the source of Figure 6 and Figure 10, has brought attention in the BPA community to the complexity of the associated fluid dynamics phenomena.…”

Section: Physical Regimementioning

confidence: 99%

“…Area of Convergence, Directionality [13] [ 5,97] Area of Origin [13,19,68 Backspatter Pattern; Forward Spatter Pattern area of origin, weapon [48] [5, 47,110,191] Blood Clot [6,162] [ 160 , 162] Bloodstain pattern area of origin, weapon [13,35,76 [ 166,170,196] Perimeter Stain time between drip and wipe-off, [155,197,198] [ 155,188] [188] [155,163,197,198] Flow Pattern [12,162,199] [12, 162,185,199] [185] [12] Impact Pattern weapon, motion; directionality [78][79][80]128] [5] [72,128,136] Insect Stain [157,200] Mist Pattern weapon, directionality [81, 154 , 186 Spatter Stain [201] [126, [15...…”

Section: Mixingmentioning

confidence: 99%

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Fluid dynamics topics in bloodstain pattern analysis: Comparative review and research opportunities

Attinger

Moore

Donaldson

et al. 2013

Forensic Science International

151

139

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This comparative review highlights the relationships between the disciplines of bloodstain pattern analysis (BPA) in forensics and that of fluid dynamics (FD) in the physical sciences. In both the BPA and FD communities, scientists study the motion and phase change of a liquid in contact with air, or with other liquids or solids. Five aspects of BPA related to FD are discussed: the physical forces driving the motion of blood as a fluid; the generation of the drops; their flight in the air; their impact on solid or liquid surfaces; and the production of stains. For each of these topics, the relevant literature from the BPA community and from the FD community is reviewed. Comments are provided on opportunities for joint BPA and FD research, and on the development of novel FD-based tools and methods for BPA. Also, the use of dimensionless numbers is proposed to inform BPA analyses. Keywordsbloodstain pattern analysis, review, dimensionless number, drop generation, trajectory, impact, stain Disciplines Laboratory and Basic Science Research | Other Mechanical EngineeringComments NOTICE: this is the author's version of a work that was accepted for publication in Forensic Science International. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Forensic Science International, [231, 1-3, (2013) Abstract: This comparative review highlights the relationships between the disciplines of bloodstain pattern analysis (BPA) in forensics and that of fluid dynamics (FD) in the physical sciences. In both the BPA and FD communities, scientists study the motion and phase change of a liquid in contact with air, or with other liquids or solids. Five aspects of BPA related to FD are discussed: the physical forces driving the motion of blood as a fluid; the generation of the drops; their flight in the air; their impact on solid or liquid surfaces; and the production of stains. For each of these topics, the relevant literature from the BPA community and from the FD community is reviewed. Comments are provided on opportunities for joint BPA and FD research, and on the development of novel FD-based tools and methods for BPA. Also, the use of dimensionless numbers is proposed to inform BPA analyses.

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The effect of firearm muzzle gases on the backspatter of blood

Cited by 32 publications

References 7 publications

Persistence of biological traces in gun barrels—an approach to an experimental model

Persistence of biological traces in gun barrels—an approach to an experimental model

Prediction of blood back spatter from a gunshot in bloodstain pattern analysis

Fluid dynamics topics in bloodstain pattern analysis: Comparative review and research opportunities

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