Pub Date : 2020-10-01DOI: 10.1080/10401334.2020.1838147
G. J. Davis
A confession: I wanted to like this text more than I did. I first encountered this book in its second edition while training in forensic pathology in the 80 s, and it was formative in my understand...
{"title":"Spitz and fisher’s medicolegal investigation of death: Guidelines for the application of pathology to crime investigation, 5th ed","authors":"G. J. Davis","doi":"10.1080/10401334.2020.1838147","DOIUrl":"https://doi.org/10.1080/10401334.2020.1838147","url":null,"abstract":"A confession: I wanted to like this text more than I did. I first encountered this book in its second edition while training in forensic pathology in the 80 s, and it was formative in my understand...","PeriodicalId":44383,"journal":{"name":"Canadian Society of Forensic Science Journal","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/10401334.2020.1838147","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47627804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-01DOI: 10.1080/00085030.2020.1834755
Della A. Wilkinson, S. Holowachuk, C. Corbett, K. Antonation, Lisa Rostek, A. Wotherspoon, K. Toole, Nathan B. Unsworth, J. Coumbaros, V. Rastogi, Brad Donais, Jackie Osmond, C. Baxter
Abstract Chemical, biological, radiological, nuclear and explosive (CBRNE) response teams are responsible for mitigating and investigating events such as the distribution of anthrax letters throughout the US Postal Service in 2001. One consideration will be the examination of contaminated physical evidence to identify those responsible. Decontamination agents are often used to inactivate or neutralize chemical and/or biological warfare agents so that once-contaminated objects can be handled safely. The objective of this project was to determine the impact of different decontamination agents on physical evidence including DNA, documents, fingermark and footwear evidence. In Phase 1, vaporous hydrogen peroxide (VHP), gamma irradiation, dry fogging, chlorine dioxide, MODEC MDF-500, Bioxy-S, ozone and formaldehyde were tested. Promising decontamination agents were selected for Phase 2 when physical evidence was exposed to Bacillus thuringiensis (Bt), an anthrax surrogate, prior to decontamination. VHP, gamma irradiation, dry fogging, formaldehyde and chlorine dioxide were tested in Phase 2. Results indicate that several forensic analyses were impacted. VHP and gamma irradiation were used across different laboratories with inconsistent results observed for some forensic protocols. Further investigation indicated that these results could be explained by variation in contamination protocols between laboratories. Les équipes d'intervention chimique, biologique, radiologique, nucléaire et explosive (CBRNE) sont chargées d'atténuer et d'enquêter sur des événements tels que la distribution de lettres d'anthrax dans l'ensemble du service postal américain en 2001. Une considération sera l'examen des preuves physiques contaminées pour identifier les responsables. Les agents de décontamination sont souvent utilisés pour inactiver ou neutraliser les agents de guerre chimiques et/ou biologiques afin que des objets autrefois contaminés puissent être manipulés en toute sécurité. L'objectif de ce projet était de déterminer l'impact de différents agents de décontamination sur les preuves physiques, y compris l'ADN, les documents, les traces de doigt et les chaussures. En phase 1, le peroxyde d'hydrogène vaporeux (VHP), l'irradiation gamma, la brumisation sèche, le dioxyde de chlore, le MODEC MDF-500, le Bioxy-S, l'ozone et le formaldéhyde ont été testés. Des agents de décontamination prometteurs ont été sélectionnés pour la phase 2 lorsque des preuves physiques ont été exposées à Bacillus thuringiensis (Bt), un substitut de l'anthrax, avant la décontamination. Le VHP, l'irradiation gamma, la brumisation sèche, le formaldéhyde et le dioxyde de chlore ont été testés à la phase 2. Les résultats indiquent que plusieurs analyses médico-légales ont été touchées. VHP et l'irradiation gamma ont été utilisée dans différents laboratoires avec des résultats incohérents observés pour certains protocoles médico-légaux. Une enquête plus approfondie a indiqué que ces résultats pour
{"title":"Effect of decontamination agents following biological contamination on fingermarks, footwear, documents and DNA","authors":"Della A. Wilkinson, S. Holowachuk, C. Corbett, K. Antonation, Lisa Rostek, A. Wotherspoon, K. Toole, Nathan B. Unsworth, J. Coumbaros, V. Rastogi, Brad Donais, Jackie Osmond, C. Baxter","doi":"10.1080/00085030.2020.1834755","DOIUrl":"https://doi.org/10.1080/00085030.2020.1834755","url":null,"abstract":"Abstract Chemical, biological, radiological, nuclear and explosive (CBRNE) response teams are responsible for mitigating and investigating events such as the distribution of anthrax letters throughout the US Postal Service in 2001. One consideration will be the examination of contaminated physical evidence to identify those responsible. Decontamination agents are often used to inactivate or neutralize chemical and/or biological warfare agents so that once-contaminated objects can be handled safely. The objective of this project was to determine the impact of different decontamination agents on physical evidence including DNA, documents, fingermark and footwear evidence. In Phase 1, vaporous hydrogen peroxide (VHP), gamma irradiation, dry fogging, chlorine dioxide, MODEC MDF-500, Bioxy-S, ozone and formaldehyde were tested. Promising decontamination agents were selected for Phase 2 when physical evidence was exposed to Bacillus thuringiensis (Bt), an anthrax surrogate, prior to decontamination. VHP, gamma irradiation, dry fogging, formaldehyde and chlorine dioxide were tested in Phase 2. Results indicate that several forensic analyses were impacted. VHP and gamma irradiation were used across different laboratories with inconsistent results observed for some forensic protocols. Further investigation indicated that these results could be explained by variation in contamination protocols between laboratories. Les équipes d'intervention chimique, biologique, radiologique, nucléaire et explosive (CBRNE) sont chargées d'atténuer et d'enquêter sur des événements tels que la distribution de lettres d'anthrax dans l'ensemble du service postal américain en 2001. Une considération sera l'examen des preuves physiques contaminées pour identifier les responsables. Les agents de décontamination sont souvent utilisés pour inactiver ou neutraliser les agents de guerre chimiques et/ou biologiques afin que des objets autrefois contaminés puissent être manipulés en toute sécurité. L'objectif de ce projet était de déterminer l'impact de différents agents de décontamination sur les preuves physiques, y compris l'ADN, les documents, les traces de doigt et les chaussures. En phase 1, le peroxyde d'hydrogène vaporeux (VHP), l'irradiation gamma, la brumisation sèche, le dioxyde de chlore, le MODEC MDF-500, le Bioxy-S, l'ozone et le formaldéhyde ont été testés. Des agents de décontamination prometteurs ont été sélectionnés pour la phase 2 lorsque des preuves physiques ont été exposées à Bacillus thuringiensis (Bt), un substitut de l'anthrax, avant la décontamination. Le VHP, l'irradiation gamma, la brumisation sèche, le formaldéhyde et le dioxyde de chlore ont été testés à la phase 2. Les résultats indiquent que plusieurs analyses médico-légales ont été touchées. VHP et l'irradiation gamma ont été utilisée dans différents laboratoires avec des résultats incohérents observés pour certains protocoles médico-légaux. Une enquête plus approfondie a indiqué que ces résultats pour","PeriodicalId":44383,"journal":{"name":"Canadian Society of Forensic Science Journal","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/00085030.2020.1834755","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44921287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-08-11DOI: 10.1080/00085030.2020.1799658
N. Nagachar, T. Tiedge, A. Lakhtakia, M. N. McCormick, R. Roy
Abstract A systematic study was undertaken on the influence of environmental insult on the efficacy of developing a latent fingermark on a nonporous substrate by the deposition of a conformal nanoscale columnar thin film (CTF) on it. Four warm-weather and one cold-weather environmental conditions were chosen as representative for Pennsylvania. Three durations of environmental insult were selected: a day, seven days, and 30 days. Fingermarks were collected from one male donor and one female donor on five different types of substrates. The evaporant material for the deposition of a CTF on a specific fingermark sample was specifically chosen based on a prior study. Photographs of every fingermark were graded for quality after collection, after enduring the chosen environmental insult for a particular duration, and after CTF development. The results of the study on 750 fingermark samples indicate that environmental insult does not always degrade and can even improve the quality of fingermarks, and CTF deposition thereafter may considerably enhance the insulted fingermarks for visualization.
{"title":"Development of environmentally insulted fingermarks on nonporous forensically relevant substrates with conformal columnar thin films","authors":"N. Nagachar, T. Tiedge, A. Lakhtakia, M. N. McCormick, R. Roy","doi":"10.1080/00085030.2020.1799658","DOIUrl":"https://doi.org/10.1080/00085030.2020.1799658","url":null,"abstract":"Abstract A systematic study was undertaken on the influence of environmental insult on the efficacy of developing a latent fingermark on a nonporous substrate by the deposition of a conformal nanoscale columnar thin film (CTF) on it. Four warm-weather and one cold-weather environmental conditions were chosen as representative for Pennsylvania. Three durations of environmental insult were selected: a day, seven days, and 30 days. Fingermarks were collected from one male donor and one female donor on five different types of substrates. The evaporant material for the deposition of a CTF on a specific fingermark sample was specifically chosen based on a prior study. Photographs of every fingermark were graded for quality after collection, after enduring the chosen environmental insult for a particular duration, and after CTF development. The results of the study on 750 fingermark samples indicate that environmental insult does not always degrade and can even improve the quality of fingermarks, and CTF deposition thereafter may considerably enhance the insulted fingermarks for visualization.","PeriodicalId":44383,"journal":{"name":"Canadian Society of Forensic Science Journal","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2020-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/00085030.2020.1799658","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49343730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-02DOI: 10.1080/00085030.2020.1803030
A. Braga, W. Knaap, R. Summerbell
Abstract The purpose of this study was to examine growth rates for the filamentous fungus Scopulariopsis brevicaulis on decomposing porcine remains in relation to three controlled temperatures. This study was performed by inoculating porcine tissue samples retrieved from the same source. These samples were placed into three controlled environments to examine changes over a month. This study was intended to develop a photographic and quantifiable chronology of fungal growth that can be used as a reference by investigative personnel interested in utilizing mycological evidence in death investigations. Providing this novel information to the inadequately studied discipline of forensic mycology is intended to help establish the credibility of this field. These efforts will aid in interpreting post-mortem intervals for cadavers experiencing fungal growth in controlled indoor environments.
{"title":"Examining growth rates of Scopulariopsis brevicaulis on decomposing porcine remains","authors":"A. Braga, W. Knaap, R. Summerbell","doi":"10.1080/00085030.2020.1803030","DOIUrl":"https://doi.org/10.1080/00085030.2020.1803030","url":null,"abstract":"Abstract The purpose of this study was to examine growth rates for the filamentous fungus Scopulariopsis brevicaulis on decomposing porcine remains in relation to three controlled temperatures. This study was performed by inoculating porcine tissue samples retrieved from the same source. These samples were placed into three controlled environments to examine changes over a month. This study was intended to develop a photographic and quantifiable chronology of fungal growth that can be used as a reference by investigative personnel interested in utilizing mycological evidence in death investigations. Providing this novel information to the inadequately studied discipline of forensic mycology is intended to help establish the credibility of this field. These efforts will aid in interpreting post-mortem intervals for cadavers experiencing fungal growth in controlled indoor environments.","PeriodicalId":44383,"journal":{"name":"Canadian Society of Forensic Science Journal","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2020-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/00085030.2020.1803030","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45168665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-31DOI: 10.1080/00085030.2020.1756117
Trevor I. Stamper, L. Pharr, G. Anderson, Carleen Gondor, Alex C Dedmon, R. Kimsey
Abstract We describe how an unusual facultative scavenger, the black-billed magpie (Pica hudsonia (Sabine)), took advantage of the compromised nature of burnt skin to scavenge porcine remains with extensive, and hitherto unreported, efficiency. Scavenging appears to be minimally reported for this species. We serendipitously made these observations while conducting a workshop on forensic entomology in Missoula, Montana, in 2015. We also illustrate how excluding larger vertebrate scavengers may reveal and highlight the taphonomic effects of smaller facultative scavengers not so excluded. Such observations could be important to forensic investigators in wildlife or homicide investigations of burnt remains.
{"title":"First observation of burnt vertebrate carrion scavenging by black-billed magpies (Pica hudsonia (Sabine)) highlights the need to evaluate all possible scavengers at a site","authors":"Trevor I. Stamper, L. Pharr, G. Anderson, Carleen Gondor, Alex C Dedmon, R. Kimsey","doi":"10.1080/00085030.2020.1756117","DOIUrl":"https://doi.org/10.1080/00085030.2020.1756117","url":null,"abstract":"Abstract We describe how an unusual facultative scavenger, the black-billed magpie (Pica hudsonia (Sabine)), took advantage of the compromised nature of burnt skin to scavenge porcine remains with extensive, and hitherto unreported, efficiency. Scavenging appears to be minimally reported for this species. We serendipitously made these observations while conducting a workshop on forensic entomology in Missoula, Montana, in 2015. We also illustrate how excluding larger vertebrate scavengers may reveal and highlight the taphonomic effects of smaller facultative scavengers not so excluded. Such observations could be important to forensic investigators in wildlife or homicide investigations of burnt remains.","PeriodicalId":44383,"journal":{"name":"Canadian Society of Forensic Science Journal","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2020-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/00085030.2020.1756117","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46996736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-25DOI: 10.1080/00085030.2020.1767855
Lilian Skokan, Catherine Daigle, A. Tremblay, Cyril Muehlethaler
Abstract In Canada, the knife is amongst the stabbing weapons most frequently used in the commission of violent crimes, particularly homicides. Although under-exploited, the search for fibres resulting from contact between a textile material and a receiver surface can provide relevant information on the activity at their origin. Although cotton-polyester blended textiles are among the most commonly produced worldwide, no research seems to focus on studying the proportions of fibres transferred to the knife blade during such an attack which constitutes an important lack of information for practitioners in the field. This study involved the construction of a stabbing simulation device that performed perforations under controlled parameters (e.g. force, speed and orientation of perforation) with the use of two kitchen knives with straight and serrated blades. Simulations were conducted on a set of four blended textiles to further investigate the transfer of cotton and polyester fibres and the correlation to donor textile characteristics. The transfer mainly lies on the properties of the fibres. Since cotton fibres are shorter, less resistant and less elastic than polyester fibres, they are favoured during transfer and can be found in greater proportion. Finally, the study provides some guidelines, including the addition of a scraping step, for the recovery of fibres from knife blades.
{"title":"Le transfert différentiel des fibres de coton et de polyester lors d’agressions au couteau","authors":"Lilian Skokan, Catherine Daigle, A. Tremblay, Cyril Muehlethaler","doi":"10.1080/00085030.2020.1767855","DOIUrl":"https://doi.org/10.1080/00085030.2020.1767855","url":null,"abstract":"Abstract In Canada, the knife is amongst the stabbing weapons most frequently used in the commission of violent crimes, particularly homicides. Although under-exploited, the search for fibres resulting from contact between a textile material and a receiver surface can provide relevant information on the activity at their origin. Although cotton-polyester blended textiles are among the most commonly produced worldwide, no research seems to focus on studying the proportions of fibres transferred to the knife blade during such an attack which constitutes an important lack of information for practitioners in the field. This study involved the construction of a stabbing simulation device that performed perforations under controlled parameters (e.g. force, speed and orientation of perforation) with the use of two kitchen knives with straight and serrated blades. Simulations were conducted on a set of four blended textiles to further investigate the transfer of cotton and polyester fibres and the correlation to donor textile characteristics. The transfer mainly lies on the properties of the fibres. Since cotton fibres are shorter, less resistant and less elastic than polyester fibres, they are favoured during transfer and can be found in greater proportion. Finally, the study provides some guidelines, including the addition of a scraping step, for the recovery of fibres from knife blades.","PeriodicalId":44383,"journal":{"name":"Canadian Society of Forensic Science Journal","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2020-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/00085030.2020.1767855","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46600159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/00085030.2020.1757586
G. Yost
Abstract A previous article in this journal traced the evolution of the law from the first amendment to the Criminal Code related to breath testing for alcohol in 1951 to the Supreme Court of Canada’s decision in November 2012 on the constitutionality of the 2008 Criminal Code amendments that eliminated the “two beer” defence. This article discusses the legal, scientific and parliamentary response to that decision leading up to the 2018 decision of the Supreme Court of Canada on whether maintenance records could constitute evidence that the approved instrument had malfunctioned.
{"title":"Evidential breath testing for alcohol, Parliament, the science and the courts (Part 2)","authors":"G. Yost","doi":"10.1080/00085030.2020.1757586","DOIUrl":"https://doi.org/10.1080/00085030.2020.1757586","url":null,"abstract":"Abstract A previous article in this journal traced the evolution of the law from the first amendment to the Criminal Code related to breath testing for alcohol in 1951 to the Supreme Court of Canada’s decision in November 2012 on the constitutionality of the 2008 Criminal Code amendments that eliminated the “two beer” defence. This article discusses the legal, scientific and parliamentary response to that decision leading up to the 2018 decision of the Supreme Court of Canada on whether maintenance records could constitute evidence that the approved instrument had malfunctioned.","PeriodicalId":44383,"journal":{"name":"Canadian Society of Forensic Science Journal","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/00085030.2020.1757586","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44303910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/00085030.2020.1748284
Rhonda L. Smith, M. Kannemeyer, Emily Adams, Vinh Phu Nguyen, Ryot Munshaw, Wesley S. Burr
Abstract The present adversarial system is often criticised for not working as well as it should in the area of expert scientific testimony. Yet scientific opinion evidence is an important aspect of present criminal trials. In addition to issues in the provision of expert evidence, triers of fact are challenged to understand complex scientific evidence. Several dynamics are at play that may impact on their ability to focus on and comprehend the science, and alternative models have been suggested to address these issues, including the use of court-appointed experts. This study examines juror focus on the science versus the persona/demeanour of the expert witness between the adversarial and court-appointed models for presentation of scientific evidence. Findings suggest that expert persona/demeanour continues to be a large focus area for jurors, that the CA model may be more resilient for ensuring greater focus on science, and that juror comprehension of science is somewhat better when presented via the court-appointed model. Results inform instruction of experts for giving opinion evidence as well as suggest the prudence of considering other models to improve the criminal justice system. Limitations as to the generalization of study results are discussed.
{"title":"Comparing jury focus and comprehension of expert evidence between adversarial and court-appointed models in Canadian criminal court context","authors":"Rhonda L. Smith, M. Kannemeyer, Emily Adams, Vinh Phu Nguyen, Ryot Munshaw, Wesley S. Burr","doi":"10.1080/00085030.2020.1748284","DOIUrl":"https://doi.org/10.1080/00085030.2020.1748284","url":null,"abstract":"Abstract The present adversarial system is often criticised for not working as well as it should in the area of expert scientific testimony. Yet scientific opinion evidence is an important aspect of present criminal trials. In addition to issues in the provision of expert evidence, triers of fact are challenged to understand complex scientific evidence. Several dynamics are at play that may impact on their ability to focus on and comprehend the science, and alternative models have been suggested to address these issues, including the use of court-appointed experts. This study examines juror focus on the science versus the persona/demeanour of the expert witness between the adversarial and court-appointed models for presentation of scientific evidence. Findings suggest that expert persona/demeanour continues to be a large focus area for jurors, that the CA model may be more resilient for ensuring greater focus on science, and that juror comprehension of science is somewhat better when presented via the court-appointed model. Results inform instruction of experts for giving opinion evidence as well as suggest the prudence of considering other models to improve the criminal justice system. Limitations as to the generalization of study results are discussed.","PeriodicalId":44383,"journal":{"name":"Canadian Society of Forensic Science Journal","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/00085030.2020.1748284","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44356568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/00085030.2020.1753277
J. Lau, Jorge Frasca, M.L. Nicholson, N. Laurin
Abstract Acid phosphatase detection using fast blue or fast black reagent is routinely performed at the RCMP National Forensic Laboratory Services as a presumptive test for semen. In training exercises, samples consisting of semen mixed with blood were reported to yield negative results with the fast black reagent. To determine the cause of the inhibition, mixed semen-blood stains were prepared using different blood sources, anti-coagulants, and layering techniques, before being tested with the fast blue or the fast black reagent. The anti-coagulant sodium fluoride (NaF) was shown to cause false negative results with the fast black reagent and to impair detection when using the fast blue reagent while no inhibition was observed when dipotassium EDTA (K2 EDTA) was used as anti-coagulant. Four different toothpastes containing fluoride were also tested for potential inhibition of semen detection. Inhibition was observed when semen was mixed with three of the undiluted toothpastes but not with diluted toothpastes (1 in 20 in water). These findings highlight the importance of using appropriate blood sources when preparing mixed semen-blood stains for the purpose of training and proficiency testing in a forensic laboratory. However, forensic casework samples are not expected to contain NaF at the inhibiting levels.
{"title":"Inhibition of acid phosphatase detection in mixed semen-blood training samples by anti-coagulants present in blood collection tubes","authors":"J. Lau, Jorge Frasca, M.L. Nicholson, N. Laurin","doi":"10.1080/00085030.2020.1753277","DOIUrl":"https://doi.org/10.1080/00085030.2020.1753277","url":null,"abstract":"Abstract Acid phosphatase detection using fast blue or fast black reagent is routinely performed at the RCMP National Forensic Laboratory Services as a presumptive test for semen. In training exercises, samples consisting of semen mixed with blood were reported to yield negative results with the fast black reagent. To determine the cause of the inhibition, mixed semen-blood stains were prepared using different blood sources, anti-coagulants, and layering techniques, before being tested with the fast blue or the fast black reagent. The anti-coagulant sodium fluoride (NaF) was shown to cause false negative results with the fast black reagent and to impair detection when using the fast blue reagent while no inhibition was observed when dipotassium EDTA (K2 EDTA) was used as anti-coagulant. Four different toothpastes containing fluoride were also tested for potential inhibition of semen detection. Inhibition was observed when semen was mixed with three of the undiluted toothpastes but not with diluted toothpastes (1 in 20 in water). These findings highlight the importance of using appropriate blood sources when preparing mixed semen-blood stains for the purpose of training and proficiency testing in a forensic laboratory. However, forensic casework samples are not expected to contain NaF at the inhibiting levels.","PeriodicalId":44383,"journal":{"name":"Canadian Society of Forensic Science Journal","volume":null,"pages":null},"PeriodicalIF":0.4,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/00085030.2020.1753277","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46941977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-02DOI: 10.1080/00085030.2020.1736811
M. Illes, P. Wilson
Abstract Our inquiry into forensic epistemology explores the use of data types for case-specific research within three pattern interpretation disciplines. It also examines the epistemic status of practitioner case experimentation in forensic science. We developed three cases from different pattern-interpretation disciplines: a friction ridge analysis; a bloodstain pattern analysis; and a footwear impression analysis. For each case, a series of experiments were derived using three different data types: a quantitative approach (using numeric data), a qualitative approach (using image data) and a mixed-method approach (using both numeric and image data). We supplied data analyses that would be common knowledge for any academic researcher. Electronic files were compiled for each case and research method and forwarded by Qualtrics Software to forensic practitioners within the prescribed discipline. Demographic questions on practitioner education level and years of experience were included in the survey, along with open-ended comment areas. The dependent variable is the participants’ percentage confidence in providing an opinion from the data type used. ANOVA analyses indicated that the practitioners were more confident using a mixed-method data approach. No differences were found between the percentage confidence levels and discipline type. Similarly, there was no significant difference between the confidence levels and years of experience or the participants’ education level. The qualitative data analysis validated the quantitative results in that the practitioners were more confident with a mixed-method research approach.
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