Spelling suggestions: "subject:"forensic science"" "subject:"orensic science""
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The effect of latent fingerprint processing on the recovery of gunshot primer residue particles from latex glovesJenquine, Kelsie Lynn 12 June 2019 (has links)
Gunshot primer residue (P-GSR) is released from the openings of a firearm when it is discharged12,13. P-GSR is made of microscopic particles that are considered characteristic of being derived from firearm ammunition when composed of barium (Ba), lead (Pb), and antimony (Sb) and have the correct morphology4. Morphology describes the shape of the P-GSR particle, which can be spherical, irregularly shaped, and must be non-crystalline. Forensic labs are commonly requested to test for the presence of P-GSR on evidential items, such as hands, clothing, vehicles, and gloves, in order to provide circumstantial evidence showing that they were, in some way, possibly involved with a shooting. Occasionally these evidential items are also expected to undergo fingerprint processing to potentially link someone to a crime. Latex gloves are often utilized in the commission of a crime with the impression that fingerprints cannot be left behind, however latent prints can often be developed on this non-porous material. Due to the evidential value of fingerprints and in order to ensure that potential prints are not damaged during P-GSR collection, latent print development is routinely performed first. Considering that P-GSR particles are easily dislodged, it is possible that some loss of P-GSR may occur during latent print processing.
The purpose of this study was to evaluate the effect of processing a non-porous item for latent fingerprints on the subsequent recovery and detection of P-GSR. Latex gloves were worn during the discharge of either a pistol or a revolver and then processed for latent prints by undergoing cyanoacrylate fuming followed by either white powder or yellow dye. The latex gloves were then sampled for P-GSR using aluminum stubs containing an adhesive coating which were dabbed over the gloves until they loss their tackiness. The stubs were then carbon coated using a Denton Vacuum Desk IV in order to prevent charging in the analytical instrument. Utilizing a JEOL JSM-6460LV Scanning Electron Microscope (JEOL USA Inc., Peabody, MA coupled with an EDAX Apollo X Analyzer (EDAX Inc., Mahwah, NJ) and EDAX Genesis GSR Software, the stubs were processed for three-component particles characteristic of P-GSR.
It was determined that P-GSR can still be recovered on latex gloves after undergoing latent print processing involving cyanoacrylate fuming followed by either white powder or yellow dye processing. Three-component particles were found on both the interior and exterior of the latex gloves after being processed for latent prints. On average, 33 P-GSR particles were found on the exterior of the gloves and four P-GSR particles were found on the interior of the gloves. Although significantly less were found on the interior of the gloves (<10), it is recommended that both sides of gloves be stubbed when collecting P-GSR for the greatest chances of collecting three-component particles if they are in fact present on a pair of gloves.
Although more particles were found on the gloves that were not processed for latent prints, a sufficient number of particles (≥3 particles) were consistently found on the latex gloves after undergoing latent print processing to provide a positive P-GSR result according to the Massachusetts State Police Crime Lab guidelines for P-GSR analysis. Therefore, this research shows that latex gloves can first be processed for latent prints and then subsequently be processed for P-GSR effectively in order to try and obtain both forms of evidence for a case.
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High-throughput analysis of contrived cocaine mixtures by direct analysis in real time/single quadrupole mass spectrometry and post acquisition chemometric analysisHorsley, Andrew Blair 12 March 2016 (has links)
Direct Analysis in Real Time (DART) ionization/mass spectrometry allows for the high throughput analysis of a wide range of materials including but not limited to: solids, liquids, powders, tablets, and plant materials. The ability to detect cocaine was established in a reproducible manner with the use of a DART ionization source (IonSense Inc., Saugus, MA) interfaced to a modified single quadrupole mass spectrometer. Development of a methodology for the detection of cocaine within contrived street quality drug mixtures involved the optimization of the ionization source, sample introduction mechanism, ion guide, and mass analysis parameters. An analytical method was created that utilized ionized helium carrier gas heated to 300°C and an automated sample introduction apparatus consisting of a Linear Rail Enclosure that holds consumable QuickStrip^TM sample cards. Ionized molecules were then fragmented by manipulation of voltage levels within the ion guide to gain more structural information prior to detection by a single quadrupole mass spectrometer.
Cocaine was detected by the modified DART/MS analytical platform and gave two peaks within the mass spectrum at m/z 304 and 182. Optimization of in-source fragmentation by manual adjustment of the skimmer focus voltage allowed for the reproducible fragmentation of cocaine and the ability to increase or decrease the amount of fragmentation seen between the two peaks detected for cocaine. With the use of fragmentation, this analytical platform can be classified as a Category A technique as defined by the Scientific Working Group for the Analysis of Seized Drugs.
The robust detection of cocaine was demonstrated for reference samples at concentrations as low as 10 ng/μL (50 ng) with high signal abundance greater than ten times the signal to noise ratio. Furthermore, the detection of cocaine at 10 ng/μL was demonstrated for multi component mixtures of up to 14 additional components containing common adulterants and diluents found within street quality samples. In total, 25 common excipients were tested using the same method parameters as optimized for cocaine analysis. Of these 25 excipients tested, five were not detected in positive ion mode (one could be detected in negative ion mode). Of the twenty excipients that could be detected by mass spectrometry, two pairs of excipients (levamisole/tetramisole and creatine/creatinine) could not be differentiated from each other. There were no excipients tested that had equivalent m/z values as those of cocaine. Experimentation into the effects of various excipients at multiple concentrations on the abundance of the two cocaine peaks was performed. Regardless of excipient amount (up to 10 times more concentrated than cocaine) and the number of components (up to 15 total components) the ratio of abundance between the m/z 304 to 182 peaks did not vary greater than 22% relative standard deviation.
A match criteria protocol was developed for the ability of an analyst to confirm the presence of cocaine within unknown forensic case samples that have previously tested positive for the presumptive identification of cocaine. The identification of cocaine was based on various factors such as the signal to noise ratio at m/z 304 and 182, the ratio of abundance between those two peaks as well as positive and negative controls. This match criteria protocol was utilized for 25 double blind mock forensic casework samples was performed. Determination for the presence of cocaine within these unknown samples gave an analyst error rate of 0%, with no false positives or false negatives predicted.
To further aid human interpretation and identification of compounds within mixtures, the advanced chemometric software, Analyze IQ, was utilized. Development of predictive classification models using a combination of pre-processing steps, principle component analysis and machine learning techniques was achieved. Models were built using 381 unique samples for the purposes of identifying the presence of cocaine within unknown samples. Of all methods available within the Analyze IQ software, the optimization of a model using principle component analysis with support vector machine regression with a radial basis function kernel yielded an initial error rate of 0% for 72 samples tested. Furthermore, of the samples tested against the model, 20 samples were comprised of excipients that were not incorporated into the initial model development process. The inclusion of these samples (10 spiked with cocaine, 10 absent of cocaine), shows that predictive modeling based software can provide an accurate, robust, and evolving approach to the identification of cocaine within sample compositions that have not previously been tested and stored in a database of known reference samples. Predictive modeling has advantages over current mass spectral libraries, which are limited to the identification of pure compounds. To further test the abilities of predictive models, optimized machine learning models were applied to 25 double blind mock forensic casework samples. The predictive modeling error rate was identical to the human interpretation rate for the double blind mock casework samples with a 0% error rate.
Using the DART/MS analytical platform, 25 mock forensic casework samples along with positive and negative controls were analyzed and identified for the presence of cocaine within 30 minutes. On the order of 15 to 30 times faster than modern GC/MS and LC/MS methods, the ability to analyze and identify samples faster would allow for an increase in samples being processed on a daily basis and allow for the reduction of case backlogs that currently plague controlled substances sections of forensic science laboratories throughout the United States.
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Using eye-tracking, head-mounted camera technology and verbal protocol analysis as a methodology to better understand Volume Crime Scene Investigator practiceButler, Mark January 2014 (has links)
Literature Review: Expertise, decision making and situation awareness literature have allowed a better understanding of practitioner performance in Engineering, Healthcare and Sport. Discourse is thin in the domain of Crime Scene Examination, although Hierarchical Tasks Analysis, Distributed Cognition, Team Working and Perception have all received attention in recent years. The use of camera technology to uncover performance has also found footing in diverse professions, notably Firefighting and Social Work. Crime Scene Investigator practice is proposed as being a fertile area of study, to make apparent aspects of the work that are tacit, as well as to ascertain if performance metrics in the sector connect with the tacit knowledge expressed in the role. Methodology: This study explored the differences in searching strategies between expert and novice Crime Scene Examiners (n=12) in a simulated environment, before discussing a longitudinal ethnographic examination of how Volume Crime Scene Investigators (n=4) make sense of their practice. Eye-tracker and head-mounted camera technology was used to capture performance from an own point of view perceptive. Nvivo 9 was utilised to collate and code video data, field notes and interview transcriptions. Results & Discussion: Results from verbal protocol analysis and eye-tracker recordings indicate that expert examiners target fewer objects within the crime scene space however spend longer on the objects being viewed. Field study results report that Volume Crime Scene Investigators engage in sharing tacit knowledge, this impacted on their strategies or perception of obtaining forensic evidence. In addition the analysis of coded data from video and verbal protocol reports found that specific physical aspects of examination practice such as fingerprint powdering were aligned to decision making or analysis processes. For example, commenting on the morphology of the surface being examined. Furthermore examiners engaged in and highlighted aspects of their role they felt were important but were not captured in any metrics. Conclusion: It is proposed this new understanding will be of use to those in developing crime scene investigation practitioners as well as presenting related literature on how expertise in the domain can be recognised, elicited and developed in others. This work also sheds light on the value of sector standards for this field along with what is needed to make them more user- friendly for the developing practitioner.
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Police PhotographyMiller, Larry S., Marin, Norman 01 January 2015 (has links)
Quality photographs of evidence can communicate details about crime scenes that otherwise may go unnoticed, making skilled forensic photographers invaluable assets to modern police departments. For those seeking a current and concise guide to the skills necessary in forensic photography, Police Photography , Seventh Edition, provides both introductory and more advanced information about the techniques of police documentation. Completely updated to include information about the latest equipment and techniques recommended for high-quality digital forensic photography, this new edition thoroughly describes the techniques necessary for documenting a range of crime scenes and types of evidence, including homicides, arson, and vehicle incidents. With additional coverage of topics beyond crime scenes, such as surveillance and identification photography, Police Photography , Seventh Edition is an important resource for students and professionals alike. / https://dc.etsu.edu/etsu_books/1060/thumbnail.jpg
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Forensic Investigation of Sex Crimes and Sexual OffendersBurkey, Chris Rush, Bensel, Tusty ten, Walker, Jeffery T. 24 November 2013 (has links)
The investigation of sex crimes is a specific function for many law enforcement agencies, requiring an understanding of how to investigate, process crime scenes, interact with victims and offenders, and prepare for court. Drawing on new methods of investigation and the effects of such crimes on victims, Forensic Investigation of Sex Crimes and Sexual Offenders provides in-depth coverage in these areas, offering a valuable supplement for criminal justice courses and an accessible guide for law enforcement. / https://dc.etsu.edu/etsu_books/1134/thumbnail.jpg
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Detection of gasoline from internal tissues for use in determining victim status at the time of a firePahor, Kevin 01 August 2012 (has links)
In Ontario, fire investigators from the Office of the Fire Marshal (OFM) are responsible for determining the origin and cause of suspicious fires. As part of the investigation, fire debris samples are collected from the scene and analyzed by the Centre of Forensic Sciences. The standard practice is to collect items that are porous, highly absorbent or adsorbent with high surface areas as they allow for better retention of the ignitable liquids. The evidence typically collected includes carpets, cardboards, soils, cloths and other items that have not been impinged by flame such as beneath baseboards. These samples are analyzed for the presence of ignitable liquid residues which may be evidence that an accelerant was used at the fire. When a body is recovered from a fire it can provide another source from which to collect samples for analysis. These samples can be especially helpful in instances where the fire generated an intense heat which may cause a loss of ignitable liquid residues from the fire debris. The tissue samples have a greater likelihood of still containing residues as the organs and body fluids can act as a shield protecting the residues from volatilization.
The purpose of this study is to validate whether a victim was alive or deceased at the time a fire was intentionally set by detecting presence or absence of gasoline residues within their lungs and heart blood post fire. It was hypothesized that only when a victim was alive and performing respiration would sufficient gasoline vapours enter the airways and bloodstream for detection postmortem. Contamination becomes a significant issue when these samples are collected at autopsy and this study aimed to determine the accuracy with which a gasoline signature can be interpreted following the collection and analysis of lung tissue and heart blood.
Pig (Sus domesticus) carcasses were chosen as acceptable analogues for humans in this study. The experiments involved anaesthetizing a pig (with Animal Ethics Approval), exposing the pig to gasoline vapours for 10 minutes, and then euthanizing it. The carcass was clothed with a cotton t-shirt and placed in a house where additional gasoline was poured onto it. The house also contained two additional clothed pig carcasses which did not inhale gasoline vapours; one with gasoline poured directly onto it and the other with no gasoline exposure (negative control). Thermocouples were placed under each carcass and in the centre of each room at ceiling and floor level to record the temperature. The house was set ablaze and monitored by a volunteer fire service. After the fire had reached
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flashover and was suppressed, the carcasses were collected and their lungs and heart blood excised at a necropsy. The lungs and heart blood were then placed into glass mason jars following the OFM protocol. The headspace from each sample was analyzed by thermal desorption-gas chromatography-mass spectroscopy to determine the presence or absence of a gasoline signature. Two full scale house fires were conducted in order to obtain three replicates.
The results showed that only the lungs and heart blood from the pig that inhaled gasoline contained gasoline residues. This indicates that it is possible to determine a victim’s status at the time of the fire based on the detection of gasoline in the lungs and/or heart blood. It was also concluded that contamination of samples during an autopsy can be minimized by changing gloves before handling the internal tissues. The thermal data showed that the bodies act as an insulator and protects the underside as the temperatures under the carcasses did not exceed 30⁰C while the room reached over 900⁰C at the first full scale house fire.
These results will impact the forensic community by demonstrating the importance of analyzing a deceased victim’s internal tissues for ignitable liquid residues post fire as they may provide evidence of an intentionally set fire as well as providing information about the victim’s status when a fire was started. These findings will have a direct impact to the OFM as additional evidence can be obtained by completing internal tissue analysis. This will intern impact the Centre of Forensic Science (CFS) as it confirms the importance of analyzing internal tissues in order to provide results to fire investigators. Finally these findings should be used to implement new protocols at the Coroner’s Office so contamination can be minimized during fire autopsies and accurate samples are collected and sent to the CFS for analysis. / UOIT
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Image Enhancement over a Sequence of ImagesKarelid, Mikael January 2008 (has links)
This Master Thesis has been conducted at the National Laboratory of Forensic Science (SKL) in Linköping. When images that are to be analyzed at SKL, presenting an interesting object, are of bad quality there may be a need to enhance them. If several images with the object are available, the total amount of information can be used in order to estimate one single enhanced image. A program to do this has been developed by studying methods for image registration and high resolution image estimation. Tests of important parts of the procedure have been conducted. The final results are satisfying and the key to a good high resolution image seems to be the precision of the image registration. Improvements of this part may lead to even better results. More suggestions for further improvementshave been proposed. / Detta examensarbete har utförts på uppdrag av Statens Kriminaltekniska Laboratorium (SKL) i Linköping. Då bilder av ett intressant objekt som ska analyseras på SKL ibland är av dålig kvalitet finns det behov av att förbättra dessa. Om ett flertal bilder på objektet finns tillgängliga kan den totala informationen fråndessa användas för att skatta en enda förbättrad bild. Ett program för att göra detta har utvecklats genom studier av metoder för bildregistrering och skapande av högupplöst bild. Tester av viktiga delar i proceduren har genomförts. De slutgiltiga resultaten är goda och nyckeln till en bra högupplöst bild verkar ligga i precisionen för bildregistreringen. Genom att förbättra denna del kan troligtvis ännu bättre resultat fås. Även andra förslag till förbättringar har lagts fram.
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Design, Synthesis And Electropolymerization Of A New Chemiluminescent Terthienyl SystemAtilgan, Nurdan 01 September 2008 (has links) (PDF)
ABSTRACT
DESIGN, SYNTHESIS AND ELECTROPOLYMERIZATION OF A NEW
CHEMILUMINESCENT TERTHIENYL SYSTEM
Atilgan, Nurdan
M.Sc. Department of Chemistry
Supervisor: Prof. Dr. Ahmet M. Ö / nal
Co-Supervisor: Assist. Prof. Dr. Atilla Cihaner
September 2008, 57 pages
A novel monomer, possessing chemiluminescence properties, 5,7-di-ethylenedioxythiophen-2-yl-2,3-dihydro-thieno[3,4-d]pyridazine-1,4-dione (ETE-Lum) was synthesized. Chemiluminescence properties of ETE-Lum were investigated in alkaline water solution in the presence of H2O2 and this reaction was catalyzed by Fe+3 ion and blood. This study submits a new opportunity to investigate forensic and analytical application instead of 5-amino-2,3-dihydro-1,4-phthalazine-dione (luminol). Response of other metalic cations was also investigated under the same reaction conditions. Electrochemical properties of ETE-Lum were studied in 0.1 M acetonitrile/tetrabutylammonium perchlorate solvent system containing BF3-Et2O and also in neat BF3-Et2O solution. In addition, the corresponding polymer film of ETE-Lum (PETE-Lum) was synthesized successfully via repetitive cycling by cyclic voltammetry and its electrochemical properties were investigated in a monomer-free electrolyte solution.
Spectroelectrochemical behavior of the polymer film on indium tin oxide working electrode was also investigated by recording the electronic absorption spectra, in-situ, in monomer-free electrolyte solution at different potentials. Furthermore, spectroelectrochemical studies revealed that PETE-Lum had an electronic band gap of 1.66 eV. The results of electrochemical and electroluminesence measurements indicated that chemiluminecent unit of monomer was protected during polymerization. In addition, PETE-Lum film was found to be electrochemiluminescence active, maintaining its activitiy over 1000 cycles.
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Development and Applications of Laser-Induced Acoustic Desorption/Electrospray Ionization Mass SpectrometryCheng, Sy-Chyi 27 January 2010 (has links)
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Image Enhancement over a Sequence of ImagesKarelid, Mikael January 2008 (has links)
<p>This Master Thesis has been conducted at the National Laboratory of Forensic Science (SKL) in Linköping. When images that are to be analyzed at SKL, presenting an interesting object, are of bad quality there may be a need to enhance them. If several images with the object are available, the total amount of information can be used in order to estimate one single enhanced image. A program to do this has been developed by studying methods for image registration and high resolution image estimation. Tests of important parts of the procedure have been conducted. The final results are satisfying and the key to a good high resolution image seems to be the precision of the image registration. Improvements of this part may lead to even better results. More suggestions for further improvementshave been proposed.</p> / <p>Detta examensarbete har utförts på uppdrag av Statens Kriminaltekniska Laboratorium (SKL) i Linköping. Då bilder av ett intressant objekt som ska analyseras på SKL ibland är av dålig kvalitet finns det behov av att förbättra dessa. Om ett flertal bilder på objektet finns tillgängliga kan den totala informationen fråndessa användas för att skatta en enda förbättrad bild. Ett program för att göra detta har utvecklats genom studier av metoder för bildregistrering och skapande av högupplöst bild. Tester av viktiga delar i proceduren har genomförts. De slutgiltiga resultaten är goda och nyckeln till en bra högupplöst bild verkar ligga i precisionen för bildregistreringen. Genom att förbättra denna del kan troligtvis ännu bättre resultat fås. Även andra förslag till förbättringar har lagts fram.</p>
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