Mestrado em Ciências Forenses / Master Degree Course in Forensic Sciences

published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy

Volume crimes such as burglary and street robbery present an enormous cost to the Australian community each year. These ubiquitous crimes traditionally have a low resolution rate, but the use of information gathered through DNA databases provides another avenue of investigation. The forensic response to these crimes could be increased with the use of trace DNA; however the lack of awareness of forensic science as a holistic discipline focusing on the study of traces, often leads to a lack of knowledge into the trace evidence characteristics of DNA. This problem is compounded by practical and interpretive difficulties. The main hypothesis tested through this study is that, with an increased understanding into the criminalistic properties of trace DNA, it may prove to be more useful and effective evidence in the investigation of volume crime than is currently the case. The project encompassed three parts. The first component was a detailed survey sent to every jurisdiction in Australia and New Zealand to benchmark methods and protocols, education and training of personnel, and opinions and uses of trace DNA. The second involved the analysis of the results of 250 trace DNA swabs collected from New South Wales crime scenes, in order to provide a comparison point to the experimental work. The final section comprised preliminary experimental work to investigate the abundance, transfer and persistence of trace DNA within the context of residential burglary and street robbery offences. The methods survey helped to identify methods to be used in the experimental component of the project, but also highlighted issues in the field including a lack of training and proficiency testing. The absence of data collation across the jurisdictions was also a point for concern, and prevented the identification of factors that may affect trace DNA success rates. The pervading outcome of the survey was the need for effective data management systems and strong communication lines to facilitate best practice. From the analysis of the casework data a success rate in the order of 15- 20% was identified for New South Wales trace DNA swabs, with an average of 1.7ng of DNA recovered. Subsets of the data were used to directly compare to the experimental results in terms of transfer and persistence. The experimental work gave an insight into the behaviour of trace DNA in crime scene scenarios. The level of background DNA on surfaces encountered in forensic investigations was varied; for example residential doors were found to hold more background DNA than windows. Whilst the level of DNA on personal items such as bags and wallets was found to be relatively high, DNA from the offenders of simulated robberies could still be detected in usable quantities on these items. DNA was found to persist in sheltered locations for at least six weeks,but declined more rapidly in outdoor environments, with profiles not recovered after two weeks. This information may help to assist the interpretation and presentation of trace DNA evidence when the judicial question is one of activity, rather than source. The data also may be used in the education of crime scene examiners to assist them to target the most probative evidential samples. With further work in this field, trace DNA will be more easily applied to investigations. Trace DNA may be a useful tool in volume crime investigations, but individual jurisdictions should assess their capacity to manage the evidence to ensure results can be disseminated and actioned in a timely manner, otherwise the investment may prove to be fruitless. Effective and ongoing training programs and functional data management systems should be implemented to maximise both the investigative and intelligence value of trace DNA evidence. A holistic approach to the implementation of forensic evidence, encompassing the groundwork of theoretical analysis, review of capabilities and logistical and technical improvements, would greatly increase its value in policing and the criminal justice system.

Volume crimes such as burglary and street robbery present an enormous cost to the Australian community each year. These ubiquitous crimes traditionally have a low resolution rate, but the use of information gathered through DNA databases provides another avenue of investigation. The forensic response to these crimes could be increased with the use of trace DNA; however the lack of awareness of forensic science as a holistic discipline focusing on the study of traces, often leads to a lack of knowledge into the trace evidence characteristics of DNA. This problem is compounded by practical and interpretive difficulties. The main hypothesis tested through this study is that, with an increased understanding into the criminalistic properties of trace DNA, it may prove to be more useful and effective evidence in the investigation of volume crime than is currently the case. The project encompassed three parts. The first component was a detailed survey sent to every jurisdiction in Australia and New Zealand to benchmark methods and protocols, education and training of personnel, and opinions and uses of trace DNA. The second involved the analysis of the results of 250 trace DNA swabs collected from New South Wales crime scenes, in order to provide a comparison point to the experimental work. The final section comprised preliminary experimental work to investigate the abundance, transfer and persistence of trace DNA within the context of residential burglary and street robbery offences. The methods survey helped to identify methods to be used in the experimental component of the project, but also highlighted issues in the field including a lack of training and proficiency testing. The absence of data collation across the jurisdictions was also a point for concern, and prevented the identification of factors that may affect trace DNA success rates. The pervading outcome of the survey was the need for effective data management systems and strong communication lines to facilitate best practice. From the analysis of the casework data a success rate in the order of 15- 20% was identified for New South Wales trace DNA swabs, with an average of 1.7ng of DNA recovered. Subsets of the data were used to directly compare to the experimental results in terms of transfer and persistence. The experimental work gave an insight into the behaviour of trace DNA in crime scene scenarios. The level of background DNA on surfaces encountered in forensic investigations was varied; for example residential doors were found to hold more background DNA than windows. Whilst the level of DNA on personal items such as bags and wallets was found to be relatively high, DNA from the offenders of simulated robberies could still be detected in usable quantities on these items. DNA was found to persist in sheltered locations for at least six weeks,but declined more rapidly in outdoor environments, with profiles not recovered after two weeks. This information may help to assist the interpretation and presentation of trace DNA evidence when the judicial question is one of activity, rather than source. The data also may be used in the education of crime scene examiners to assist them to target the most probative evidential samples. With further work in this field, trace DNA will be more easily applied to investigations. Trace DNA may be a useful tool in volume crime investigations, but individual jurisdictions should assess their capacity to manage the evidence to ensure results can be disseminated and actioned in a timely manner, otherwise the investment may prove to be fruitless. Effective and ongoing training programs and functional data management systems should be implemented to maximise both the investigative and intelligence value of trace DNA evidence. A holistic approach to the implementation of forensic evidence, encompassing the groundwork of theoretical analysis, review of capabilities and logistical and technical improvements, would greatly increase its value in policing and the criminal justice system.

This study proposes the classification of the toolmark under the heads of zipper teeth as a subclass characteristic as outlined by the Association of Firearm and Toolmark Examiners (AFTE). Two separate cases in which zipper teeth were found at crime scenes prompted this study. Brass zipper teeth manufactured by YKK were taken from 20 pairs of jeans and studied using a Reichert comparison microscope at 4X power. Photographs were taken and over 750 comparisons made. It was found that the toolmarks on each side on the 20 zippers were unique and independent of all other sides. The observations made in this study indicate that classifying zipper teeth toolmarks as a subclass characteristic is valid.

Several factors that influence the rate of human decomposition have been described in the literature, including temperature, access by insects, humidity and rainfall1. These environmental factors, as well as purge fluid released during decomposition2, can interact with evidence deposited on the clothing of a deceased individual. The present research assessed how these combined factors affect the detection and identification of blood and semen evidence, as well as subsequent DNA analysis. A 35-45 pound (lb) feeder pig (post-mortem interval (PMI) < 3 hours) was placed on a grassy area within the Boston University Outdoor Research Facility for a period of 22 days or 364.3 accumulated degree days (ADD) during late spring, with the temperature averaging 16.5 oC. Aliquots of 30 μl of either human blood or semen were pipetted onto 1 inch by 1 inch sections of a 95% cotton t-shirt. Twenty-two samples of each type were placed on top of and underneath the pig, as well as a similarly weighted bag of sand (control). One bloodstain and one semen stain were collected each day for a period of 22 days from each location, yielding 8 samples per day. Each sample was analyzed within 30 hours of collection. The blood samples beneath the control showed that environmental factors influenced the results of testing. Rain caused dilution and diffusion of the bloodstains and the color of the stains changed from red-brown to green-yellow. Kastle-Meyer (KM) testing was positive for all samples and ABAcard® HemaTrace® testing was positive for 14 of 22 samples, with the negative results occurring during days 12 - 21. Two stains that were negative at 10 minutes turned positive shortly thereafter, suggesting that a longer development time may be required for compromised samples. The blood samples placed beneath the pig yielded positive KM results on all 22 days and positive HemaTrace® results through day 10. All bloodstains placed on top of the pig and control yielded positive KM and HemaTrace® results. The blood samples from on top of the pig and control yielded full short tandem repeat (STR) profiles for each of the four days of testing (days 1, 8, 13 and 20). The blood samples from beneath the pig and control yielded full profiles on day 1 only. The three subsequent days of testing yielded a maximum of three alleles per sample, with the majority of samples failing to provide any profile at all. Semen samples from beneath the control began to show a decrease in fluorescence using an alternate light source (ALS) by day 3, and some areas of fluorescence occurred in a different location, indicating that the soluble components had diffused outward from the original region of deposition (ORD). Results for acid phosphatase (AP) and ABAcard® p-30 were mostly positive through day 16. By day 17, the ORD no longer fluoresced or yielded positive AP or p-30 results. With the exception of day 10, sperm were identified on all samples. Semen results from beneath the pig showed that even on day 1, the ORD was only weakly fluorescent and by day 4, fluorescent regions began appearing outside of the ORD. These outlying regions of fluorescence yielded positive results with AP Spot and p-30 testing, but showed few or no spermatozoa when examined microscopically. As the days passed, the ORD were no longer fluorescent and AP mapping and p-30 testing yielded negative results; however, spermatozoa could still be identified in almost all of the ORD through day 22. Semen samples collected from on top of the control showed that semen stains retained fluorescence and tested positive for AP, spermatozoa and p-30 through 22 days of testing. Semen samples collected from on top of the pig yielded similar results until day 16, when the fluorescence began to fade and AP testing did not yield traditional color changes associated with a positive result. By day 18, fluorescence was no longer visible with an ALS at 450 nm or 495 nm, however, UV light yielded positive fluorescence when used during days 19-21. Spermatozoa and p-30 were identified on samples saturated with products of decomposition, even when presumptive screening techniques were negative (450-495 nm) or showed an altered appearance (AP). Semen samples from within the ORD yielded full 16 loci profiles from beneath the pig and both on top of and beneath the control on each of the four days of testing. The samples collected from on top of the pig yielded full profiles on days 1, 6 and 14 and partial profiles on day 20. Samples from beneath the pig on days 6 and 14, which had positive presumptive results outside of the ORD, were also amplified, but failed to yield a profile.

Thesis (M.A.)--Texas State University-San Marcos, 2008. / Vita. Appendices: leaves 74-79. Includes bibliographical references (leaves 80-84). Also available on microfilm.

Thesis (M.S.)--Michigan State University. School of Criminal Justice , 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references (p. 42-45). Also issued in print.

Thesis (M.S.)--West Virginia University, 2005 / Title from document title page. Document formatted into pages; contains x, 128 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 127-128).

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xii, 88 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 87-88).