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Investigation of the effect of time and Investigation of the effect of time and... - Complex Object ()
Title
Investigation of the effect of time and surface type on amplicon contamination of DNA profiles / Arwa Hashem Mohamed Al-Hanbali
Author
Year
2010
Abstract
Forensic analysis of the Deoxyribonucleic Acid (DNA) obtained from biological evidence, such as blood or cellular samples, commonly known as DNA profiling or DNA “typing”, has become an important tool for individual identification in the criminal justice system. However, the disturbing possibility of deliberate contamination of the DNA evidence at the crime scene still exists. Accidental DNA contamination is widely researched and many preventative procedures have been put in place to eliminate this form of DNA contamination. On the other hand, deliberate DNA contamination of the DNA evidence at the crime scene has not been discussed in much detail. The deliberate contamination of the DNA either by planting a person’s DNA at a crime scene or by contaminated the forensic evidence samples using another person’s DNA amplicons still exists. Both can produce misleading DNA profiles. The current study shows that the deliberate contamination of the biological samples with amplicons under simulated crime scene conditions resulted in an alteration to the DNA profile of the original genomic DNA. Not only do immediate additions of PCR amplicons to samples alter the genomic DNA profiles, amplicons remain present in the genomic DNA profiles even after a period of up to seven weeks under the conditions used in this study. However, the alteration of the genomic DNA with amplicons contamination is not obvious after a period of five weeks. Amplicons alleles were still present but there was a drop-off of fluorescence intensity of the alleles and these peaks could be dismissed as stutter peaks. The study also showed that the surface type can influence the recovery of biological samples; however, in all cases the recovery of contaminant amplicons was observed from the swabbed surfaces.
Previous studies show that the use of ‘substrate’ controls in DNA analysis has limited value (Gill, 1996) in contrast, this study suggest that swabs an area adjacent to a sample or stain at the crime scene, may be useful in detecting the presence of amplicon contamination at crime scenes. Finally this study has verified that a hair washing step before DNA extraction can eliminate amplicon contamination of hair samples.
Identifier
http://repository.uwa.edu.au:80/R/-?func=dbin-jump-full&object_id=29881&silo_library=GEN01
Subject
Department/School
Type
Thesis (M.For.Sc.)--University of Western Australia, 2010
Persistent URL
http://repository.uwa.edu.au:80/R/-?func=dbin-jump-full&object_id=29881&silo_library=GEN01
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