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NCJRS Abstract

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NCJ Number: 222069 Find in a Library
Title: Interpretation of Complex DNA Profiles Using Empirical Models and a Method to Measures Their Robustness
Journal: Forensic Science International: Genetics  Volume:2  Issue:2  Dated:March 2008  Pages:91-103
Author(s): Peter Gill; James Curran; Cedric Neumann; Amanda Kirkham; Tim Clayton; Jonathan Whitaker; Jim Lambert
Date Published: March 2008
Page Count: 13
Type: Report (Technical)
Format: Article
Language: English
Country: United States of America
Annotation: This paper presents a new methodology in reporting complex DNA profiles using likelihood ratios; applying a low copy number (LCN) interpretation framework.
Abstract: The method described not only calculates the strength of evidence when the suspect is a contributor to the DNA profile, but it also calculates the strength of evidence when the suspect is not a contributor to the crime stain. There is no longer a need for an ‘inconclusive’ category for reporting purposes that is based on perceived complexity of the result. In principle, any profile, with any number of contributors, can be probabilistically evaluated against any set of hypotheses. The framework is provided to incorporate all alleles into the calculation without the need to specifically assign all of them to specific contributors or to stutter artifacts. This new method determines whether proposed improvements to models are effective or worthwhile. A number of different theories are brought together in order to devise a new protocol to interpret complex cases using likelihood ratios. The calculations are designed to be highly conservative and are widely applicable. A low copy number (LCN) interpretation framework is applied which includes the probabilities of dropout and contamination, to conventional DNA cases. By increasing the number of potential contributors to the DNA profile, the extra alleles that result can be accounted for. To accomplish this, a new kind of case-specific ‘Tippett’ test is applied. The method is easily extended to carry out ranked likelihood ration searches for suspects in national DNA databases. Tables, figures, appendix A, and references
Main Term(s): DNA fingerprinting; Models; Research methods
Index Term(s): Crime laboratories; Evidence identification; Forensic medicine; Forensic sciences
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