Estimating the Number of Contributors to Forensic DNA Mixtures: Does Maximum Likelihood Perform Better Than Maximum Allele Count?
Article first published online: 14 SEP 2010
© 2010 American Academy of Forensic Sciences
Journal of Forensic Sciences
Volume 56, Issue 1, pages 23–28, January 2011
How to Cite
Haned, H., Pène, L., Lobry, J. R., Dufour, A. B. and Pontier, D. (2011), Estimating the Number of Contributors to Forensic DNA Mixtures: Does Maximum Likelihood Perform Better Than Maximum Allele Count?. Journal of Forensic Sciences, 56: 23–28. doi: 10.1111/j.1556-4029.2010.01550.x
- Issue published online: 3 JAN 2011
- Article first published online: 14 SEP 2010
- Received 1 June 2009; and in revised form 31 Oct. 2009; accepted 1 Nov. 2009.
- forensic science;
- DNA typing;
- likelihood estimator;
- STR loci;
- DNA mixtures;
- population subdivision;
- allele count;
- partial profiles
Abstract: Determining the number of contributors to a forensic DNA mixture using maximum allele count is a common practice in many forensic laboratories. In this paper, we compare this method to a maximum likelihood estimator, previously proposed by Egeland et al., that we extend to the cases of multiallelic loci and population subdivision. We compared both methods’ efficiency for identifying mixtures of two to five individuals in the case of uncertainty about the population allele frequencies and partial profiles. The proportion of correctly resolved mixtures was >90% for both estimators for two- and three-person mixtures, while likelihood maximization yielded success rates 2- to 15-fold higher for four- and five-person mixtures. Comparable results were obtained in the cases of uncertain allele frequencies and partial profiles. Our results support the use of the maximum likelihood estimator to report the number of contributors when dealing with complex DNA mixtures.