Jornal de pesquisa forense

A Mixed DNA Profile Controversy

Abstract

Marie Semaan, Abbas Sarah and Issam Mansour*

The DNA trace has been playing a crucial role in identifying or exonerating potential suspects. While single source DNA traces face interpretational challenges, the evaluation of a forensic DNA mixture trace faces much greater challenges especially with increased allele sharing and homozygosity. The present report describes a challenging case where eight potential suspects could not be excluded in a simulated mixed DNA analysis. Even though relevant frequency datasets and an inbreeding coefficient were considered and expert DNA mixture analysis software was used, statistical analysis falsely supported the inclusion of non-contributors. The present case shed the light on the effect of allele sharing and homozygosity on the evaluation of DNA mixtures especially in consanguineous and endogamous populations. Recommendations as to DNA mixture analysis were issued for local forensic uses and for other similar populations.