Is it always possible to avoid exhumation in particular defective paternity cases by increasing autosomal STRs number?

Genetic markers represent a very important tool in forensic identification caseworks, in family relationships as well as in criminal analysis. The discrimination power of current genetic polymorphisms is so high that the inferential process can be efficiently used even in cases where direct knowledge on the genetic data of one of the terms in comparison is lacking. However in some cases despite the use of Probabilistic Expert Systems (FINEX) it is not always possible to achieve an acceptable percentage of paternity probability. Certainly one of these cases is the request to verify the relationship between two half-siblings of different gender in the absence of data from parents. In these cases it is not possible to use important tools such as polymorphisms of sexual chromosomes, so that the only possible approach is to increase the number of autosomal STRs. Therefore the authors decided to investigate 36 pairs of halfsiblings with known relationships from different parts of Italy, using a high number of autosomal STRs. The aim of this study is to verify whether, increasing the number of autosomal STRs analyzed, the application of PES allows to achieve an acceptable value of paternity probability without availability of parents’ profiles.