Using X-chromosomal markers in rape investigation

The X-chromosomal markers are increasingly used in forensic genetics, particularly for relationship testing. Their use has become a valuable tool in complex cases of kinship but rather in criminal caseworks is still quite rare. In this paper the authors present a case of sexual assault in which the use of X chromosome polymorphisms has been crucial. The victim was a young immigrant woman found dead in her home. The main suspect was her husband. However, the couple lived in a community in which the particular cultural context suggested the involvement of the other males of the husband family. The suspect lived together with his brother, his father and his uncle. Generally, a useful tool to solve cases of sexual violence is undoubtedly the use of Y chromosome, but in this case this device could not discriminate between the four males involved. An additional factor has further complicated the situation: the most important biological evidence (typed with AmpFlSTR Identifiler and AmpFlSTR NGM) showed a mixed profile in which was very difficult to discriminate the suspects profiles. To solve the casework, the authors typed the victim, the suspects and the biological traces with 6 X-STRs in an homemade esaplex. The results showed the presence of victim and her husband profiles in the biological trace excluding his brother, father and uncle's profiles.