Biostatistics for mixed stains: the case of tested relatives of a non-tested suspect.

Analysis of a mixed biological stain by means of highly polymorphic VNTR systems usually reveals a profile composed of multiple markers. If the victim and one or several suspects match the profile, the evidential strength of the matches has to be very carefully analysed. The appropriate methods for the statistical analysis of DNA profiles advanced recently were limited to cases with no relationship between the tested and non-tested persons. The present paper extends the theory beyond this limitation.