Interpretation of simple mixtures of when artefacts such as stutters are present - with special reference to multiplex STRs used by the Forensic Science Service

The interpretation of mixtures is enhanced by taking into consideration the area of peaks. This often enables alleles to be subdivided into major and minor components. In many cases, the minor components are not of evidential value, particularly when the major bands are from the suspect, and the remaining minor bands are from the victim. In cases where the minor contribution is from the suspect, artefacts take on greater significance. In particular, bands which coincide with stutter positions need to be considered as possible artefacts or alleles. This paper outlines a method for dealing with the interpretation of mixtures when stutter artefacts are present. In principal the philosophy presented can be extended to deal with any artefact.