material that's there. >> using a dna test called str, or short tandem repeats, scientists found dna from three different individuals inside the mask, but investigators needed to know who was wearing the mask before it was discarded. to find out, they analyzed the swab from the ski mask to determine who left most of the saliva behind, and the results of this test were clear. >> in this case, the major contributor of dna matched that of ronald benson. >> the red ski mask was very important because it corroborated the story that we were able to receive from mrs. shaw. mrs. shaw indicated that the person with the red mask was the most aggressive in the robbery. >> the identity of the other two dna profiles in the mask was inconclusive.