Using the information embedded in the mixed profiles to assist in determining the identity of the deceased and the suspect in a deficiency case.

In the present case, due to the lack of database matches and available relatives, the use of single-source DNA profiles from the unidentified deceased and the suspect was not yet able to determine the identity of them, resulting in the inability to continue the investigation. However, by interpreting a simple mixture on the penile swab of the deceased and a complex mixture on the prayer flag wrapped around the ankles of the deceased, the information embedded in these two mixtures provided us with a breakthrough point for addressing the identity determination. Preliminary analysis using the separating method or based on imbalanced peaks at the Amelogenin locus revealed that each of the two DNA mixtures should have a female minor contributor, who were likely to be sex workers according to the investigation results. Consequently, blood samples from fifty-two women were collected for STR genotyping. The analysis results of the two mixtures using LRmix Studio showed that the probability of the simple mixture that if it came from the deceased and the female numbered P0053 is 4.7078 × 10 times more likely than if it came from the deceased and an unknown female, while the probability of the complex mixture that if it came from P0062, the deceased and the male suspect is 8.1777 × 10 times more likely than if it came from the deceased and two unknowns. Subsequently, based on the clues provided by P0053 and P0062, the identity of the deceased and the suspect was successfully determined and the case was finally resolved. These results suggest the valuable evidence that can be obtained from mixtures and the high priority that should be placed on the analysis of mixtures, especially those that may be considered unlikely to derive complete single-source profiles by interpretation. In addition, the occurrence of a secondary DNA transfer was confirmed.