A ‘DNA mixture’ or ‘mixed DNA result’ is one in which DNA from more than one person is present. The prevalence of DNA mixtures has escalated in recent years due to the use of extremely sensitive DNA profiling methods which can detect just a few cells.
Alongside this, the complexity of mixture results has increased as it is commonplace to detect mixtures containing DNA from three or more people, which are more difficult to interpret. With an unmixed ‘single DNA profile’ it is straightforward for the forensic expert to interpret the result and say whether the profile matches an individual or not, and to provide a statistical assessment for the match. However whilst the expert can assess whether an individual could have contributed to a complex DNA mixture result specialist statistical software is required to assess the likelihood of whether (or not) that person could have contributed to the mixture.