Interpreting DNA Mixtures With Bayesian Framework

Recently, with the development of DNA technology and human genome project, utilizing DNA evidence is becoming more and more popular in some cases' detection and trial. Sometimes DNA evidence is the only clue of some cases. So the application of DNA evidence has been increasingly emphasized. There is a question in common method in quantifying DNA evidence. Common plug-in approach neglects the sample size when evaluating the allele frequencies in a reference population whose population parameter is uncertain. That will lead to overweight DNA evidence and this is unfair to the accused man. So it is argued that the quantification of DNA evidence should reflect the sample size's influence.Firstly, this paper introduces the background of the topic and the main research work at present in the world and this paper's main content. Secondly, we discuss two types of questions, one reference population and two reference populations, and obtain the concise formula of calculating likelihood ratio LR respectively. Especially we describe the two hypotheses via graph. Taking the sample size into account we employ the Bayesian model and taking the allele frequencies as random variables. In the third chapter of this paper, we give some numerical examples separately according to the Bayesian method and the common plug-in approach. The results suggest that the former is more conservative and accurate than the latter. At last, some conclusions and comments are given.