IPV - Bridging the juridical gap between scratches and DNA detection under fingernails of cohabitating partners

Intimate partner violence (IPV) is a global health issue with lifetime prevalences of physical and sexual violence against women of 12-71% in various populations. Due to its clandestine nature third party eye witnesses are scarce and prosecution of these cases has to rely on medical examination results, e.g. injury patterns of the victim and the perpetrator. Medicolegal assessment of DNA of the male partner found in fingernail specimen of the female partner after an assault is difficult since cohabitating couples are known to carry DNA of the respective partner in 17% of examined couples. In this study, male and total DNA content in fingernail specimen of 34 couples was analyzed after vigorous scratching of the male partners flank. Scratching and non-scratching fingers showed a highly significant difference in absolute and relative male DNA content allowing for the differentiation of DNA transfer caused by normal cohabitation and scratching during an assault.