Speed of accumulation of DNA in a fingermark

Variation has been reported in the amount of DNA accumulating on the skin of individuals. A shedder status is the propensity of a person to transfer DNA to a substrate by touch. In previous tests of shedders, individuals washed their hands and after 15 minutes made contact with substrates at time points up to 180 minutes after handwashing. No examination has looked at the accumulation of cellular material between time zero and this 15 minute time point. Here we present the results of an examination of cellular material within thumbprints at time points 0, 2, 5, 15 and 60 minutes after handwashing using donors who are representative of heavy, intermediate and light shedders. The rate of accumulation of cellular material and the total amount detected in thumbprints showed a difference between these donors, but for all donors the initial rate of accumulation is surprisingly fast. Informative STR profiles can be generated only 2 minutes after handwashing from 100%, 33% and none of the heavy, intermediate and light shedders, respectively. These results confirmed that there was a correlation between the cellular material present on the thumbprint and the percentage success of an STR profile for each individual and time point.