A systematic analysis of secondary DNA transfer

The Nature letter by R. van Oorschot and M. Jones (1) addressed two topics: the primary transfer of DNA from person to person or to various objects, a nd the secondary transfer of DNA through an intermediary. Forensic scientis ts have described the primary transfer of DNA and other biological evidence for many years. However, the authors also reported detecting secondary tra nsfer of DNA from an object to a person's hands, which could adversely affe ct DNA typing in the forensic context. The prospect of secondary transfer r aises questions of interest to both the legal and forensic communities. The refore, we sought to evaluate parameters potentially leading to secondary D NA transfer. Our data do not support the conclusion that secondary transfer will compromise DNA typing results under typical forensic conditions.