ABSTRACT
This chapter describes the numerous factors that need to be taken into account when analyzing small amounts of DNA, as well as trace evidence transfer in general and discusses some attempt in the forensic community to determine “activity level” propositions regarding DNA transfer. The principles of DNA transfer can be extrapolated from the transfer of debris in general. The principles of transfer of trace DNA are similar to that of any forensic trace material such as fibres, paint, and glass. Locard’s Theorem or Locard’s Exchange Principle is the principle of trace evidence transfer. Trace DNA can be transferred through unknown paths, whereas transfer of visible debris has traditionally been able to be followed through different, accepted, pathways. The persistence and preservation of DNA depends on the quality and quantity. Non-self DNA can arrive on hands via direct transfer from other skin surfaces, or indirectly from contact with a surface on which DNA is present.
