Because of the small amount of DNA obtained from JBR and the techniques used , it's far more likely that JBR simply deposited DNA that she picked up (the same that was found under her fingernails) to her panties and leggings. LCN DNA is far better used to include rather than exclude suspects. Below are some excerpts from http://www.denverda.org/DNA_Documents/LCN DNA Profiling.pdf that highlight some of issues involving LCN DNA ("touch DNA") Transfer of DNA by individuals unassociated with the crime before the crime event itself is defined as adventitious transfer. When a DNA profile does not match the suspect, the following possibilities apply: a) The suspect is innocent and the perpetrator profile has been visualized. b) Cells have been transferred by an innocent individual before the crime (perpetrator has not shed cells) adventitious transfer. c) Cells have been transferred by an investigator after the crime event (perpetrator has not shed cells) contamination. Because the DNA test is very sensitive, it is not unexpected to find mixtures. If the potential origins of DNA profiles cannot be identified, it does not necessarily follow that they are relevant to this case, since transfer of cells can occur as a result of casual contact. Effectively, the strength of the LCN DNA evidence is decreased compared to conventional DNA analysis. This inevitably arises from uncertainties relating to the method of transfer of DNA to a surface and uncertainties relating to when the DNA was transferred. It is emphasized that the relevance of the DNA evidence in a case can only be assessed by a concurrent consideration of all the non-DNA evidence.