Pretty good over-view on “secondary transference” of epithelial cells being used in criminal cases that some deny happens and others use as a defense strategy. Clearly, it’s all in the “eye” of prosecutors and police.
Michelle Mankin’s blog.
Plus a very good, heavy with major forensic authors, professional journal article on the subject of “trace biological evidence” asking “how did it get there.” A co-author is renowned Swiss statistician Christophe Champod.