In recent years, forensic science has seen a number of significant improvements in the field of forensic DNA analysis. One of the drivers has been the need to detect ever decreasing amounts of DNA. The DNA17 technique, in routine use in the UK since July 2014, is much more sensitive than its predecessor SGMPlus, and therefore the spotlight is shining brightly on the issues around DNA transfer and persistence.
What does the presence of an individual’s DNA on an item related to a crime actually mean in the context of the case circumstances? The presence of a DNA match to a suspect’s profile tells you nothing about how or when the DNA got there. Scenarios incorporating multiple DNA transfer steps, rather than a single direct transfer, are increasingly being raised in court as potential means for the presence of the defendant’s DNA at the crime scene or on an evidential item.