Its not clear to me how this would be useful for nefarious purposes. Surely, to apply this detergent and collect the resulting biomarkers in a controlled fashi

Its not clear to me how this would be useful for nefarious purposes. Surely, to apply this detergent and collect the resulting biomarkers in a controlled fashion, they would require fairly complete access to the target individual? As in, the target would have to be sitting there letting an agent rub their arm with some swabs. And there have to be easier ways to do the same thing- file a sharp edge into the back of a door handle could likely get enough skin cells to extract DNA, without being too obtrusive. Am I missing something?