I feel like I may be missing something....are they performing MS analysis on the powdered COPY of the fingerprint or are they analysing the actual fingerprint (

I feel like I may be missing something....are they performing MS analysis on the powdered COPY of the fingerprint or are they analysing the actual fingerprint (and presumably the actual item that was touched and has the invisible fingerprint physically on it)? If the former, then I'm not sure how they're getting accurate results.....if the latter....that could be complicated if it's a piece of furniture or something larger than the chamber used in the MS analysis.....