I'm glad you found it easy to follow, @agmoore! And that's an interesting question. I would say that it might not be very useful for criminal forensic right now, because the soil or water sample would probably include lots of people who are not involved, so it would probably give a lot of false-positives in its current state.

As for surveillance, I would guess that it could have some potential, but we're still a pretty long way from being able to use this tool for this purpose. It is probably also a lot less effective compared to using more commons means of surveillance.

Thanks for stopping by with some very interesting questions, @agmoore! I'm sorry I could not really give you a better answer though.