Earlier quoted context omitted.
Fingerprints aren't even particularly useful here. Our irises are considerably more information-dense, accessible and stable over time as evidenced by the famous identification of Sharbat Gula: https://www.cl.cam.ac.uk/~jgd1000/afghan.html A close-up photo should be enough to reliably identify a person years after they went missing.
Did not know that! How easily can irises be identified in person, though? Has a handheld scanner been developed yet? Fingerprints can also be left on objects, which can be helpful for tracking someone.
Yes - I used one as far back as in 2010 on a science fair where we enrolled people to a research database.
A phone camera close-up should be enough in the right conditions, but additionally Samsung's Galaxy line used to include and iris scanner, which was just a near-infrared LED and a camera.