I can easily believe that the hair strands like a ring of a tree, can show diet changes over time. But how can they single out with such astonishing accuracy where the person had been? I would be impressed with “Went from a clean rural place to a polluted urban inner city”, but police in the UK can tell when someone had been to TAMPA by their hair? :dubious:
This is just a WAG, but I seem to recall that differences in drinking water can sometimes be used to pinpoint a person’s whereabouts from their hair (e;g some areas have a specific mineral signature).
This was Isotope Analysis. Geologists have pretty good databases of isotope distribution, as it can be used for a range of analysis. Forensic Scientists just tap in to that data.
What isotopes would they use? Organic material like hair is mostly made up of lightweight elements like carbon, hydrogen, oxygen, and nitrogen, and most of those only have one stable isotope. Do they use the trace amounts of heavier elements, or is there something useful they can get out of the common ones?