A nucleic acid tag comprising a nucleotide-support platform attached to a nucleic acid molecule, an odorant, and an encapsulant. Unique nucleic acid-containing tags containing an odorant are seeded at one or more geographic locations. Using odorant-detection systems, the person or object of interest is examined for the presence of one or more of the odorant, thereby revealing the presence of the seeded nucleic acids and eliminating the expense and time associated with unnecessary screening. The geographic location associated with each detected nucleic acid is used to backtrack the item's path or extrapolate a probable point of origin.