Dempsey was first identified by a group of online sleuths who used open-source video and photos to supply suspect names to the FBI, as detailed in the book “Sedition Hunters” by NBC News reporter Ryan J. Reilly. The sleuths, who initially dubbed Dempsey “FlagGaiterCopHater,” even noticed his change of outfits, but he continued to wear the same Converse high-top sneakers and camouflage pants throughout.