Yeah because DUIs happen on public roads so it would go to DOT before it would go to ATF, now if that person was transporting illegal alcohol then ATF would probably get involved.
Police detectives, county personnel and federal agents spent Sunday canvassing the neighborhood near the shooting and conducting interviews with neighbors, authorities said. The FBI helped with “victim services and computer and cellphone analysis,” officials said.
Agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives were canvassing near the location of the shooting at about 3:38 p.m. when they “encountered and detained” Eaton, Burlington officials said.
Seems like they involved several agencies to canvas the area. Likely used whatever field offices were nearby. BAFTA just happened on the perp while doing so.