Because Fs were involved, and the BATFE (pronounced "batfee") boys like to be consulted whenever crimes involve Fs. It gives them an excuse a reason to go poking around in records they're otherwise not supposed to be looking at.
Using that as a reason I would bet he had a drink or two (the A), possibly a few cigars (the T), and would the API(?) rounds he had count as E? He had the whole alphabet covered, I bet those G-Men were quivering with excitement!!!!
bob