there was a great picture in Popular Science mag (?) a long time back, mid 50's era, maybe even before that (a found on internet thing).
It showed a couple of G-Men agents (FBI) secreted away in a building aiming the *large single tube shotgun mic at some gangsters from behind a curtain, recording what they were saying. stealth stylin'.
* If not that mic, then one very similar to it - a huge shotgun mic.