Saturday Morning's Forgotten Heroes: Atom Ant vs. Fancy Finger Finnegan (Gem-A-Go-Go, 1965)
Atom Ant battles the infamous jewel thief, Fancy Finger Finnegan, in the episode, "Gem-A-Go-Go". Study Finnegan's voice patterns. Sounds like it might be Daws Butler doing a cross-impersonation of Edward G. Robinson and maybe Don Adams, whose Get Smart, was also on NBC at the time.
Too big for the local police? Any excuse to have Atom embarrass an ordinary human thief.