Information on this issue provided by Tom Lammers and the Atlas/Timely discussion list.
For some reason, the museum and painting are referred to as the "Museum of Classical Art" and "The Smiling Maiden", repsectively. The thief is called "Vincenzio Leopardi," and the date of the theft given as 23 September.
Story shows considerable similarity to "The Murders in the Rue Morgue" by Edgar Allan Poe (1841).