The Baltimore Sun reports tonight that the pair spent much of the day on Saturday at the historical society, and caught the attention of staff near the end of the day, when Savedoff was observed placing a document into a portfolio and leaving the reading room. Staff retrieved Savedoff's locker key and discovered the documents inside the locker, then called the FBI (who are now investigating along with the Baltimore police).
Both men have been charged with one count of theft (of materials valued at more than $100,000); more charges may be forthcoming.
The paper reports that an initial hearing in the case is set for 11 August.
Good for the staff for being watchful on this; it's nice to see a theft nipped in the bud before it happens. If this guy's been to your library, you'd better check the items he called for and make sure they're still where they belong.