A bail hearing for Landau is to be held today; his accomplice, Jason Savedoff, is currently out on $250,000 bail. The pair were indicted by a federal grand jury in Baltimore on 28 July; an FBI press release notes that the indictment covers the thefts from the FDR Library, the New-York Historical Society, and the Maryland Historical Society.
The investigation is ongoing, and I suspect there are more shoes yet to drop.