Officials at an art gallery say a "sophisticated" thief so carefully concealed the removal of $500,000 in small Asian works during the Asian art curator's vacation that staffers didn't realize they were gone.

The curator, Hiram Woodward, discovered upon his return that some 87 works were stolen during the vacation July 22 to Aug. 13, said Walters Art Gallery Director Robert P. Bergman, who announced the theft Thursday.Some of the objects had greater historical value to the museum than monetary value, estimated at $500,000, Bergman said.