Detectives are investigating two jewelry store burglaries in the past month in St. Charles' historic district in which thieves got $150,000 in merchandise. In the most recent incident, burglars forced open a window early Friday at Lewis & Clark Jewelers, 724 South Main Street, smashed the tops of two glass display cases and took about 40 men's rings estimated to be worth $100,000. On July 19, burglars broke a window at Master'sPieces Fine Jewelry & Gifts, 816 South Main Street, and took $50,000 in jewelry from a display case, police said. St. Charles police Lt. Mike Akers said that in both cases, police were notified by an alarm system and responded within minutes. "Apparently, the suspects were in and out quickly and knew what they wanted," he said.