An FBI agent has been charged with exceeding his authorization in obtaining information that was used to tip off an informant, authorities said Wednesday. William Shirk, 37, had investigated a corruption case, but was removed in February 2006. He is accused of subsequently accessing a database, learning that other agents discovered the informant’s involvement in narcotics trafficking and money laundering. Shirk allegedly told the informant he had “taken care” of the investigation. He faces up to five years in prison. — DK