A letter containing a white, powdery substance received at the Richard B. Russell federal building in Atlanta Friday may have come from the same person who sent two such letters to The Herald Gazette, which arrived Thursday and Friday.”They think it is the same guy,” a source said.Atlanta coverage from http://www.myajc.com/news/news/white-powder-found-at-federal-building/nYxXp/A letter containing a white, powdery substance was found Friday evening at the Richard B. Russell federal building, the U.S. Marshals Service said.Mail room workers discovered the letter shortly after 7 p.m. and the building was evacuated, Deputy Gretchen Fortin said Friday night. The Atlanta fire department was called and a hazardous materials team was dispatched to the building, located on Spring Street.’The substance is being tested by the FBI and the results will not be received until Monday,’ Fortin said in an emailed statement.Details regarding who the letter was intended for were not released.Three Marshal Service employees were transported to Grady Memorial Hospital as a precautionary measure, Fortin said. No one was injured, she said.A portion of Spring Street and Martin Luther King Jr. Boulevard were temporarily closed while investigators removed the letter. The building was decontaminated and re-opened, Fortin said.