Fire crews arrive at the unmarked postal building by the Beltway every few days, donning protective rubber suits and carrying away suspicious letters addressed to members of Congress. At a similarly secret building in the District, agents set aside letters once or twice a week to the president containing powder or other cause for concern. For years — ever since the anthrax attacks of 2001 — nearly every one has proved harmless.But alarms sounded in both buildings this week, and the threats appeared real: A grainy substance tested positive for the lethal toxin ricin in letters addressed to President Obama and a quiet senator from Mississippi.
By Wednesday night, authorities had arrested Paul Kevin Curtis of Corinth, Miss., as a suspect in the ricin mailings, the FBI said in a statement. Curtis also sent a third letter to a Mississippi justice official, the FBI said. He is well known to law enforcement as a frequent letter-writer to lawmakers, two officials said.READ MORE