Letters sent to President Barack Obama and a U.S. senator tested positive for poisonous ricin in preliminary checks. An arrest has been made. Law enforcement sources say the suspect is Paul Kevin Curtis from Tupelo, Miss.
An envelope addressed to Sen. Roger Wicker of Mississippi twice tested positive Tuesday for ricin, a potentially fatal poison, congressional officials said, heightening concerns about terrorism a day after a bombing killed three and left more than 170 injured at the Boston Marathon.
The Army says it’s starting clinical trials at Fort Detrick on a potential ricin vaccine.