US charges Mississippi man over ricin threat

Suspect charged with threatening to harm president Obama and making other threats through Postal Service

Federal prosecutors have filed criminal charges against Paul Kevin Curtis, the Mississippi man who was arrested a day earlier in the FBI's investigation of letters believed to have contained the deadly poison ricin.

A criminal complaint filed in US District Court for the Northern District of Mississippi charges Curtis with threatening to harm president Barack Obama and making other threats through the Postal Service.

Mr Curtis, who is scheduled to be brought before a magistrate today in Oxford,

Mississippi, could face as long as 15 years in prison if convicted. A letter to Senator Roger Wicker, a Mississippi Republican, initially tested positive for the toxic substance at a congressional mail facility in Washington on Tuesday, the day after three people were killed and more than 170 injured in a bombing at the finish line of the Boston Marathon.

The letter to Mr Obama was identified yesterday at a mail facility separate from the one that sorts congressional mail. It was quarantined after an initial test indicated it contained ricin, Secret Service spokesman Ed Donovan said in an e-mail. The sample will require more tests to confirm the results.

There was no effect on White House operations, the FBI said. Mixed Results While preliminary test results were positive for ricin, they also showed mixed results. Field tests can at times be unreliable, so federal officials sent the envelopes to an accredited lab for further testing. The letters' discovery following the Boston bombings evoked memories in Washington of anthrax mailings that targeted politicians in 2001.

Shortly after that year's September 11th attacks, letters containing anthrax were sent to two senators during a series of mailings to media and government offices that claimed five lives across the US.

No lawmakers were harmed. The letters and the Boston bombings haven't been linked. Ricin is a poison made from castor beans, according to the Centers for Disease Control and Prevention in Atlanta. It's harmful and potentially fatal if inhaled or ingested, and isn't contagious, the CDC said on its website. Symptoms depend on the purity, route of exposure and the dose. Initial symptoms from inhalation occur as early as four to six hours after the exposure, and symptoms include difficulty breathing and a cough, according to the CDC. The symptoms can progress rapidly to fluid within the lungs and eventually respiratory failure. Deaths from the poison usually happen within 36 to 72 hours. While no antidote exists, doctors can counteract the effects of the poisoning by helping victims breathe or giving them fluids