Doctors say the toxin allegedly used in letters sent to President Obama and other lawmakers in Washington can kill a person within three days.

Medical professionals say ricin is readily available because it is found in castor beans and is part of the waste produced by making castor oil. CDC officials say if the poison is refined properly, it can be deadly and can kill within 72 hours.

A powdery substance believed to be ricin was fouind on letters sent to the White House and Mississippi Senator Roger Wicker.