FBI Reveals Another Round of Suspicious Letters to Obama, CIA As federal authorities question a person of interest in the mailing of possibly poison-laced letters to New York Mayor Michael Bloomberg and President Obama, the FBI revealed late Thursday that they arrested a Washington man for allegedly sending his own group of suspicious letters to five targets including the President, an Air Force base and to the CIA. According to an FBI statement, the bureau arrested 38-year-old Matthew Buquet of Spokane last week after authorities intercepted a letter to a Spokane federal judge that later tested positive for the ricin toxin. He was charged with a single count for allegedly mailing threatening communications, but the FBI said four other "similar" letters were sent around the same time to a Spokane post office, the White House, a Washington Air Force base and to the CIA. The revelation came as authorities said they identified a person of interest in New Boston, Texas in the case of another series of possibly ricin-laced letters, bearing a threatening anti-gun control message, sent to Mayor Bloomberg and Obama. A law enforcement source said the man's wife called authorities after she noticed strange material in her refrigerator and saw computer searches for ricin. New Boston is located about an hour and a half drive from Shreveport, La., where the Bloomberg and Obama letters were postmarked. No arrests have been made in that case, the FBI said. In both the Bloomberg case and the Spokane case, the letters did not reach their intended targets and in the Bloomberg case, the U.S. Postal Service said Thursday that the letters were not a health threat. Ricin can be dangerous, even fatal, but only if delivered in a very intense dose. There has been no indication that the Bloomberg and Spokane cases are related. Images of one of the letters sent to Bloomberg, obtained by ABC News, show globs of a pinkish, tan substance splattered on a typed letter. "You will have to kill me and my family before you get my guns," the letter reads. Two law enforcement sources told ABC News Thursday that the Bloomberg letters appeared to be the work of an "amateur" because the toxicity levels were so low. "It may not have been correctly made," one of the sources said. Clearly amateur hour. This is not the national threat as some are making it out to be. In the last dozen years, the U.S. mail has been flooded with some 54,000 threatening letters with unknown substances, almost half of them hoaxes. This year there have been at least six letters sent to public figures confirmed by the FBI as containing ricin. ABC News' Aaron Katersky contributed to this report.