Investigators say 25 white powder hoax letters mentioning al-Qaida have been received by churches, mosques and businesses in the Dallas area since Aug. 5.
A person who sent threatening letters containing suspicious white powder to several U.S. embassies and governors' offices two years ago recently sent 30 more such letters to churches, mosques and businesses in Texas, Illinois and Massachusetts, federal officials said Friday.
The most recent batch of envelopes contained a powder shown to be nontoxic and a single typewritten sentence in English that is unclear in meaning but that mentions al-Qaida, FBI Special Agent Mark White said. He declined to elaborate on the wording.
"Nobody understands what they're trying to say," White said Friday. "The message itself is unclear. But by taking that extra step and putting that white powdery substance in there, yes it's considered a threat."
Twenty-five of the letters were sent to addresses in the Dallas area, and the other five were sent to locations in Austin, Lubbock, Chicago and Waltham, Mass., according to the FBI and U.S. Postal Inspection Service. They were postmarked in northern Texas.
"The letters all have the same postmarks, the same content and similar return addresses that lead us to believe they are coming from the same person or persons," White said. Businesses receiving the letters all seem to be in the aeronautics or tech industries, he told The Associated Press.
FBI investigators believes the same person or group has sent more than 250 such letters since December 2008, including a batch sent in December 2008 to eight U.S. embassies and many governors' offices.
Authorities are offering up to $100,000 for information leading to the arrest and prosecution of those responsible.