Scott Gordon, NBCDFW.com
Federal agents are investigating whether or the letters are linked to hundreds of similar mailings since 2008.
Federal agents are investigating whether or not at least 13 letters with white powder received by North Texas businesses and religious institutions in the past two days are linked to hundreds of similar mailings since 2008.
NBC DFW reported in April that dozens of white-powder letters sent to governors, U.S. embassies and other locations all contained the same neatly typed but cryptic message: “Al Qaeda FBI in America.”
FBI spokesman Mark White in Dallas said on Friday he could not comment on details of the most recent mailings.
But one of the recipients confirmed the letter contained the same reference to the FBI and the terrorist group.
The letters were received Thursday and Friday by a church, a mosque and a number of technology or aerospace companies in Dallas, Arlington, Grand Prairie, Carrollton, Ricardson and McKinney.
The mailings appear to have started in December 2008, when someone sent letters containing white powder to at least 40 governors and 19 U.S. embassies from Spain to South Korea.
All the letters were postmarked "Dallas" or "North Texas," which indicates it was processed at the post office in Coppell, the FBI said at the time.
The meaning of the short message in the letters is hardly clear, but the sender appears to taunt the FBI. The return addresses were current or former FBI offices, agents said.
In every case, the white powder turned out to be harmless. But the scares caused evacuations, the mobilization of hazardous materials teams, and in some cases, sent people to the hospital as a precaution.
In November 2009, white powder letters with the same reference to the FBI and al-Qaida were sent to at least seven foreign missions at the United Nations in New York. Employees who came in contact with the letters had to be decontaminated.
"Anybody who thinks it's a joke is making a very bad mistake," an angry New York Mayor Michael Bloomberg said at the time.
On April 6, elementary schools in Garland and Sachse received white powder letters with the same one-line note, a school employee said. The schools were evacuated, and parents rushed to check on their children.
The same month, a letter that surfaced at an American Airlines office at Love Field appeared to be nearly identical, law enforcement officials said.
A Dallas Fire-Rescue hazardous materials team found that the white powder was harmless.
Sending threatening letters, even it it's a hoax, is punishable by up to five years in prison for each letter sent.