The FBI and U.S. postal inspectors announced a $150,000 reward on Wednesday for information about the person who has mailed at least 380 white powder letters to schools, churches and businesses in North Texas and around the world since 2008.
All the typewritten letters have been postmarked from North Texas and have included vague messages about the FBI, CIA, al-Qaida and Nazis. Some of the most recent letters have even included references to the cartoon character Scooby Doo, agents said.
"Those who know or have encountered this person may consider him odd or eccentric," said Kevin Kolbye, acting special agent in charge of the FBI's Dallas office.
At a news conference, agents revealed details about the letters, which have been sent in 13 batches, they said.
"We need to find this person before he sends his next batch," Kolbye said. "This person is disrupting people's lives."
FBI experts believe the suspect is at least 30 years old, may have a history of mental challenges and likely does not have a mastery of the English language.
Some of the letters have included punctuation or spelling errors.
In some of the letters, the mailer wrote, "Al Qaeda back! Special thing for you."
In others, he wrote, "What the hell where are you, Scooby Doo , Internal Affairs, FBI, you don't know how to arrest the bad cop in your law enforcement."
In yet another, he wrote, "You all flaming idiot, ignorant and arrogant, know nothing! How to protect this country! U.S.A"
He also wrote about a "triple dealer spy in your law enforcement."
Agents believe the person has a gripe with the government and does not have any actual affiliation with Al Qaeda, Kolbye said.
The sender appears to taunt federal agents. In some cases, the return address on the envelopes has been current or former FBI offices. More recently, some of the return addresses are medical facilities.
Just last week, schools in Irving, Mesquite and Dallas, a Garland day care and a Grand Prairie church reported receiving white powder letters on Tuesday. A day later, firefighters responded to another call about a white powder letter at the Mi Escuelita preschool in Dallas.
On Monday, a letter containing a white powder was sent to Baylor Regional Medical Center Grapevine to the attention of a doctor who was no longer on staff.
In all of the cases, the powder was determined to be harmless.
Letters containing powder invoke fear after five people were killed and more than a dozen were injured when letters laced with anthrax spores were mailed to offices in the days and weeks after Sept. 11, 2001.
Since then, hundreds of hoax letters have been received nationwide at schools, banks and other businesses. Though they've been harmless, anyone receiving a white powder letter is advised to evacuate the area and call 911.
The letters have been sent to every state except Ohio and Kentucky and to embassies and consulates in numerous foreign countries, agents said.
Finding the mailer has been a challenge.
He has made sure not to leave fingerprints or other clues on the envelopes, agents said.
The letters were all postmarked from the postal processing center in Coppell, but that facility handles mail from 1,600 individual mailboxes scattered across much of North Texas.
"Someone knows who this person is and we're asking them to do the right thing," said Randall Till, inspector in charge of the postal service's Fort Worth division.
The mailings apparently started in December 2008, when the person sent white-powder letters to at least 40 governor's offices and 19 U.S. embassies overseas.
At that time, the FBI and postal inspectors announced a $100,000 reward for information about the suspect but agents have been unable to solve the case.
Former federal agent and terrorism expert A.J. Irwin said he believes the mailer will ultimately get arrested.
"I think they're going to find him," he said. "I think the person is getting a thrill out of it and whenever he needs a high, he's sending out these letters."