Texas officials Monday arrested a man responsible for sending at least 500 hoax letters with white powder.

Hong Ming Truong, a 66-year-old resident of Rowlett, was charged with false information and hoaxes, a criminal complaint stated. He appeared in the federal court at the Northern District of Texas for sending what "may have reasonably been believed" to be anthrax since 2008, the complaint stated, reports Reuters. The alleged letters, sent in May 2012, began with "Al Qaeda back!" and that the sender was with the militant Islamist organization.

The terror threat letters were allegedly sent to schools, government offices, day care centers and U.S. embassies around the world, the authorities said. Recently, hotels near the stadium where this year's Super Bowl in New Jersey was conducted received similar letters.

Upon investigation authorities said the white powder believed to be anthrax was harmless.

"We believe Hong Minh Truong is responsible for the hundreds of letters sent to locations worldwide, including U.S. government offices, aerospace companies, schools, daycares, and recently, hotels in the vicinity of Super Bowl XLVIII," said Dallas FBI special agent in charge Diego Rodriguez in a written statement, reports USA Today.

As per the court documents, FBI and the U.S. Postal Inspectors spent several months sifting through trash outside Truong's home on Rosebud Drive in Rowlett and found the evidence. Officials said one document recovered this month contained alleged threats, including, "Hijack airplane from Love Field airport and Dallas-Fort-worth airport to attack Nasa Center," according to WFAA.com.

Truong is due for a detention hearing August 4. If convicted he might land up in jail for up to five years with a $250,000 fine.