A North Texas man was arrested and charged Monday for sending more than 500 hoax letters, containing a white powder and warnings of terrorist attacks, to U.S. government offices, companies, schools and hotels, according to federal authorities.

The 66-year-old man, identified as Hong Minh Truong, reportedly began sending the letters in 2008 and though the powder inside eventually proved to be harmless, it was initially presumed to be poisonous and “each incident required a field screening of the letter’s contents, which cost taxpayer dollars and diverted first responder resources.” Truong has reportedly been ordered to remain in federal custody until a detention hearing scheduled for August 4. If convicted, he could face up to five years in prison and a fine of $250,000.

“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,” Diego Rodriguez, special agent in charge of the FBI’s Dallas office, reportedly said, in a statement. “For almost six years, letters containing white powder -- and believed to have been mailed by the same individual -- have elicited law enforcement and public safety responses from numerous local, state and federal agencies.”

According to a complaint filed against Truong, the letters had been sent “from the North Texas areas to cities across the United States and to United States Embassies abroad.”

According to Fox News, one letter stated that the sender would "Hijack airplane from [Dallas's] Love Field airport ... to hit NASA center or Empire [State] Building."

In a May 2012 incident, letters mailed from Dallas contained the words:

Al Qaeda back! Special thing for you... What the hell where are you, Scooby Doo, Counter Intelligence, CIA, you... do not know how to catch the triple dealer spy in your law enforcement... 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... You all flaming idiot, ignorant and arrogant, know nothing! How to protect... this country! U.S.A... We are Al Qaeda, U.B.L FBI, Al Qaeda, SS Nazi FBI, working in your... agency. We claim everything.

These letters were sent to schools across the country, forcing Hazmat teams, which include specially-trained personnel to handle dangerous goods, to respond to all the sites.

An investigation, after similar letters were sent to 28 public schools in Boston in June 2013, reportedly led to the identification of an IP address in Rowlett, Texas, linked to Truong, and eventually led to his arrest, reports said.