U.S. Attorney General for the District of Connecticut John H. Durham announced a federal grand jury has indicted a Connecticut man who allegedly threatened to kill President Donald Trump and others, according to a Department of Justice news release.

Federal prosecutors have accused Gary Joseph Gravelle of sending a letter threatening to kill the president in September. He's also accused threatening to harm others and blow up property in Connecticut via the U.S. mail, email, and telephone.

On Thursday, a federal grand jury in New Haven indicted the 51-year-old Gravelle on 16 counts that could land him in prison for up to 140 years.

Gravelle, who is also known as Roland Prejean, was identified as a member of the American Knights of Anarchy, or AKA, according to the court documents, the New Haven Register reported.

What are the details?

Gravelle allegedly mailed several letters that contained a white powder along with a piece of paper that said, "You Die" and "Anthrax is an acute infections disease caused by the spore-forming bacterium Bacillus anthracis, a category A agent," according to court documents, the newspaper reported.

In the letter to Trump, which also included a white powder, Gravelle allegedly wrote, "I, Gary Gravelle, ... as a faithful soldier of the AKA, am coming to KILLDonald Trump ... "

The powdery substance turned out to be harmless, officials said.

The suspect also allegedly made phone calls threatening to detonate explosives at several locations in New Haven, including Fellowship Place (called "Fellowship House" in the indictment), and the Continuum of Care and the Connecticut Mental Health Center, according to the Register. He made similar bomb threats against Abraham A. Ribicoff Federal Building in Hartford, Seattle-Tacoma International Airport, and Burlington International Airport, among others.

What are the charges?

The federal grand jury charged Gravelle with 12 counts of maliciously conveying false information about an explosive, which carries a maximum sentence of 10 years for each count and three counts related to sending hoax Anthrax letters, which carries a maximum sentence of five years for each count.

Gravelle also faces up five years for making threats against the president.

What else?

Authorities arrested Gravelle on Sept. 8 for violating the terms of his federal supervised release from a previous conviction.

"He was under federal supervision when he allegedly committed the offenses charged in the indictment, having been convicted and sentenced in 2013 for offenses stemming from his sending threatening communications," the release said.

Gravelle remains in custody.