A federal grand jury in Atlanta indicted an Alabama man Monday on charges that he threatened Fulton County District Attorney Fani Willis over her prosecution of former President Donald Trump.

Arthur Ray Hanson was charged with transmitting interstate threats to injure Willis and Fulton County Sheriff Patrick Labat, who controls the jail where Trump was fingerprinted and photographed after he was indicted in August on charges of trying to overturn the results of the 2020 presidential election in Georgia.

Hanson made an initial appearance in Huntsville federal court in Alabama, and will be brought to Atlanta for an arraignment next month.

Hanson, 59, called the Fulton County customer service line twice in August and left two voicemail messages threatening violence against Willis and Labat, according to court records.

"Watch it when you're going to the car at night, when you're going into your house, watch everywhere that you're going," court records quoted Hanson as saying in the message left for Willis.

"I would be very afraid if I were you because you can't be around people all the time that are going to protect you; there's going to be moments when you're going to be vulnerable," the message said, according to court records. "When you charge Trump on that fourth indictment, anytime you're alone, be looking over your shoulder."

"Sending interstate threats to physically harm prosecutors and law enforcement officers is a vile act intended to interfere with the administration of justice and intimidate individuals who accept a solemn duty to protect and safeguard the rights of citizens," said U.S. Attorney Ryan Buchanan. "When someone threatens to harm public servants for doing their jobs to enforce our criminal laws, it potentially weakens the very foundation of our society."

Trump and 18 others pleaded not guilty in August to all charges in a sweeping racketeering indictment for alleged efforts to overturn Georgia's election results. Four defendants have subsequently taken plea deals in exchange for agreeing to testify against others in the case.

The former president has blasted the district attorney's investigation as being politically motivated.