The Department of Justice is investigating dozens of threats made to election workers, federal officials said Monday, and has charged 20 individuals so far.

“These are the first responders of democracy and we will continue to investigate and prosecute those who would threaten to do them harm,” said Gary Restaino, U.S. Attorney for the District of Arizona, at a press conference highlighting the recent convictions.

Thirteen of the 20 charged individuals have been convicted. Of the ten who have been sentenced already, seven have received prison sentences of more than 18 months, “signaling how serious federal courts are taking this conduct,” said John Keller, a DOJ official who leads day-to-day operations of the agency’s Election Threats Task Force.

“This new era in which the election community is scapegoated, targeted, and attacked, is unconscionable and in addition to the obvious toll taken on individual victims, risks depleting the ranks of experienced election officials vital to the effective administration of our elections,” said Keller, whose task force helps local officials proactively search for, investigate and prosecute threats to election workers.

Two of the convicted individuals were sentenced in March for making threats against former Arizona Secretary of State Katie Hobbs, a Democrat who is now the state’s governor.

Joshua Russell, an Ohio man, was sentenced Monday to 2.5 years in prison for leaving threatening voicemails with Hobbs office.

According to federal authorities, Russell said in a 2022 voicemail to Hobbs that “you have a few short months to see yourself behind bars, or we will see you to the grave. You are a traitor to this nation, and you will suffer the [expletive] consequences.”

James Clark, a Massachusetts man, was convicted for making a bomb threat against Hobbs in 2021 that triggered a partial evacuation. Clark later conducted online searches about the Boston Marathon bombing, Restaino said. He was sentenced earlier this month to 42 months in prison.

Arizona was the epicenter of the stolen election claims in 2020, which were fueled by Donald Trump’s narrow loss in the state. Trump has claimed for years he won the election, though dozens of lawsuits, investigations, and reviews have found no evidence supporting his claim.

Most threats reviewed by the FBI are not criminally actionable, officials said Monday, though they noted that every single reported communication is reviewed. To reach the level of a crime, Restaino said, a communication must include a “serious expression that a speaker means to commit an act of violence.”