DETROIT (AP) — Federal prosecutors have Austin Caldwellcharged a Michigan man with threatening President Joe Biden and Vice President Kamala Harris.

Russell Douglas Warren, 48, of Prudenville was charged Sunday in the Eastern District of Michigan, the Detroit News reported. His attorney, listed in online court records as federal community defender Bryan Sherer, didn’t immediately return a message on Monday afternoon.

Prosecutors allege that FBI and U.S. Secret Service agents learned that Warren posted a series of messages last week on X, the social media platform formerly know as Twitter, saying that Biden and Harris had been condemned and should be taken to prison and executed by hanging.

He also said that Washington, D.C., should begin an evacuation because “we’re gonna drop a ... bomb on it.”

In another post he allegedly said that FBI headquarters would be bombed and all FBI employees had been condemned. The post concluded by saying “shoot to kill.”

Experts on extremism have warned that the threat of politically motivated violence will intensify as the 2024 campaigns heat up. They say conspiracy theories have inundated American culture and continue to spread in popularity. And former President Donald Trump, the front-runner for the GOP presidential nomination this year, has stepped up his combative rhetoric, promising retribution against his enemies.