Federal prosecutors have indicted a Michigan man for allegedly sending an email threat to attorney Mark Zaid, who represented the intelligence community whistleblower at the heart of the impeachment inquiry against President Donald Trump.

According to an indictment unsealed this morning in the Eastern District of Michigan, Brittan Atkinson on Nov. 7 sent an email to Zaid reading, "All traitors must die miserable deaths. Those that represent traitors shall meet the same fate."

Zaid confirmed to ABC News Thursday that he received the email and said he only Thursday learned of the indictment against Atkinson. The indictment was first reported by Seamus Hughes, the Deputy Director of the Program on Extremism at George Washington University

According to the court docket, Atkinson has pleaded not guilty to the charge of sending threatening communications and a judge ordered he will remain detained through his next hearing on Feb. 24.

Prosecutors allege Atkinson also wrote in his email to Zaid, "Keep looking over your shoulder. We know who you are, where you live, and who you associate with. We are all strangers in a crowd to you."

Just Wednesday, a Western New York man was arrested on charges that he threatened to kill Rep. Adam Schiff, D-Calif., and Sen. Chuck Schumer, D-N.Y. When questioned by U.S. Capitol Police, Salvatore Lippa allegedly said that he made the threatening calls to Schiff's and Schumer's offices because he was upset about the impeachment proceedings.

Lippa was to appear in federal court in Rochester on Wednesday afternoon. He faces up to 10 years in prison.

"It's not appropriate for anyone to threaten another individual's life, regardless of political views. My job was to ensure the rule of law was followed in how whistleblowers are treated. That role should not be negatively weaponized by partisans. I hope this indictment sends a message to others that such behavior will not be tolerated by a civil society that is governed by law," Zaid said.