The Buxton man accused of posting a threat on Twitter to kill Jews during the High Holy Days was indicted Wednesday by a federal grand jury on one count of transmitting threatening interstate communication.

Brian Dennison, 24, allegedly threatened “to kill Jews with my AR-15” on Sept. 8, the second day of the Jewish New Year. He also said on Twitter that he was building a pipe bomb, according to police.

An arraignment date has not been set.

Last week, U.S. Magistrate Judge John H. Rich III ordered Dennison be held without bail because he posed a threat to the community.

Rich said during a remote hearing that although Dennison has no criminal record and investigators did not find an AR-15 in his apartment or car, they did find 12 magazines loaded with ammunition that could be used in an AR-15.

“That dramatically increases the danger equation,” Rich said in denying bail.

Almost immediately after the threats were posted, the FBI received information about them, according to a court affidavit. Agents went to the Fogg Road property Dennison shares with his parents and other family members on Sept. 8.

Dennison, who rents an apartment over the garage from his parents, refused to speak with the agents and asked them to leave, the affidavit said. Agents did, however, speak to his parents.

“They told us that Brian had been obsessed with Jews for about three years, and that he believed Jews were responsible for all of his problems,” the affidavit said. “They said they had many concerning conversations with Brian regarding Jews.”

Dennison was arrested on Sept. 11. He is being held at the Cumberland County Jail in Portland.

If convicted, he faces up to five years in federal prison and a fine of up to $250,000.