(CNN) — A grand jury indicted two men — one of whom is Jewish and a descendant of a Holocaust survivor — in connection with an online threat last month to attack a synagogue in New York City.

Christopher Brown and Matthew Mahrer were both indicted on charges of conspiracy and weapons possession. Brown also was charged with a felony count of making terroristic threats as a hate crime, and possession of a weapon as a crime of terrorism, among other charges.

Mahrer, who previously made bail, appeared on Wednesday in Supreme Court in New York, with family members present. He is Jewish and his grandfather is a Holocaust survivor, defense attorney Brandon Freycinet said in court, adding that his client would not want to harm his own people.

Both defendants pleaded not guilty to the charges on Wednesday.

Brown and Mahrer were arrested by officers from the Metropolitan Transportation Authority as they were entering Penn Station in Manhattan on November 19, according to NYPD Commissioner Keechant Sewell.

The suspects allegedly possessed a firearm, high-capacity magazine, a military-style hunting knife, a Nazi swastika arm patch, a ski mask and a bulletproof vest, officials said.

“A potential tragedy was averted when they were intercepted by police officers at Penn Station, given that online postings indicated an intent to use these weapons at a Manhattan synagogue,” Manhattan District Attorney Alvin Bragg said last month in a statement.

Law enforcement sources previously told CNN the threats began appearing on a Twitter account on November 12 and were traced to a computer at a veterinary clinic where one of the suspects worked. Law enforcement put out a BOLO alert — “Be on the lookout” — for the suspects, and two sharp-eyed MTA officers stopped and arrested them.

Investigators identified an address on the Upper West Side associated with a suspect’s friend and learned the two men had dropped off a backpack there, sources said. The backpack contained a Glock semi-automatic firearm, a ghost gun with an extended 30-round magazine and laser sight, the sources added.

New York state leads the nation in antisemitic incidents, with at least 416 reported in 2021, including at least 51 assaults — the highest number ever recorded by the Anti-Defamation League in New York. There were 12 assaults reported in 2020, the ADL said in an audit last week.

A total of 2,717 antisemitic incidents were reported last year across the nation — a 34% increase compared to 2,026 in 2020, according to the ADL.

The ADL has been tracking such incidents since 1979 — and its previous reports have found antisemitism in America has been on the rise for years.

(Copyright (c) 2024 CNN. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

Join our Newsletter for the latest news right to your inbox