New York City Mayor Eric Adams said Monday that the 21-year-old man arrested at Penn Station over the weekend was not making idle threats about attacking a New York City synagogue.
Christopher Brown, from the town of Aquebogue on Long Island, told investigators he has a "sick personality" and tweeted that he was going to ask a priest "if I should become a husband or shoot up a synagogue and die," according to the criminal complaint.
Police recovered a Glock semi-automatic firearm with an extended 30-round magazine and laser sight, a large hunting knife, a black ski mask and a Nazi armband, prosecutors said.
"This was not an idle threat," Adams said. "This was a real threat."
The NYPD, the New York State Police and departments on Long Island have increased security at synagogues and other Jewish institutions as a result of the threats and Adams said the extra protection for the city's 1.6 million Jews would continue through Hanukkah.
"We're always concerned about copycats," Adams said. "No one should ever feel threatened walking into their synagogue or place of worship."
Brown and another man, Matthew Mahrer, 22, were arrested Friday night after Metropolitan Transportation Authority police officers spotted them entering Penn Station following a notice from the Joint Terrorism Task Force.
"They had full descriptions from the other law enforcement," MTA chief Janno Lieber said.
Brown was said to have posed a threat to an unidentified synagogue, according to the FBI. Mahrer was subsequently identified as an associate.
"We have no information there is any continued threat to the Jewish community in connection with this case," said the FBI's Michael Driscoll.
Brown and Mahrer have not yet entered a plea to state charges. Federal prosecutors are still deciding whether additional charges are appropriate.