Matthew Mahrer as a boy wrote a 25-page book about his grandfather’s experiences as a prisoner in a Nazi internment camp.

Christopher Brown did favors for the Orthodox rabbi across the street, who needed someone to turn on electrical devices during the Sabbath or Jewish holidays.

In November 2022, they were both in free fall. Christopher Brown, then 21, posted on Twitter that he wanted to “shoot up a synagogue and die.”

Matthew Mahrer helped him get the gun.

They were drunk or high, heading into New York City with a Glock 9-millimeter pistol, an extended magazine and 19 bullets. When they were arrested in Pennsylvania Station that night, it rattled a Jewish community that was still on edge from the massacre of 11 people at a Pittsburgh synagogue four years earlier.

Their arrest was a chilling story — an “antisemitic sicko” bent on mass murder — made more sensational by the revelation that his accomplice was Jewish.

“There were 19 bullets in that ammo clip,” said Glenn Richter, who attended a synagogue near the Mahrers. “Had they decided to go around the corner and go into the synagogue, I and others could have been among those 19 casualties.”