The 23 swastikas scrawled in Brooklyn Heights last week and the anti-Semitic leaflets scattered around the neighborhood comprise one of the more atrocious acts of vandalism the commander of the New York City police hate crimes task force says he has seen.

The vandals succeeded in marking up two synagogues and private homes despite stepped up security during the Jewish high holidays, including increased citywide surveillance by counterterrorism Hercules squads wielding submachine guns and bomb-sniffing dogs.

Then, there was a repeat incident: A synagogue in Bensonhurst was marked up with swastikas just a few days later.

Deputy Inspector Michael Osgood, who has led more than 1,500 bias crime cases during his career, had comforting words for religious communities shaken by the incidents, which police believe are unrelated. The vandals were probably acting alone, and probably won’t strike again, he said in an interview yesterday.

“Even though this act is very egregious, there’s no evidence that anything worse will occur,” he said. “The hate crime offender in New York is someone who does it once, and who doesn’t really repeat.”

He also noted that while hate crimes are up slightly this year in the city, they’re down 60% from 15 years ago.

The New York City Jewish community, after a strong condemnation of the incident, seems to be heeding Mr. Osgood. Leaders at synagogues around the city said yesterday that they and their congregations are responding to the Brooklyn incidents with relative calm, suggesting, perhaps, that the vandals’ attempt to strike fear in the Jewish community fell flat.

“We’re moving on. They’re not going to win, they’re not going to hurt us as much as they would like,” the rabbi of the Sons of Israel Synagogue in Bensonhurst, Baruch Krupnik, said.

At that synagogue, one of the borough’s oldest, an elderly Holocaust survivor was the first to discover three swastikas drawn on the temple walls on Friday night.

Mr. Krupnik said the synagogue considered adding extra security measures to protect the building, but likely won’t.

“We’ll just rely on the police, and we have locks on the door,” he said. “It’s very difficult prevent.”

A strong response to bias attacks is the best prevention, Mr. Osgood said.

The City Council announced yesterday that it is going to hold a hearing next month on a new bill proposed by Council Member Peter Vallone Jr. of Queens that would set a minimum fine of $10,000 for hate crimes involving property damage.

The hate crimes task force has thrown its full weight into the investigation of the Brooklyn Heights incident, adding 20 extra investigators to the case and sending police officers and sanitation workers to root through the trash and sewers in search of clues.

Still, it’s unclear at this point if the perpetrators will be caught, Mr. Osgood said, and the police department currently has no leads.

“They’ve got their work cut out for them,” the rabbi of the Union Temple in Park Slope, Linda Henry Goodman, said. “I think it’s important for the community just to express zero tolerance — nobody wants that sort of thing to happen to them where they live or where they pray.”