When Mireille Knoll was about 7 years old, she escaped a roundup of French Jews in Paris; those Jews who did not escape, including her family, soon were slaughtered by the Nazis and their eager allies.

We are told that one of the two young men who the French police arrested for her brutal murder — “brutal” might be a tabloid word, but it is hard to know what more gentle word could be applied to a death that involved being stabbed 11 times and set on fire — knew Ms. Knoll since he was 7; she was kind to him, we are told. She was a kind woman, we are told, as well as chic in the Parisian way that elderly women can maintain with such apparent ease in that capital of chic.

She was 85 years old, and in failing health, when she was killed on March 23.

But she was Jewish, and apparently that was enough to provoke her murderers, according to French officials.

It also apparently was enough to provoke an anti-Semitic murderer to kill Sarah Halimi, a 66-year-old retired physician and kindergarten teacher who lived a few blocks away from Ms. Knoll, in 2017. Ms. Halimi was beaten and then thrown off her balcony, apparently by a young man who lived in the apartment beneath hers in Paris’s gentrifying 11th Arrondissement.

It is easy to draw parallels between now and World War II that are more sweeping than they should be. Jews were murdered wholesale by government decree then; now these murders are more retail, individual, by killers who apparently are psychotic. (There is much room for study on the differences between people made into murderers by the surrounding culture that encourages it, and people who are psychotic because their brains are wired badly.)

And the reaction to the deaths have been different.

Despite some initial reluctance to label them, as well as other similar murders of Jews, as anti-Semitic (and with a very real need to make sure of the truth of that claim before making it), the French government has acknowledged the problem and denounced it. French politicians showed up at Ms. Knoll’s funeral, and at a memorial march and vigil that followed. There has been a great deal of outrage at the murder and the anti-Semitism that seems to lie behind it in France, and its politicians are reacting.

The Jewish community turned out in force, and some Jews from outside France took action as well. Rabbi Avram Mlotek was among them.

Rabbi Mlotek grew up in Teaneck — his parents, Debra and Zalmen, the artistic director of the National Yiddish Theatre — Folksbiene, still live there — and now is the rabbi of the downtown New York’s Base Hillel (he and his wife, Yael Kornfeld, co-founded the growing millennial Jewish group). He is strongly motivated by the need for justice, and the competing pulls of history and the future. “I heard about the brutal murder, and I just felt called to go there,” he said, in a phone call from the airport in Paris last Thursday, the day before Pesach started, as he waited for his flight home.

“I had been in New York, I had just come from a beit din where we had squeezed in two conversions,” Rabbi Mlotek said. “And I thought of my grandmother, who is Ms. Knoll’s age, a Holocaust refugee from Germany who is living in Connecticut, my mother’s mother, Miriam Wolkenfeld Cohen, and I realized that I had to go.

“I called my rabbi, Avi Weiss, who usually goes on missions like this, but he and the other rabbis who usually would do it couldn’t, because it was so close to Pesach. But they were all supportive of me, and Rabbi Weiss connected me to the head of the chevra kadisha,” the burial society, “there.

Rabbi Avram Mlotek

“My wife and I had just spent seven hours cleaning, and we were going to welcome more than 50 young Jews to our home for the seder, but I hopped on a plane.” No worries — he got back home in time to cook and prepare.

“But I met with the organizers of the rally, and I went to the funeral, and it was just so powerful.”

The president of France, Emanuel Macron, was at the funeral. So too were somewhere between 100 and 200 mourners, Rabbi Mlotek reported. “I introduced myself to the officiating rabbi and the family after the ceremony,” he said. “She was a widow and had two sons — I think her husband had been a survivor as well. Both the sons are married, and one has a daughter who made aliyah; one of the sons and that granddaughter spoke.

“I met Macron, and I met the ambassador from Israel,” he continued. The funeral was at graveside, “and it was raining, so we were all stuffed together under the tent. Right after the ceremony it poured even more rain, so we were all pushed together even closer.” Somehow, Rabbi Mlotek ended up as one of the pallbearers.

“It was unfathomable to me,” he said. “This woman, who was 85 years old, had escaped the Nazis 76 years ago, only to be murdered in her own home.

“We lined up and lowered the aron” — the casket — “into the grave. It was so powerful, the chesed shel emet,” the obligation to take care of the dead with tenderness and respect, an obligation that by its nature can never be repaid, at least by its recipient. “And there were these people, the president of France, Israel’s ambassador to France, all the mourners, standing in the mud and the rain, because before death everyone is equal.”

Because the Jewish world is so connected, Rabbi Mlotek was able to meet with other Jews through the inevitable although often improbable networks that link just about everyone. “I met with a local rabbi in Paris,” he said. “It was crazy.” He had led a group from Base Hillel to the Women’s March that filled Manhattan on the Shabbat in January 2016 that immediately followed Donald Trump’s inauguration, and on that unseasonably warm, oddly hope-filled, day, he ran into a young French Jewish woman who was looking for community. She found it at Base — “she’s coming to us for seder,” Rabbi Mlotek said — and in return she connected her mother, still in Paris, with Rabbi Mlotek, and Rabbi Mlotek got to meet her rabbi, Tom Cohen of Kehilat Gesher in Paris, an American expatriate who is “married to the first woman rabbi in France,” Pauline Bebe.

Talking to Rabbi Cohen, Rabbi Mlotek “heard about the vibrant Jewish life in Paris, juxtaposed with these horrific attacks.” There has been “a decrease in the number of anti-Semitic attacks in France, but those attacks have become more violent,” he said.

The march and the vigil that followed attracted many non-Jews, Rabbi Mlotek said; still, “there must have been 10,000 people there, and the core was Jewish students. It was driven by these youths, who want a different reality, a different France, a different home.”

It also is important to remember the reality that Passover is not only an “opportunity for the Jewish people to remember the Exodus, and to ponder what freedom means, but it is also the commemoration of the Warsaw Ghetto Uprising. I think about how my children won’t know what a Holocaust survivor’s voice sounds like by the time they grow up.

“Yes, we can talk about how genocide continues to be perpetrated, and we can chant ‘never again,’ but now there still are survivors living. It is a sacred responsibility to ensure that they can live in peace during their last years on this earth.

“The parallel to Passover is almost overwhelming. We say that in every generation they rise up against us to annihilate us. This is nothing new. There are pharaohs and there is Hitler. They have much in common. Anti-Semitism is a plague like any other plague, like racism or misogyny or homophobia. It is our responsibility to combat anti-Semitism by raising awareness and holding the bigot accountable, and it is also our responsibility to try to build a world of compassion and love.

“It is that responsibility that brought me to Paris.”