On July 10, 1941, in Jedwabne, a town of roughly 3,000 inhabitants in northeastern Poland, a mob of Catholics murdered most of their Jewish neighbors. Estimates of the number of victims vary, from about 300 men, women and children to as many as 1,600. Whatever the correct figure, very few Jews survived. Using axes, clubs and knives, the mob first killed some 40 Jewish men. The remaining Jews — men, women and children, many of them infants — were herded into a wooden barn on the outskirts of the town. Then, as the jeering crowd watched, the murderers barred the doors, poured gasoline on the structure and lit the fire. Everyone inside died. Plunder of Jewish homes followed. Peasants from neighboring villages, who had begun arriving in Jedwabne at dawn on the day of the massacre, joined in the fun.

The Polish journalist Anna Bikont’s beautifully written, devastating and very important book, “The Crime and the Silence” (published in Poland in 2004, and now expertly translated by Alissa Valles), details her painstaking reconstruction of this crime, along with the attempt by families and descendants of the perpetrators, right-wing politicians, historians, journalists and Catholic clergymen to cover it up and deflect blame on the victims.

Both the crime and the fact that the perpetrators were Catholic Poles entered the public record at the latest in 1949, when 21 Jedwabne men and one German gendarme were tried for the murders before the district court in Lomza, the seat of the district government. Eleven Polish defendants and the policeman were found guilty; the others were acquitted. The press reported the proceedings, but the coverage doesn’t seem to have created a stir. Sensibilities had been dulled by World War II, when Germans slaughtered some three million Polish Jews and more than two million Polish Catholics. A few years later a monument was erected near the barn where Jews were immolated, but the inscription read: “The site of the martyrdom of the Jewish population. Gestapo and Hitler’s gendarmerie burned alive 1,600 people, July 10, 1941.” The Catholic Poles who had done the killing could rest easy.

So matters stood until 2000, when a ­Polish-born American academic, Jan T. Gross, published in Poland a Polish-­language book that told the real story of the massacre. The following year it was issued in the United States, in English, as “Neighbors: The Destruction of the Jewish Community in Jedwabne, Poland.” According to Anna Bikont, the relative quiet that reigned after the publication of Gross’s book in Polish turned into a media storm once the realization sank in that “Neighbors” would expose to the American public an incident shockingly at odds with the image Poles presented of themselves as a martyred but heroic and noble people. “Neighbors” was attacked as libelous and inadequately documented, and as part of a Jewish effort to extract compensation for the lives taken during the Jedwabne pogrom. There was an orgy of denials of responsibility, including claims that the killing had been done by German SS and gendarmes — because if it had been just Poles (the reasoning went), the Jews would have resisted. Another argument said the victims were killed not because they were Jews but because they had collaborated with the Soviet occupation. (Jedwabne was part of the Polish territory assigned to the Soviet Union by the Molotov-Ribbentrop pact, breached by Germany in June 1941.) The fact that infants were among the victims was callously ignored.

Gross claimed 1,600 Jews had been killed. Except with respect to that number, his version of the events in Jedwabne has been fully vindicated. In September 2000, the Institute of National Remembrance (I.P.N.), an entity established by the Polish Parliament, began investigating the massacre. Three years later it announced the case had been closed because no living perpetrators could be identified. However, its examination of the case, including a review of the 1949 judicial proceedings and a new investigation by the special prosecutor, had led to the conclusion that while the crime was inspired by Germans, “insofar as the participation of the Polish population in the execution of the crime is concerned, it is necessary to accept that it played the determinative role in the execution of the criminal plan. . . . The perpetrators of these crimes, as the executors sensu stricto, were the Polish inhabitants of Jedwabne and the surrounding area.” Finally, on July 10, 2004, the spokesman of the Polish Press Agency declared that no appeals had been filed challenging the investigation’s ­conclusions.

One hopes — without much confidence — that those who complained about Gross’s book being inadequately documented blushed with shame when they came face to face with Bikont’s impeccable research. She reports on innumerable interviews with men and women of Jedwabne, some of whom participated in the pogrom and many of whom were old enough at the time to remember gruesome details. Her text includes a journal she kept during her investigation, so we follow her kilometer by kilometer as she zips along country roads, often iced over, in the remote Lomza district. We are at her side when she knocks on doors, most often promptly slammed in her face, behind which she knows lurk the perpetrators or their survivors or witnesses who will be too afraid of their neighbors to speak to her. We hear the insults flung at her, which grow more vicious as it becomes known that she is half Jewish, and the surreal conversations she holds with the three brothers whose participation in the crime is on record, and with the parish priest, a Jew-baiting anti-Semite who orchestrates the village population’s rejection of responsibility for the crime. There are other interviews, bittersweet, in Israel, in Brooklyn, in Costa Rica, with survivors or families of survivors who left crucial memoirs that have enabled Bikont to flesh out her ­narrative.

Two terrifying forces emerge as motivating the Jedwabne pogrom: viral anti-Semitism inculcated in the population since the 1930s by the nationalist right and nourished to this day by a segment of the Polish Catholic Church, combining with insatiable greed, the irresistible need to get hold of Jewish property and hold on to it. The number of anti-Semites, Bikont reports, quoting a sociologist who has studied anti-Semitic attitudes, increased significantly after the “Jedwabne affair flared up. . . . Why? Jedwabne has sharpened our sense of competitive suffering.” The son of a survivor asks her: “How can a Jew live in Poland?” Bikont reports that she tried to explain, probably not very well. One could suggest some imperfect responses. Among them, love of the Polish language and culture, a job or a career one likes, a spouse or a life partner committed to living in Poland, the lack of a good alternative and, above all, fear of the unknown.

The gloom and pessimism, the sense of physical disgust at the vile depth of Polish anti-Semitism and denial, which would otherwise engulf one as one reads Bikont’s book — and would surely have engulfed her — is relieved only by the presence in her pages of certain morally splendid and heroic Poles: Antonina Wyrzykowska, a simple peasant woman who with her husband saved seven Jedwabne Jews and kept them in safety until the end of the war; Stanislaw Ramotowski, another peasant from near Jedwabne who hid a Jewish schoolmate, married her, and was an invaluable guide for Bikont; Krzysztof Godlewski, the intrepid mayor of Jedwabne who stood up for installing a new and more honorable memorial for the victims; Jan Skrodzki, who indefatigably helped Bikont to track the murderers, among whom was his own father; and Radoslaw Ignatiew, the quiet special prosecutor whose investigation of the Jedwabne massacre laid the basis for I.P.N.’s conclusion that the perpetrators had indeed been the Polish Catholic neighbors of the slaughtered Jews.