Murder is most often performed in secret and only partially brought to light; some portion of the “evil lurking in the hearts of men” remains forever obscured. Though public fascination for high-profile murder cases may include sordid voyeurism, it is also motivated by a need to pierce the mystery, understand the motivations, and judge fairly. Murderers show no mercy for their victims, but civilized society is horrified at the thought of convicting the innocent or letting the guilty run loose. Vendetta short-circuits the painstaking efforts to get to the truth. Or does it? Isn’t the infinite ping-pong of vendetta a sign of profound dissatisfaction with this poor excuse for justice?

Jersey City, N.J., January 14: The four members of the Armanious family are discovered in a state that no normal human being would even want to imagine, let alone see – bound and gagged, their throats slit, their faces mutilated, their blood spilled, their torment ineffaceable. The voice-of-reason respectable press, quoting police officials, reports that the most likely motives are robbery or a dispute with a former tenant. Yes, of course, anything is possible. An easily identifiable disgruntled tenant could descend to the sub-lower depths and buy himself a one-way ticket to jail. A disappointed thief might have wreaked bloody murder on an entire family instead of learning how to pick wealthier victims. But it would take a nearly fatal dose of invention to make those characters stand up on their own two feet and go into action.

The Armanious execution has all the hallmarks of ritual murder. Members of the Egyptian Copt community in America know this custom too well to ignore the telltale signs. A small handful of courageous community leaders, specialists, and journalists have come forth to soberly present the case for ritual murder as a serious hypothesis that should not be excluded. Are they motivated by hatred of Islam? What then of the champions of Islam as a religion of peace? Since it is impossible to deny the precept of ritual murder, its history and widespread current practice, the primary concern of a religion of peace would be to explain to the faithful, and especially the faithful living in Western democracies, that ritual murder is forbidden. One does not smite infidels in America. Blasphemers are not punished by throat-slitting in Holland. Jews are not upstart dhimmis, fair game for slaughter in France.

What if some wayward creatures mistakenly believed that shariah should be imposed in Jersey City? Who will set them straight?

The slaughter of the Armanious family has been widely reported in the American press; it has not been mentioned in France. The ritual murder of Theo van Gogh caused a strong backlash in Holland. The beheading of Daniel Pearl was an introduction to the methods of 21st-century jihad.

The murder of Sebastien Selam, one of the most popular DJs in France, has been widely ignored. Sebastien lived with his widowed mother in a modest but comfortable low-rent apartment building in the 10th arrondissement, a half hour from the Place de la Republique. In November 2003, during the month of Ramadan, Sebastien was murdered by a neighbor, Adel Boumedienne. The Selams are Jewish, of Algerian origin; the Boumediennes are Muslims from Morocco. Relations between Jews and Muslims in the neighborhood, which had been normal or even cordial, radically deteriorated in the fall of 2000.There were incidents, anti-Semitic graffiti, ominous signs of violent hostility. And yet Sebastien let Adel get into his car as he was going into the underground garage to park. There, Adel slashed Sebastien’s throat almost severing his head, and mutilated his face beyond recognition with a carving fork. The coroner states in his report that he had never seen such severe mutilation in all his decades of practice.

Aside from a brief article filled with factual errors in the tabloid Le Parisien and an equally incompetent article in a Jewish weekly paper, there was hardly any press coverage of the Selam murder. When Israeli photographer Avi Rosen, who was in Paris at the time, heard what happened to the DJ, he immediately recognized the hallmarks of ritual murder. He took photos of the crime scene, interviewed the Selam family, and has stood by them ever since in their almost hopeless efforts to bring the murderer to justice and expose the true nature of the crime not only for the honor of Sebastien, but to warn others of the danger that confronts them.

Adel’s mother saw her son take the carving knife and fork from the kitchen; he came back a short time later, covered in blood, and told her, “I’ve killed my Jew, I can go to paradise.” He told the police that he had no remorse, no regrets, because Allah told him to kill Sebastien. They transferred him from the police station to a general hospital and from there to a psychiatric hospital. As of this writing, the Selam family lawyer is playing his last card; he has one last chance to convince the court to open an investigation. If the request is denied, the case will be closed. No investigation, no arrest, no trial. The murderer will some day be released from the mental hospital. The Selam family is sentenced to a life of mourning.

Chantal Piekolek was murdered in her shoe store in the 17th arrondissement of Paris earlier that same November day. The murderer, a hardened criminal recently released from prison, stabbed her 25 times. He was quickly apprehended and jailed, but died of cancer before he could be put on trial. Piekolek, who was Jewish, was murdered by a Muslim. Did he know she was Jewish? If robbery was the motive, why did he stab her 25 times? The mystery died with him. But one day the press, including the Jewish press, may be asked to explain why they transformed a Jewish divorcee – who had recently taken over a store after her father died – into the Christian widow of a Jewish husband. Why? Were two Jewish murders in one day during the month of Ramadan too much to bear? Or too much to hide?

Fiction is not divorced from reality, it is the art of bringing reality alive. When journalism strays so far from the truth, skittishly skirts the truth, closes its eyes to the obvious, and invents the preposterous, it encourages the very danger it is trying to avoid.

Ms. Poller is a novelist living in Paris.