Linda Beigel Schulman does not have the luxury of believing in conspiracy theories. She knows that no amount of magical thinking can bring her son back. She knows exactly how long he’s been gone. She knows because she does not have the luxury of forgetting.

“It’s been one thousand and seventy-nine days since the murder,” she said, “I count every day. I will count every day for the rest of my life.”

Scott J. Beigel was killed on February 14, 2018, when a gunman opened fire inside Marjory Stoneman Douglas High School in Parkland, Florida. Beigel taught ninth-grade geography and coached the cross-country team. Two other teachers and 14 students were killed alongside him. It was one of the deadliest school shootings in American history.

Linda knows it happened because she fought with the county sheriff for access to the security-camera footage from that day. She was granted permission to watch the moment her son’s life was taken. The video shows how he opened the door to his classroom and stepped into the hallway to wave students fleeing the shooter to safety. Before he could lock the door again, the shooter, dressed for a war, fired in his direction. His blood fell onto the vinyl floor and he collapsed. She knows it happened because he was laid to rest in a mausoleum in Boca Raton, Florida. She knows it happened because he isn’t here anymore.

Linda and her husband, Michael, responded to the loss not by denying what happened, but by doing their best to carry on in a way that would honor their son. They founded a charity that raises money to send disadvantaged children touched by gun violence to summer camp. They lobby lawmakers for gun safety. They’ve tried to make it so that Scott’s absence from their lives doesn’t mean their lives are empty. In 2019, they invited me to a Mets game with a bunch of kids they’d been able to send to camp. They’re proud that they can do things like that. But the reason why hangs over them. They still don’t have their son.

That would be true no matter what, but there are ghoulish people who seem intent on reminding them. Those people believe mass shootings are “false-flag operations” in which “crisis actors” stage a phony violent attack in order to foment fear of guns so that the government can disarm its citizenry. Once pushed to the fringes of our society, such conspiracy theorists have been empowered and mainstreamed over the last decade, in which a fellow conspiracy theorist was elected president for one term thanks, in part, to their support.

The rise of QAnon, the convoluted conspiracy that baby-eating, child-sex-abusing elites control the world, has brought more former outcasts to Washington, such as Marjorie Taylor Greene, the Republican who represents Georgia’s 14th district in the new Congress. Last week, Media Matters reported that Greene had endorsed and promoted the lie that Parkland was a “false flag” in since-deleted Facebook posts. On Wednesday, video surfaced from 2019 of Greene harassing David Hogg, a Parkland survivor turned gun-safety activist, in Washington, where he was meeting with lawmakers.

It was too much for Linda Beigel Schulman and Michael Schulman. Linda and Michael are decent and responsible people. They understand that responding to Greene means giving her more attention, and that more attention carries the risk of her message reaching more people than it already has.

But they believe that the best way to stop the spread of a lie is to confront it with the truth. And so on Wednesday, the one thousandth and seventy-ninth day since Scott J. Beigel was murdered, they decided to respond.

“Congresswoman Marjorie Taylor Greene, the shooting where my son was murdered protecting his students was not a ‘false flag,’” Linda said in a statement to New York. “It was not staged. It really happened. Do not trivialize my son Scott’s sacrifice to save his students for your own political gain. As Joseph Welch said to Sen. Joseph McCarthy Senate Permanent Subcommittee on Investigations in 1954: ‘Until this moment, Senator, I think I never really gauged your cruelty or your recklessness. Have you no sense of decency?’ Congresswoman Greene, I ask you the same question. Are you that cruel? HAVE YOU NO SENSE OF DECENCY??”

“What do we need to do?” Linda asked me, her voice cracking. “Show her the video? Do I need to take her over to Scott’s mausoleum? Does she need to see how he was shot six times from three feet away?”

“It’s wrong,” she said. “It’s just wrong.”

Greene did not respond to a request for comment.