Jillian Soto planned the day for months. It was the third annual race in honor of her sister Vicki Soto, a teacher gunned down at Sandy Hook Elementary School in Newtown, Connecticut, three years earlier. Thousands of people came out to run the November race and raise money for scholarships. The roads were dotted with pink flamingos, Vicki’s favorite bird. “People were sitting on the ground afterward, enjoying cupcakes,” Jillian recalls. A man approached, wearing a T-shirt that said Team Vicki. But he was not on the team.

He began taking a cell-phone video of Jillian and said he had some questions. He held up a copy of a photo he had found online. It was a picture of Vicki and her three siblings on a sunny Easter Sunday. “I knew right then and there that he was one of those people: a truther,” Jillian says. In other words, a conspiracy theorist who believes that the shooting was an elaborate hoax.

So-called gun truthers, or hoaxers, believe that mass killings, such as the one at Sandy Hook, were organized by the government to promote more restrictive gun laws. Some believe that no one died and actors played the parts of victims and grieving relatives. They call the events false flags, a military term for covert operations designed to deceive. Read more