A woman in Florida was charged with making death threats to the father of a boy who was killed in the Sandy Hook Elementary School shooting massacre — threats she made because she believed the attack was staged.

In 2012, Noah Pozner, 6, was shot to death, one of the victims of the Sandy Hook massacre in Newtown, Conn., in which a gunman killed 27 people, including 20 young children at an elementary school, before turning the gun on himself.

Earlier this year, the boy’s father, Lenny Pozner, objected to a professor who has repeatedly argued that the massacre was an elaborate hoax, and the professor was fired. Afterward, Pozner started receiving death threats on his phone.

He was with his daughters when he checked his voicemail, but he quickly shut it off, alarmed.

“You’re gonna die you [expletives and slurs deleted],” he heard.  “… And what are you going to do about it?

“You can do absolutely nothing. … this is coming to you real soon [expletive deleted]. You going to die,” and “You [expletive deleted] look behind you, justice is coming to you real soon.”

Pozner was jolted, he said, not just because of fear but he worried that his children might hear it.

Lucy Richards, 57, of Tampa, was arrested Monday after a grand jury indictment on four felony counts of transmitting threats, the U.S. Justice Department said in a statement.

A year ago, Noah Pozner’s parents wrote a letter to the Sun-Sentinel, saying that a professor at Florida Atlantic University had harassed them for proof that the murders really happened, and arguing that his position at the university gave his claims unjustified credibility.

James Tracy was fired by the university.

A post apparently written by Tracy maintained that Sandy Hook was faked, that no one was killed and that  “local co-conspirators” were paid to pretend to grieve their young children.

Tracy sued the university. He did not immediately respond to a message seeking comment Wednesday night.

Then the threats against Pozner intensified. He knew there were people who contended that the shootings never happened, that paid actors staged the tragedy in an effort to promote gun control. But he was surprised by the intensity of the reaction when he questioned the conspiracy theory.

He noted that such conspiracy theories have had similarly unusual reactions, such as when a gunman walked into a pizza restaurant in Washington, D.C., on Sunday and fired shots, later telling police he was searching for child abuse victims because of a conspiracy theory that went viral.

In January, after the death threats, Pozner wrote, “It’s been three years since my son’s life was snuffed out by an act of senseless violence and I’m left in a fog of disbelief.”

On Wednesday, he said he was comforted to know the system was working, to protect the victims of violent crimes from re-victimization.

“This is a heavy month,” he said. Next week is the fourth anniversary of the shooting.

Correction: An earlier version of this story gave an incorrect first name for Noah Pozner. The story has been updated.