Lawyers representing several families of victims of the 2012 shooting at Sandy Hook Elementary School said in court documents that the legal team acting for Alex Jones, the conspiracy theorist and host of the Infowars website, sent them child pornography, which they reported to the F.B.I.
The families have filed a defamation suit against Mr. Jones, who has spread the false claim that the shooting in Newtown, Conn., was an intricate hoax.
In a filing on Monday in a Connecticut court, lawyers for the families said consultants reviewing documents submitted by Mr. Jones’s lawyers as part of the suit had found an image that “appeared to be child pornography.”
Mr. Jones learned about the accusation earlier as part of the discovery process. On his show on Friday he forcefully denied any involvement in the material in question being sent and accused Chris Mattei, one of the lawyers representing the Sandy Hook families, of trying to frame him.
“You’re trying to set me up with child porn,” Mr. Jones said. “One million dollars to put your head on a pike.”
Norman Pattis, a lawyer for Mr. Jones, said that the allegation had already been investigated by the F.B.I. and that Mr. Jones had been cleared of any wrongdoing.
“For two weeks the F.B.I. conducted an inquiry and I learned on Wednesday of this week that that inquiry concluded that no one here has any guilty knowledge of those emails, indeed there is no reason to suspect anybody even knew they were here,” Mr. Pattis said on an Infowars broadcast on Saturday.
“The attempt to use this as a litigation club is the worst form of special pleading and the plaintiffs’ lawyers know it,” Mr. Pattis added.
Calls to the F.B.I. office in New Haven on Monday were not immediately returned.
“It is worth noting that if the Jones defendants had engaged in even minimal due diligence and actually reviewed the materials before production, they would have found the images themselves,” the lawyers for the families, who are with the law firm Koskoff Koskoff & Bieder, wrote in their filing.
Mr. Mattei, through a representative, declined to comment beyond the filing.
The plaintiffs in the suit are relatives of five children and three adults killed in the shooting, along with one F.B.I. agent who responded to the scene.
They have accused Mr. Jones of spreading spurious claims that have subjected them to physical and verbal harassment, death threats and sustained attacks on social media. Mr. Jones amplified conspiracy theories claiming that the relatives of victims were actors involved in an elaborate ruse meant to confiscate firearms from law-abiding citizens.
A separate defamation suit is also moving forward in Texas, Mr. Jones’s home state.
The plaintiffs in both lawsuits have achieved a series of victories in recent months, with judges in Texas and Connecticut ordering that Mr. Jones and others connected to his businesses had to testify or submit to questioning by the families’ lawyers.
Mr. Jones has also come under intense scrutiny and has seen the reach of his platform diminish considerably after he was barred by Facebook, Twitter and YouTube. A deal for his program to be shown on the Roku streaming service fell apart after public outrage.
The Connecticut lawsuit against Mr. Jones reflected one of the ways the anguish in Newtown has endured and evolved in the years since the attack when a gunman stormed into the elementary school and killed 26 people, including 20 first graders, in a spray of gunfire.
At the time, the attack traumatized the country and made Newtown one of several communities that have come under the spotlight as a result of horrific violence.
But in more than six years since, it has also been an unsettling example of the ways a tragedy lingers in a community and continues to send out ripples of grief.
In March, Newtown was shaken once again after the apparent suicide of Jeremy Richman, whose 6-year-old daughter, Avielle, was among the children killed and who was part of the lawsuit against Mr. Jones.
The Koskoff law firm also represents the families in a separate suit against the companies that manufactured and sold the weapon used by the gunman, Adam Lanza, during the attack.