In the world of conspiracy theorists, Alex Jones and Wolfgang Halbig fueled each other’s darkest tendencies.

Soon after the Dec. 14, 2012, mass shooting at Sandy Hook Elementary School in Newtown, Conn., Jones, the right-wing provocateur, began spreading outlandish theories that the killing of 20 first-graders and six educators was staged by the government and victims’ families as part of an elaborate plot to confiscate Americans’ firearms.

Many of the most noxious claims originated in the mind of Halbig, a retired Florida public school official who became fixated on what he called “this supposed tragedy’’ at Sandy Hook. Court records and a previously unreleased deposition given by Jones in one of a set of defamation lawsuits brought against him by the families of 10 Sandy Hook victims show how he and Halbig used each other to pursue their obsession and promote it on the Internet.

Over several years, Jones made Halbig a guest on “Infowars,’’ his radio and online show. “Infowars’’ gave Halbig a camera crew and a platform for fund-raising, even as Halbig repeatedly visited Newtown, demanding thousands of pages of public records, including photos of the murder scene, the children’s bodies, and receipts for the cleanup of “bodily fluids, brain matter, skull fragments and around 45 to 60 gallons of blood.’’

Given practical support and visibility by Jones, Halbig hounded families of the victims and other residents of Newtown, and promoted a baseless tale that Avielle Richman, a first-grader killed at Sandy Hook, was still alive.

The deposition and its details about Jones’s operation and his interactions with Halbig was made public Friday, days after Avielle’s father, Jeremy Richman, killed himself in Newtown’s Edmond Town Hall, where the Avielle Foundation, a nonprofit organization dedicated to brain science that the family established in their daughter’s name, had an office.

The deposition and records are part of a defamation lawsuit against Jones brought by Scarlett Lewis, whose son Jesse Lewis died at Sandy Hook, moving forward in Texas. The families of Sandy Hook victims are suing Jones, “Infowars,’’ and associates such as Halbig in four lawsuits, one in Connecticut brought by eight victims’ families and a first responder, and three in Texas brought by parents of two more victims.

In the videotaped deposition, Jones says under oath that his sources for reports aired on “Infowars’’ include conspiracy theorists like Halbig, random e-mailers, and anonymous users on the chat room 4chan. Jones claims the First Amendment protection provided traditional news media for his false claims.

Jones acknowledged in the deposition that Halbig had been a considerable source of information for him about Sandy Hook. Asked by a lawyer for the families if he would agree that Halbig was “a raving lunatic,’’ Jones responded: “He seemed very credible and put together earlier on, but — I can’t remember the exact number — he seemed to get agitated about four years ago, three years ago.’’

The heightened profile Halbig gained through Jones and his skepticism about mass shootings drew him into the orbit of the National Rifle Association as well. On Feb. 15, 2018, the day after 17 people died in a mass shooting at Marjory Stoneman Douglas High School in Parkland, Fla., Mark Richardson, a program officer for the NRA, e-mailed Halbig to stir doubts about the facts of the shooting, according to a document in the Texas lawsuit that was first reported by HuffPost.

Referring to Sandy Hook, Richardson wrote to Halbig that “there is so much more to this story,’’ wrongly speculating in the message that the Parkland shooter “was not alone.’’ Halbig, 72, lives in a gated community in Florida with his wife and a white Havanese dog named Coco. He calls himself a “national school safety consultant’’ and former Florida state trooper, though his resume suggests he held the trooper job for at most a year in the mid-1970s. A 1999 Orlando Sentinel report quotes him as Seminole County public schools’ security director, saying a school shooting “can happen any time, anywhere.’’

Halbig frequently says that as soon as his demands for information are met he can “get back to my life with my grandchildren.’’ But when unsuccessful in getting the information he is seeking, Halbig publishes the personal information of his targets, spurring torrents of abuse and threats.

“I’ve said nobody died,’’ Halbig said in an interview last month, but “I’ve never ever been given the documents to form a true and honest opinion. We want to know the truth so we can teach other school districts to prevent this.’’ Halbig did not respond to e-mails and telephone messages requesting comment for this article.

While not the only person to pursue the families, Halbig has been particularly relentless. And as “Infowars’’ raised Halbig’s profile, the victims’ families and Newtown officials have struggled to stop him. He repeatedly has asked Newtown educators to give him the identities of children from the Sandy Hook choir who performed in a salute to the victims at the 2013 Super Bowl, seeking to “prove’’ Avielle and other dead children attended.

In 2015, police stopped Halbig and an “Infowars’’ crew from filming residents and children outside St. Rose of Lima Catholic church and school in Newtown. Exhibits in the Texas case viewed by the New York Times include a letter from an official at the Diocese of Bridgeport, Conn., ordering Halbig to stay away.

Halbig sent reams of rambling, misspelled e-mails to “Infowars’’ and others asserting that Avielle Richman is living under an assumed name with another family in Newtown, repeatedly naming the other girl online, the families’ lawyers said.

In the wake of Richman’s suicide, his family has appealed for privacy, and police have not released the contents of a note he left. There is no public evidence of a link between the suicide and the activities of Halbig and Jones. But his death has surfaced more outrage from the Sandy Hook families about the harassment they have endured, and calls to do more to stop it. Neil Heslin, whose son Jesse Lewis died in the same Sandy Hook classroom as Avielle, said that for more than six years the shooting has been “a constantly publicized event, a political agenda and then you become a target of this conspiracy stuff? It has a tremendous effect on you.’’

At the time of his death, Richman and his wife, Jennifer Hensel, were among the eight Sandy Hook victims’ families suing Jones, Halbig, and “Infowars’’ for defamation in Connecticut.

Halbig has attended hearings on his public records requests in Newtown with an “Infowars’’ camera crew in tow. He has repeatedly posted photos of Avielle and a girl who lives in Newtown online, with an “expert’’ analysis contending the images depict the same child.

Nelba Marques-Greene, whose daughter Ana perished at Sandy Hook, called Halbig “a certified lunatic’’ on Twitter after he posted harassing messages to her last month. “I’m like — for real you think we faked this?’’ she wrote. “You think first responders did? What a depraved mind.’’

Another parent, Leonard Pozner, whose son Noah died in the same classroom as Ana, reported the abuse, and after six years of appeals, Twitter suspended Halbig’s account last month. Pozner founded the HONR Network, a nonprofit combating online hate, after Noah was targeted by the conspiracy theorists.

Halbig has raised at least $100,000 to finance his records quest, according to Pozner, whose HONR Network volunteers reported Halbig’s activities to GoFundMe, successfully getting his fund-raising page taken down.

Pozner at first tried to engage Halbig, asking to speak with him in a 2014 e-mail. He received a response, viewed by the Times, from Kelley Watt, one of Halbig’s fellow hoaxers. “Wolfgang does not wish to speak with you unless you exhume Noah’s body and prove to the world you lost your son.’’

Halbig helped spread a 100-page background check containing Pozner’s addresses, relatives’ addresses, and Social Security number among the hoaxer community. Pozner and Noah’s mother, Veronique de la Rosa, live in hiding as a result of harassment.

In his deposition, Jones acknowledged that some of what Halbig and others were telling him about what happened at Sandy Hook “was not accurate.’’ But he also said that “retired FBI agents and . . . people high up in the Central Intelligence Agency have told me there is a coverup in Sandy Hook.’’