The brother of Seth Rich, the slain Democratic National Committee staffer whose unsolved murder became the basis for conspiracy theories on the far-right, filed a lawsuit on Tuesday against individuals and media organizations that he alleges peddled false and unfounded claims about him.

The lawsuit, filed by Aaron Rich in US District Court in the District of Columbia, accuses Ed Butowsky, a wealthy Texas businessman; Matt Couch, a fringe internet activist; America First Media, Couch's media company; and The Washington Times, a conservative newspaper, of acting "with reckless disregard for the truth."

Seth Rich was fatally shot in Washington, DC, in July 2016. Police have said evidence indicates he was the victim of a botched robbery, but in the wake of his death, far-right activists and media organizations suggested something far more sinister. Without real evidence, they peddled a conspiracy theory that said Seth Rich leaked a trove of DNC emails to Wikileaks and was killed in retribution for the supposed leak. The theory was convenient for some on the right as they disputed allegations Russia hacked the DNC, something President Trump had raised doubts about.

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Aaron Rich's lawsuit seeks damages for harm to his reputation and emotional distress, among other things, against Butowsky, Couch, America First Media, and The Washington Times for suggesting he played a role in the supposed email theft.

The suit alleges those people and media companies pushed a conspiracy theory about Aaron Rich that used his background as a defense contractor with technical expertise to suggest he worked with his brother to leak DNC documents to Wikileaks, received money for doing so, and then worked to cover-up the crime.

"Not satisfied with the existing conspiracy theory about Seth Rich ... Defendants Ed Butowsky, Matt Couch, and America First Media have spent the past year creating and disseminating a made-up conspiracy theory that Aaron Rich was the technological know-how behind, and financial beneficiary of, Seth's operation," Michael Gottlieb, an attorney for Aaron Rich, told CNN.

Among the body of evidence cited in the lawsuit is an August 15, 2017, Periscope video hosted by Couch. Butowsky, according to the lawsuit, joined the Periscope video as a participant in the chatroom and wrote that "Aaron Rich needs to come out and admit money in his account." Couch, the lawsuit says, replied, "Ed just put it out there—Aaron Rich accepted money. Aaron Rich had money from WikiLeaks go into his personal account. Think about that. Aaron Rich had WikiLeaks money go into his personal account. Ok?"

The lawsuit cited numerous other examples of Couch making similar claims about Aaron Rich.

Related: Family of slain Democratic staffer Seth Rich sues Fox News

The lawsuit also cited a March 1, 2018, commentary piece in The Washington Times. The article, which the lawsuit says was published both online and in print, said it was "well known in intelligence circles that Seth Rich and his brother, Aaron Rich, downloaded the DNC emails and was paid by Wikileaks for that information." The article cited no evidence to support the assertion. The Washington Times did not remove or retract the article after "receiving notice of the falsity of the statements about Aaron after the publication," the lawsuit says.

"Our constitutional system leaves wide room for debate on issues of public concern, but individuals like Defendants poison that deliberate space when they flood it with fabricated information about private figures like Aaron," the lawsuit says, adding, "Defendants are entitled to their own opinions, but they can and must be held accountable for their lies."

Butowsky told CNN shortly after the lawsuit was filed that he had no idea what Aaron Rich was "talking about" and only had one additional question: "I have nothing else to say, other than how many more family members do the Riches have that want to sue me?"

Couch said in a Periscope video that he learned of the lawsuit from media reports and was "being sued for investigating the truth." He then signaled to his audience that he would not back down.

"You're not going to detour us from investigating this and reporting the truth," he said. "And what you've done now is you've opened yourself up to a discovery phase. A discovery phase. Which means now I can subpoena your phone records, the laptops, your cell phones. And guess what folks? I want it all."

Representatives for The Washington Times did not immediately respond to requests for comment.

Aaron Rich's lawsuit comes just weeks after the parents of Seth Rich sued Fox News and Butowsky for their role in peddling the Seth Rich conspiracy theory. Butowsky told CNN that lawsuit "doesn't make any sense to me," and a Fox News spokesperson did not respond to a request for comment. Previously, Rod Wheeler, a private investigator Butowsky had hired to investigate Seth Rich's death, sued Fox News and Butowsky, claiming the two concocted the conspiracy theory with oversight from the White House. Butowsky called that lawsuit "bulls**t" and Fox News has asked for a court to dismiss it.