Jerome Corsi sued Infowars founder Alex Jones on Thursday, heating up the feud between two of the nation’s top conspiracy theorists.

Corsi and his lawyer, conservative activist Larry Klayman, are both named as plaintiffs in the case against Jones, Infowars, Jones’ father David Jones, and Infowars host Owen Shroyer. The complaint alleges the defendants defamed Corsi and Klayman by questioning their mental fitness, with Jones saying that Corsi has dementia and has become “extremely mentally degraded.”

Infowars and Jones didn’t respond to requests for comment.

In their lawsuit, Corsi and Klayman allege that Jones and Infowars are hurting their careers as rival right-wing commentators, costing them “financial support and sales.”

Corsi and Jones weren’t always at odds. A year ago, Corsi, a promoter of conspiracy theories like the “birther” claim that Barack Obama was born in Kenya, worked as Infowars’ Washington bureau chief. He appeared at events with Jones and went on Jones’ Infowars show. After Corsi left Infowars last June, the outlet paid him a hefty $15,000 monthly severance for six months.

But Corsi’s relationship with Jones has soured as Special Counsel Robert Mueller investigates whether Corsi connected the Donald Trump campaign with WikiLeaks founder Julian Assange during the 2016 presidential election. The connection allegedly came through Trump adviser Roger Stone, himself an Infowars host who was arrested and charged with lying to Congress in January.

As Mueller’s investigators closed in, Corsi became unusually vocal about the investigation and hinted that he might cooperate with Mueller, prompting former allies like Jones and Stone to attack his credibility.

Corsi’s lawsuit mentions several attacks Jones and Stone have made on him through Infowars. In an October video, Jones claimed Corsi has dementia, and that he once saw Corsi lying on the ground at a steakhouse. In January, Stone, who is already being sued by Corsi in a separate lawsuit, said Corsi has a “feeble, alcohol-affected memory.”

Stone has also attacked Klayman, a right-wing lawyer notorious for his courtroom antics.

“He’s an egomaniac, and he could be the single worst lawyer in America,” Stone said in one video mentioned in the lawsuit. “With him as Jerry Corsi’s lawyer, Corsi may get the electric chair.”