President Donald Trump questioned the validity of the ongoing Russia investigation on Wednesday after some of the agents who began the process were fired.

“The Rigged Russian Witch Hunt goes on and on as the ‘originators and founders’ of this scam continue to be fired and demoted for their corrupt and illegal activity,” Trump wrote on Twitter. “All credibility is gone from this terrible Hoax, and much more will be lost as it proceeds.”

Trump cited former FBI Assistant Director Chris Swecker, who said that the firing of agent Peter Strzok was a “step in the right direction.”

“The action was a decisive step in the right direction in correcting the wrongs committed by what has been described as Comey’s skinny inner circle,” Swecker said on Fox News on Wednesday, referring to former FBI director James Comey, Deputy Director Andrew McCabe, and Strzok.

He added that Comey’s team was using personal email addresses and sending classified information on them while investigating Hillary Clinton and portraying themselves as heroes.

“The actions by Strzok, Comey and McCabe disgusted me and many of the dedicated, loyal, patriotic and courageous men and women who have served in the FBI – often willingly risking their lives in defense of our country,” Swecker wrote in a Fox News op-ed: