Drew Griffin interviewed Couy Griffin in an unsettling report that ran on Anderson Cooper 360 on Friday, during which the county commissioner pushed the outlandish conspiracy theory.
Mr Griffin, the founder of Cowboys for Trump, said in an interview with journalist Mr Griffin that he believed both Sicknick and Ashli Babbitt are still alive.
Sicknick, a Capitol police officer, suffered two strokes and died of natural causes a day after fending off rioters.
Babbitt, an Air Force veteran, was shot by an unidentified officer while trying to climb through the broken window of a barricaded doorway.
Mr Griffin was asked by Drew Griffin during the interview whether he believed “Officer Sicknick died because of the riot” to which he replied: “I’m not even so sure that Officer Sicknick’s even dead.”
The CNN reporter looked on in disbelief as Mr Griffin continued: “I’m serious. That’s, that’s how – and I hate to be so crazy conspiracy-minded ... I’m not even so sure Ashli Babbitt is dead.”
The Trump supporter questioned the legitimacy of her death by asking “have you seen anything of any of her family?”
To undermine the conspiracy theory, Drew Griffin then cut to an interview with Babbitt’s brother, Roger Witthoeft, during which he spoke emotionally about the loss of his sister.
Back in the studio, Drew Griffin said that Mr Griffin was “so far off the rails” going as far as to call him “brainwashed”. “He is out there. He still believes this stuff,” the CNN reporter said.
The leader of the right-wing group was arrested for his alleged role in the riots on 6 January during which pro-Trump rioters stormed the Capitol in a bid to overturn the 2020 election result.
Mr Griffin has denied the federal charges of knowingly entering or remaining in any restricted building or grounds without lawful authority.
The Daily Beast reported that Mr Griffin had previously met with Mr Trump “several times”. During one meeting he was photographed alongside the former president.
Additional reporting by the Associated Press