Rudy Giuliani said Special Counsel Robert Mueller's Russia investigation may be "tainted" and "infected with bias" following revelations from Justice Department Inspector General Michael Horowitz.

During his testimony before Congress, Horowitz said that anti-Trump text messages between FBI agent Peter Strzok and FBI attorney Lisa Page created the appearance that investigative decisions were impacted by bias or improper considerations.

Although Horowitz maintained that bias did not affect the outcome of the Hillary Clinton email probe, he confirmed that his office was looking into whether Strzok's anti-Trump bias played a role in the launch of the bureau's Russia probe.

On "America's Newsroom," Giuliani said Strzok was removed from Mueller's probe, but the controversial FBI agent may have left behind some of his similarly biased "cohorts" on Mueller's team.

Gowdy Takes Justice Dept IG to Task: Biased FBI Agents 'Prejudged Outcomes' of Clinton & Russia Probes

'Dangerous to Democracy': Sen. Graham Slams DOJ & FBI's Handling of Clinton Email Probe

"If that's the case, then how can you trust anything they're doing in this investigation?" Giuliani said. "We have to investigate the investigators, in order to determine if it's a valid investigation."

As for speculation that he will recommend President Trump not testify before Mueller's team, Giuliani said that will depend on the stipulations and how narrow the questioning would be.

"[He] certainly won't sit down with him with these questions still lingering about whether these people are a kangaroo court and a firing squad," Giuliani said. "Who in his right mind would put their client in front of people like that?"

Watch the interview above, including Giuliani explaining why he thinks former FBI Director James Comey is going to jail.

Rep. DeSantis: Russia Probe Was 'Infected by Bias,' Legitimacy Is 'Gone'

WATCH: Woman in Capitol Yells 'F*** You' at Trump, Entourage

Hannity to Strzok: 'You Have the Right to Remain Silent, I Suggest You Use It'