Investigators examining the origins of the Russia investigation should "let it all come out and pursue the truth," said Chris Wallace, the host of "Fox News Sunday."

U.S. Attorney John Durham's ongoing probe into potential FBI and Justice Department (DOJ) misconduct in the Russia investigation has transitioned into a full-fledged criminal investigation.

What prompted the change is unclear, but a source told Fox News that DOJ Inspector General Michael Horowitz's upcoming report on alleged FBI surveillance abuses against the Trump campaign will shed light on why the probe has shifted to a criminal inquiry.

Horowitz announced on Thursday that his report would be available to the public soon, with "few" redactions.

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Fox News reported on Tuesday that Durham's probe had expanded significantly based on new evidence uncovered during a recent trip to Rome with Attorney General William Barr.

Appearing Friday on "America's Newsroom" with anchor Sandra Smith, Wallace said that "something obviously came up."

According to Wallace, the investigation's "new status" means that "they can impanel a grand jury and bring people up to testify before the grand jury. They can subpoena people and, yes, they can bring criminal charges."

He said that it "obviously puts [the investigation] on a new footing."

The investigation's new status means Durham can subpoena witnesses, file charges, and impanel fact-finding grand juries.

Meanwhile, Democrats are hammering the move.

House Judiciary Chairman Jerrold Nadler and House Intelligence Committee Chairman Adam Schiff released a statement saying that the reports, "raise profound new concerns that the Department of Justice under Attorney General William Barr has lost its independence and become a vehicle for President Trump's political revenge. If the Department of Justice may be used as a tool of political retribution, or to help the President with a political narrative for the next election, the rule of law will suffer new and irreparable damage."

The Judiciary Committee's ranking member, Rep. Doug Collins, responded via Twitter: "If Durham finds crimes were committed, I'm confident he'll pursue justice and help restore America's confidence in our premier law enforcement agency. Chairman Nadler is wrong to suggest this investigation is anything less than an effort to deliver truth and accountability."

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"And, if you're one of the people that were involved in the Trump Russia investigation in 2016 -- whether it's James Comey or Andrew McCabe or Strzok or Page or all of those people -- they now face the greater possibility, not the certainty, but the possibility of legal jeopardy," Wallace told Smith.

"I have to laugh because you see the Republicans attacking the Democrats for the impeachment investigation, and now you see the Democrats attacking the Republicans for this investigation," he noted.

Fox News' Gregg Re, Jake Gibson, and Ed Henry contributed to this report.