The Justice Department will open a full criminal investigation into the 2005 destruction of CIA tapes showing the interrogation of two Al Qaeda suspects, FOX News has learned.

Investigators had opened a preliminary inquiry into the matter following media reports in December revealing the tapes' destruction.

"Following a preliminary inquiry into the destruction by CIA personnel of videotapes of detainee interrogations, the Department's National Security Division has recommended, and I have concluded, that there is a basis for initiating a criminal investigation of this matter," Attorney General Michael Mukasey said in a prepared statement Wednesday.

Mukasey said that just because a criminal probe is being opened does not mean that criminal charges will be filed.

The tapes reportedly showed the use of harsh interrogation methods, including waterboarding, which is banned by the Army Field Manual, but allowed for nonmilitary U.S. agencies such as the CIA. The tactic — thought by many to be torture — makes its subjects feel like they are drowning.

Mukasey also said that he is appointing an outside prosecutor to handle the investigation because the office that would normally handle the case — the U.S. Attorney's office for the Eastern District of Virginia — is where the CIA is located. Instead, John Durham, the first assistant U.S. attorney for the District of Connecticut, will take the lead.

Mukasey has said the department would pursue any and all information turned up by the preliminary inquiry, and would take appropriate legal action if wrongdoing was uncovered.

The initial inquiry was launched just days after the first reports of the tapes' destruction came out.

FOX reported the developments on the night of Dec. 6, after CIA Director Michael Hayden issued a statement to his employees about the issue. The statement was intended to take some of the steam out a New York Times story on the tapes that ran published in editions the next day.

CIA Inspector General John Helgerson on Wednesday issued a statement saying that while he assisted in the preliminary investigation, he would recuse himself from the new investigation.

"I anticipate describing fully the actions I and my Office took on this matter to investigators from the Executive and Legislative Branches," he said, adding: "It is important to avoid the conflict of interest, or even the appearance of conflict of interest, that surely would arise if I were also involved in the ongoing investigation."

A government official who declined to be identified told FOX News that the announcement was expected.

"Given the climate in Washington, D.C., the decision by the Department of Justice to move from a preliminary investigation to a criminal probe is one of the least surprising stories of 2008," the official said.

The official went on to explain that the prominence of the detaineee interrogation program — including waterboarding and alleged torture — in Mukasey's confirmation process for all intents and purposes forced the criminal probe.

"The bar is low to move from a preliminary investigation to a criminal probe," the official added.

The House Intelligence Committee, which is conducting its own probe of the tape destruction, will continue conducting its own probe, according to a Republican committee staff member.

"Given the failure to keep Congress fully and currently informed of the existence and destruction of these tapes and the apparent attempt to mislead the public about what the committee knew of the matter, the decision by the Department of Justice to initiate a criminal investigation only reinforces the significance and seriousness of the issues that are under review," said Jamal Ware, a senior intelligence committee adviser.

"We expect the Committee's investigation to continue moving forward on that basis," Ware said.

A Jan. 16. hearing before the intelligence committee is expected to feature Jose Rodriguez, the CIA official who ordered the tapes to be destroyed.

FOX News' Ian McCaleb, Catherine Herridge and Molly Hooper contributed to this report.