The Senate Ethics Committee is beginning its investigation of allegations into leaks involving classified information by Sen. Richard Shelby (R-Ala.) — its first probe of a matter referred by federal law enforcement authorities to the panel in more than two years.

Justice Department officials considered the matter sensitive enough that they briefed the House and Senate Intelligence committees on their probe before the August recess began, just as they were referring the Shelby case to the Ethics panel, according to a federal law enforcement official.

The case involves information from a joint briefing for the House and Senate Intelligence committees that was subsequently reported on CNN back in 2002. Since news of the investigation became public, Shelby has denied that he ever leaked information that he knew to be classified.

While some press reports indicated that Justice’s criminal investigation was considered over, the law enforcement official stressed that the department still considers the case open. This sets up the possibility of concurrent criminal and ethics investigations by Justice and the Senate.

“It’s not closed — it remains open. The referral was made, but the case remains open,” the official said, speaking on the condition of anonymity.

It is not clear, however, how actively the matter is being pursued by Justice and its task force looking into the case, which included officials with the CIA and the National Security Agency.

While he has been notified by the Ethics Committee of the referral, Shelby has not spoken to any criminal investigators since the FBI conducted interviews with members of the Senate Intelligence Committee in the summer of 2002.

Shelby, whose term on Intelligence ended at the start of 2003, said in a statement released in late July: “My position on this issue is clear and well-known: At no time during my career as a United States Senator and, more particularly, at no time during my service as Chairman of the Senate Select Committee on Intelligence, have I ever knowingly compromised classified information.”

He continued, “To my knowledge, the same can be said about my staff. We have provided the investigation with our full cooperation in the past, and we will continue to do so.”

The Senate’s six-member Ethics Committee, which is evenly divided by party, has not met on the matter. Indeed, it has not met as a group on any matter in several months, a senior GOP source said.

And it may be many months before the full committee digs into the case, officials said, because the panel has in the past declined to take up a case in the midst of the campaign season. Shelby is an overwhelming favorite to win re-election, sitting on a campaign account currently worth more than $11.6 million.

The case focuses on CNN reports about NSA intercepts of terrorists talking about actions the day before the Sept. 11, 2001, attacks. In a highly unusual move, the chairmen of the Intelligence committees at the time — Sen. Bob Graham (D-Fla.) and Rep. Porter Goss (R-Fla.) — requested that Justice launch a criminal probe of the leak. This set up the unusual scenario of the committee being investigated by an agency it oversees.

Since CNN has not cooperated with the Justice probe, the matter does not appear to have gotten far, other than focusing on Shelby and a former press aide.

The first action the Ethics Committee would have to take may be to find a temporary member who can deal solely with the Shelby case. Sen. Pat Roberts (R-Kan.), who has been on Ethics for years, was a senior member of Intelligence at the time of the leak and is now chairman of that panel. This could put him in the awkward position of having to investigate, through Ethics, his own committee.

Roberts’ aides did not return calls seeking comment about whether he would seek to recuse himself from the Shelby probe. Ethics Committee aides declined to comment on all details of the case.

Referrals from Justice to the Ethics Committee are considered rare, although in January 2002, U.S. attorneys in Manhattan handed over their files from a four-year probe of then-Sen. Robert Torricelli’s (D-N.J.) personal and professional finances. That investigation ended with no indictments, although the ethics cloud hanging over Torricelli helped sink his re-election campaign.

On the House side, U.S. attorneys in Cleveland in the summer of 2002 handed over their files to the ethics committee in the case that ultimately landed then-Rep. James Traficant (D-Ohio) in federal prison.

In both of those instances, the House and Senate committees stood back and took no major investigative steps as the criminal investigation proceeded.

The House committee unanimously voted to expel Traficant after he was convicted on federal bribery, racketeering and tax evasion charges, an action that was approved by the full House in July 2002.

Torricelli, for his part, was given a letter by Senate Ethics that “strongly admonished” him for accepting thousands of dollars worth of gifts from a contributor. It was one of the weakest forms of punishment available to the committee, but served as a symbolic rebuke that effectively forced him out of his re-election race.

The Senate Ethics Committee, unlike its House counterpart, has no official timeline for handling cases before it. The House panel has rigid timetables that govern the different stages of individual probes.

Much of the Senate Ethics Committee’s power resides with its chairman, Sen. George Voinovich (R-Ohio), and the vice chairman, Minority Whip Harry Reid (D-Nev.). They have the power to dismiss cases without ever consulting the other four members of the panel.

In all likelihood, the committee’s nonpartisan staff will begin what is called a “preliminary inquiry,” which can consist of interviews and other investigative efforts.

In the Torricelli case, the staff’s preliminary inquiry yielded an initial report to the chairman and vice chairman — who at the time were Sen. Daniel Inouye (D-Hawaii) and Roberts — which they forwarded to the rest of the committee.

If Voinovich and Reid determine that the whole panel should review the Shelby case, the rest of the preliminary inquiry would continue. They could then determine one of three avenues to pursue, according to the Senate Ethics Manual.

At the end of the preliminary inquiry, the committee could vote to dismiss the case entirely, finding it to be of “de minimis” nature. They could also vote to issue a letter of admonition, which could be given privately or publicly. In Torricelli’s case, the admonition letter was released publicly.

Under the ethics manual, letters of admonition are not even considered disciplinary punishment.

If the panel deems the alleged infractions to be serious enough, it could launch a full adjudicatory review.

That would involve full-blown hearings, which could be held in public.

There has not been an adjudicatory review of a Senator since former Sen. Bob Packwood’s (R-Ore.) sexual harassment scandal in the early to mid-1990s.