A few weeks before he was fired by President Trump in May 2017, then-FBI Director James Comey testified before the House Intelligence Committee. During that testimony, he confirmed something that had already been reported.

“I have been authorized by the Department of Justice to confirm that the FBI, as part of our counterintelligence mission, is investigating the Russian government’s efforts to interfere in the 2016 presidential election,” he said, “and that includes investigating the nature of any links between individuals associated with the Trump campaign and the Russian government and whether there was any coordination between the campaign and Russia’s efforts.”

To a layperson, this issue may seem to be resolved. Special counsel Robert S. Mueller III completed his work in March, after all, finding insufficient evidence to establish that Trump and his campaign coordinated with the interference effort undertaken by the Russian government.

But, in fact, it isn’t. Mueller’s investigation into possible coordination was an offshoot of a broader probe into how or where members of Trump’s team — the candidate included — might have been working to aid Russian interests.

Where that investigation stands now, though, is a mystery — even to congressional leaders. House Intelligence Committee Chairman Adam B. Schiff (D-Calif.) spoke with The Washington Post by phone Tuesday and explained how he and his colleagues have been stymied in their efforts to learn how and if the probe is moving forward. The interview has been edited for clarity.

The Post: What, as you understand it, is the current status of that investigation into the president?

Schiff: The short answer is: We don’t know. Just as a reminder, this all began as an FBI counterintelligence investigation into whether people around then-candidate Trump were acting as witting or unwitting agents of a foreign power. So it began as a counterintelligence investigation, not as a criminal investigation. Now obviously a criminal case — many criminal cases — were spun off of this but we don’t know what happened to the counterintelligence investigation that James Comey opened.

We would get briefed, predominantly at a Gang of Eight level, up until Comey was fired. And, after that point, while we continued to get quarterly — although often they missed the quarterly nature of it — counterintelligence briefings, they excluded the most important counterintelligence investigation then going on, that involving Donald Trump.

The Post: Is there any reason to believe that the counterintelligence investigation has been closed?

Schiff: You know, I have not been able to get clarity on that. We have been seeking to get it, to get an answer from the Justice Department, from the counterintelligence division at the FBI, and we don’t have clarity, which is concerning.

There is a reference in the Mueller report to counterintelligence FBI personnel who were embedded in Mueller’s team [Volume One, p. 13] which then reports back to headquarters, although those reports may have dealt with counterintelligence issues that the special counsel felt were beyond his scope. But we don’t know whether the Mueller team itself or others in the Mueller team or others outside the Mueller team continued the counterintelligence investigation after the criminal probe was opened or whether at some point it was closed.

The Post: NBC News reported that there was supposed to have been an update on this shortly after the Mueller report came out. That just didn’t happen?

Schiff: We have had a number of discussions now with the Department of Justice and the FBI, but on this point, we still have not gotten clarity, and that does concern us. There is a statutory obligation by the department to keep us currently and presently informed of significant counterintelligence matters, and it’s hard to imagine one more significant than this. So I’m confident we will get an answer, but they’ve yet to be forthcoming on that point.

The Post: As you noted, there is some overlap between what the special counsel was looking at and some elements of the original counterintelligence investigation. What do you see as the important distinctions? What are the things that really stand out from the counterintelligence probe that wouldn’t have been covered under what Mueller was actually looking at?

Schiff: Well, that’s a very good question and really at the heart of why we want to get a briefing and the counterintelligence materials and findings, because we don’t know. Now, certainly some of what Bob Muller wrote about in this report, a great deal of Volume One is counterintelligence information.

The fact that the president, while concealing it from the country, was seeking to make money in Russia, building a massive tower in Moscow and was seeking the Kremlin’s help and then misleading the country and ultimately, through Michael Cohen, the Congress is a counterintelligence nightmare of the first order. Because the Russians, of course, were on the other end of that transaction and knew that when the president was denying any business dealings he was lying. And, interestingly, when, the year after Michael Cohen’s testimony, it became known that he had lied to our committee and that the transaction had gone on much longer than he had said, and, in fact, they had reached out directly to [spokesman for Russian President Vladimir Putin] Dmitry Peskov for help from the Kremlin. Someone very close to Putin, Peskov issued a statement denying that they had ever followed up on the inquiry. And Peskov was lying. So here you have the prospect of the Kremlin issuing its own false statements to help cover up for the president of the United States.

And so those are quintessential counterintelligence issues. It may not be a crime for a candidate for a president to seek to make money from a hostile foreign power during an election and mislead the country about it. Maybe it should be, and given [Trump attorney] Rudy Giuliani’s aborted trip to Ukraine, they clearly haven’t learned the lesson from 2016. But the counterintelligence concerns go beyond mere violation of criminal law. They’re at one time not necessarily a criminal activity and at the same time potentially far more serious than criminal activity because you have the capacity to warp U.S. policy owing to some form of compromise.

The Post: There has been a subpoena that’s been issued. I saw your interview with Axios on Friday in which you suggested that you might use inherent contempt power to try to fine people who weren’t being responsive to subpoenas broadly. How confident do you feel that you will get a response to the subpoena? How confident do you feel that you will be able to be effective in, if you choose to use the inherent contempt power, how confident you feel that that will actually be an effective tool?

Schiff: Well, I certainly think the president and his lawyer [Attorney General] Bill Barr are being fully obstructive and have adopted a maximalist position of no documents, no way, no how.

But, you know, we are having negotiations over the counterintelligence information that we hope will nonetheless bear fruit. I think the FBI and the intelligence community understand their statutory obligations but they’re caught between a rock and a hard place. While they have a good relationship with our committee and continue to work with us on a whole range of issues, I think that the position the president and Bill Barr have taken makes it very difficult for them to produce the materials they know they’re obligated to. We’re making every effort to achieve compliance without having to litigate the matter. But if necessary, we will.

The Post: The natural follow-up question, particularly given not only your having used the word “obstructive” there but given the recent developments is: How confident do you feel that if there is an ongoing counterintelligence investigation that it will be protected, that it will actually be able to carry to fruition?

Schiff: I think all of us have deep concerns with the attorney general’s conduct and, now, opening some form of investigation of the president’s rivals. The whole adoption of the “Deep State coup” theory, the “spying on the campaign” theory, promulgated by the president through his Twitter account, that is now apparently the policy of the attorney general of the United States, who sees nothing wrong with opening up investigations of rivals that are requested by the president.

And if that’s the case then, yes, it certainly ought to concern us that an attorney general who believes that the president at any time could shut down the special counsel’s investigation because he deemed it unfair could also shut down any counterintelligence investigation for the same reason.

The Post: Do you plan on subpoenaing anyone for testimony in regards to the investigation?

Schiff: That very well may be necessary. We’re talking to a number of witnesses that we’d like to come before our committee. We certainly have every expectation that Bob Mueller will come and testify and we hope that we can organize that without necessity of using any subpoena. I think Bob Mueller’s probably more than willing to testify. I think he understands the importance of it. May or may not look forward to it. I can certainly understand it’s going to be an arduous experience under the best of circumstances, but I think he understands just how important it is for the country to hear directly from him, particularly when the attorney general has so badly misled the public about his report and its conclusions.

There is a lot more at stake here than oversight of the Russia investigation or even oversight of Donald Trump. If Donald Trump, through release obstructionist tactics, can thwart congressional oversight, it means that every president who follows him can do the same. And that will fundamentally alter the balance of power in a way that will make it far more difficult to ferret out corruption and malfeasance of any future president.