At the end of the House Intelligence Committee’s long hearing on the FBI investigation of Russian meddling in the presidential election this week, the Republican chairman, Devin Nunes of California, made a last, vain attempt to clear the White House of suspicion.

Do you have any evidence, he asked FBI Director James Comey, that anyone in the Trump administration was working with the Russians?

“Not a question I can answer,” Comey answered implacably.

That drew a frown from Nunes. Comey’s silence put the White House under “a big gray cloud,” the congressman complained.

“The faster you can get to the bottom of this, it’s going to be better for all Americans,” he said.

On that count, Nunes is right. The FBI investigation is likely to take more than a year.

Counterintelligence investigators have more leeway than criminal investigators to seek evidence of foreign meddling -- including financial records.

But there’s always been one thing Nunes — and Trump, for that matter — could do to dispel the clouds around the administration: Join the call for an independent public inquiry and urge every Trump campaign aide to cooperate.

They haven’t done that. Indeed, Trump seems to be moving in the opposite direction. A few months ago, the president acknowledged briefly that Russia had tried to meddle in the election. This week, he was backsliding again, describing the whole affair (in a tweet) as “fake news” invented by Democrats to excuse their “terrible campaign.”

That’s not going to move Comey, a Republican former prosecutor with a well-developed sense of his own righteousness. He tormented Hillary Clinton throughout last year’s campaign; now, it appears, it’s Trump’s turn.

The headlines from the hearing went to Comey’s statement that his investigation includes “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.”

Less noticed, but just as important, was Comey’s description of the probe -- as a counterintelligence investigation, not a criminal inquiry.

At first glance, that might sound like good news for the White House. It suggests that the FBI has not found evidence that any federal crimes were committed.

But in the long run, that’s likely to prove cold comfort.

Unlike criminal investigations, counterintelligence probes aren’t aimed mainly at gathering evidence that crimes have been committed.

Instead, their main purpose is to determine what foreign powers, especially hostile powers, are doing inside the United States. They don’t always lead to criminal prosecutions.

“(Counterintelligence) investigations have to be very thorough. The FBI is going to look under every rock,” Donald B. Ayer, a top Justice Department official under President George Bush, told me.

That means the investigation is likely not only to be long, but also wide — potentially much wider than a simple criminal inquiry.

“This investigation is about what the Russians are up to, and whether there is Russian influence over US decision-makers,” said Jeffrey H. Smith, a former general counsel at the CIA. “It’s going to be very hard to limit it to the narrow question of interference in the election. It would be logical to look at whether there is any continuing influence over people close to the president, or the president himself.”

Also, counterintelligence investigators have more leeway than criminal investigators to seek evidence of foreign meddling — including financial records.

“They have considerably more leeway,” Smith said. “They can look at bank records, tax records. They’re likely to want to track down as many of Trump’s business partnerships and financial accounts as they can. Think of how long that’s going to take.”

Never mind how long it will take. Think of how unhappy the president will be when the FBI requests those records.

Comey’s decision to cast his inquiry as a counterintelligence effort has one more consequence: Once the probe is complete, he’ll be under inescapable pressure to disclose his findings to Congress and the public.

The FBI director said the question of Russian meddling goes to the core of the democratic system. “It threatens what is America,” he said. That doesn’t sound like something that can be settled with a simple “case closed.”

Besides, this is the same Comey who closed his investigation into Clinton’s emails with an unusual statement that she had been “extremely careless,” even though her conduct didn’t merit prosecution.

“Comey still seems compelled to talk more about his findings than most prosecutors,” Ayer said. “I worry that he may not have learned much from the Clinton debacle.”

Maybe not. Maybe Comey feels an obligation to stick to his Clinton precedent, and to show he’s even-handed after helping Trump win the election (inadvertently, his defenders insist).

Either way, it spells trouble for Trump. The president faces an FBI director who is deeply committed to his investigation, willing to spend as long as it takes, and able to send agents around the world in search of evidence.

If Trump has anything to hide, he’ll regret that he didn’t come clean earlier, when he had the chance. But that wouldn’t be the Trump we’ve come to know, would it?

By Doyle McManus

Doyle McManus is a columnist for the Los Angeles Times. -- Ed.

(Tribune Content Agency)