Counterintelligence is long, hard work. Investigators need time to string along suspects — seeking the who, what, when, where and why of the case. The Federal Bureau of Investigation tries to build 3-D chronologies of who did what to whom. Agents usually follow the money, the best evidence. That’s how the feds got Al Capone: for tax evasion.

The F.B.I. director, James B. Comey, is running the most explosive counterintelligence case since Soviet spies stole the secrets of the atom bomb more than 70 years ago. Some of those atomic spies didn’t speak Russian: They were Americans. We now know that President Vladimir V. Putin of Russia attacked American democracy by meddling in the 2016 election. Did he enlist American mercenaries?

A tantalizing clue came at the House Intelligence Committee hearing on Monday.

First, Democrats named names: the former Trump campaign director, Paul Manafort, dismissed shortly after the F.B.I.’s investigation started in late July; then the former Trump national security adviser, Michael T. Flynn, who lost his job last month. Both appear to have had pecuniary ties to Mr. Putin’s allies — in Mr. Manafort’s case, a politician and an oligarch; in Mr. Flynn’s case, RT, the news and propaganda network.