When American prosecutors accused a senior Russian official’s son of laundering $14 million by investing in Manhattan property and other assets, she was called to defend him. When Moscow regional officials battled Ikea over the Swedish retailer’s expansion, she took on their case.

Natalia Veselnitskaya, the Russian lawyer who met with Donald Trump Jr. last year to discuss possible compromising material on the Democrats, has been widely depicted as a one-issue activist consumed with getting Congress to repeal sanctions against Russian businessmen.

But lawyers and others in Moscow’s legal community called her a trusted insider, one who could be counted on to argue and win important high-profile court cases that matter to the government and to one senior, well-connected official in particular.

Ms. Veselnitskaya, 42, earned her status as the go-to lawyer for the Moscow regional government. For years, she has been a lawyer for the Katsyv family, whose patriarch, Pyotr D. Katsyv, was minister of transportation of the Moscow region for more than a decade, and whose son was caught up in the New York money laundering case.

The elder Mr. Katsyv is now a vice president of Russian Railways, a state-owned railroad monopoly that is the country’s largest employer and one long dogged by corruption allegations.

A spokesman for Rohrabacher told BuzzFeed News that while he didn't invite Veselnitskaya to the hearing, he was introduced to her the next day when she appeared at the Capitol Hill Club — a private social club for Republicans — for dinner.

Rohrabacher initially told BuzzFeed News on Thursday that his staff didn't invite her either. When asked how she ended up at the hearing, he said, “Well, she heard about it, and she wanted to come... these are open hearings.”

When asked again if he or his staff had extended the invitation, he said, “Not that I know of. I don’t know of anything. I wouldn’t have recognized her, and, uh, you know, I don’t know her."

He added, "I know she was at a dinner table that, where there were 20 people, and this is over at the Capitol Hill Club, it might have been the night of that thing, and she was at the table, at least that’s what I’m told. I wouldn’t even know her if I saw her.”