A quick internet search reveals Ms. Veselnitskaya as a formidable operator with a history of pushing the Kremlin’s agenda. Most notable is her campaign against the Magnitsky Act, which provoked a Cold War-style, tit-for-tat row with the Kremlin when President Barack Obama signed it into law in 2012.
Under the law, some 44 Russian citizens have been put on a list that allows the United States to seize their American assets and deny them visas. The United States asserts that many of them are connected to fraud exposed by Mr. Magnitsky, who after being jailed for more than a year was found dead in his cell. A Russian human rights panel found that he had been assaulted. To critics of Mr. Putin, Mr. Magnitsky, in death, became a symbol of corruption and brutality in the Russian state.
An infuriated Mr. Putin has called the law an “outrageous act,” and, in addition to banning American adoptions, compiled what became known as an “anti-Magnitsky” blacklist of United States citizens.
Among those blacklisted was Preet Bharara, then the United States attorney in Manhattan, who led high-profile convictions of Russian arms and drug dealers. Mr. Bharara was abruptly fired in March, after previously being asked to stay on by Mr. Trump.
One of Ms. Veselnitskaya’s clients is Denis Katsyv, the Russian owner of a Cyprus-based investment company called Prevezon Holdings. He is the son of Petr Katsyv, the vice president of the state-owned Russian Railways and a former deputy governor of the Moscow region. In a civil forfeiture case prosecuted by Mr. Bharara’s office, the Justice Department alleged that Prevezon had helped launder money tied to a $230 million corruption scheme exposed by Mr. Magnitsky by parking it in New York real estate and bank accounts. As a result, the government froze $14 million of its assets. Prevezon recently settled the case for $6 million without admitting wrongdoing.
Ms. Veselnitskaya and her client hired a team of political and legal operatives that has worked unsuccessfully in Washington to repeal the Magnitsky Act. They also tried but failed to keep Mr. Magnitsky’s name off a new law that takes aim at human-rights abusers across the globe.
Besides the private investigator whose firm produced the Trump dossier, the lobbying team included Rinat Akhmetshin, an émigré to the United States who once served as a Soviet military officer and who has been called a Russian political gun for hire.
Ms. Veselnitskaya was also deeply involved in the making of an anti-Magnitsky film that premiered just weeks before the Trump Tower meeting. Titled “The Magnitsky Act — Behind the Scenes,” the film echoes the Kremlin line that the widely accepted version of Mr. Magnitsky’s life and death is wrong. The film claims that he was not assaulted and alleges that he never testified that government officials conspired to steal $230 million in fraudulent tax rebates.
In the film’s telling, the true culprit of the fraud was William F. Browder, an American-born financier who hired Mr. Magnitsky to investigate the fraud after he had three of his investment funds companies in Russia seized. On RussiaTV5, a station whose owners are known to be close to Mr. Putin, Ms. Veselnitskaya was lauded as “one of those who gave the film crew the real proofs and records of testimony.”
Mr. Browder, who stopped the screening of the film in Europe by threatening libel suits, called the film a state-sponsored smear campaign.
“She’s not just some private lawyer,” Mr. Browder said of Ms. Veselnitskaya. “She is a tool of the Russian government.”