Maria Butina, the Russian woman charged in federal court last week with acting as an unregistered agent of her government, received financial support from Konstantin Nikolaev, a Russian billionaire with investments in U.S. energy and technology companies, according to a person familiar with testimony she gave Senate investigators.

Butina told the Senate Intelligence Committee in April that Nikolaev provided funding for a gun rights group she represented, according to the person. A spokesman for Nikolaev confirmed that he was in contact with her as she was launching the gun rights group in Russia between 2012 and 2014. He declined to confirm whether Nikolaev gave her financial support.

Nikolaev’s fortune has been built largely through port and railroad investments in Russia. He also sits on the board of American Ethane, a Houston ethane company that was showcased by President Trump at an event in China last year, and is an investor in a Silicon Valley start-up.

Nikolaev has never met Trump, according to his spokesman.

However, Nikolaev’s son Andrey, who is studying in the United States, volunteered in the 2016 campaign in support of Trump’s candidacy, according a person familiar with his activities. Nikolaev was spotted at the Trump International Hotel in Washington during Trump’s inauguration in January 2017, according to two people aware of his presence.

In a court filing last week, prosecutors said Butina’s emails and chat logs are full of references to a billionaire as the “funder” of her activities. They wrote that the billionaire is a “known Russian businessman with deep ties to the Russian Presidential Administration.”

Prosecutors did not identify Butina’s funder by name but said he travels often to the United States and was listed by Forbes this year as having a net worth of $1.2 billion — which is the same as Nikolaev’s current listing.

Butina was ordered held without bond last week after she was charged with conspiring to work as a Russian agent. Prosecutors allege that she sought to meet GOP politicians and infiltrate conservative organizations, including the National Rifle Association, at the direction of a Russian government official, in an attempt to advance the Kremlin’s interests.

According to prosecutors, for two years she traveled back and forth to the United States, often accompanying Russian central banker Alexander Torshin to NRA events and other political meetings. Prosecutors have said her activities were directed by a high-level Russian government official who matches the description of Torshin.

In August 2016, she came to Washington to study full time as a graduate student at American University.

Butina’s lawyer, Robert Driscoll, has said she is not a Russian agent but rather a student interested in learning about the American political system. The Russian government has proclaimed Butina’s innocence, promoting the hashtag #freeMariaButina on social media. Russian Foreign Minister Sergei Lavrov pressed Butina’s case with Secretary of State Mike Pompeo in a phone call Saturday, according to a statement by the Russian government.

Driscoll declined to comment on Nikolaev but said that the Russian businessman cited by prosecutors was a financial supporter of the gun rights group Butina founded in Russia, the Right to Bear Arms. She met him in person only twice, he said.

Prosecutors cited Butina’s interactions with the Russian billionaire to argue she should not be allowed out of jail while awaiting trial. They argued that she has “ties to the Russian oligarchy” and knows wealthy men who could be in a position to offer her “safe harbor” if she decided to flee the United States.

Nikolaev last had contact with the Russian activist in 2014, according to his spokesman, who said that at the time, Butina had a “public profile in Russia as a blogger on key domestic issues that were of interest.”

Nikolaev’s connections to the Russian government “cannot be characterized as deep,” his spokesman said.

“Mr. Nikolaev has no connections to the Russian government other than those that are strictly required professionally,” said the spokesman, who spoke on the condition of anonymity to discuss the ongoing investigation.

He declined to offer details about the political volunteer work by Andrey, Nikolaev’s son.

“Like countless other young people studying in the U.S., Andrey volunteered to hand out leaflets just for the experience,” he said.

Andrey Nikolaev did not respond to a request through the spokesman for comment. Trump campaign officials did not respond to requests for comment.

Konstantin Nikolaev is a major investor in American Ethane and sits on the company’s board.

The company was spotlighted by Trump during a visit to Beijing in November. During the trip, Trump and Chinese President Xi Jinping presided over a ceremony in which U.S. companies publicly signed deals with Chinese partners. One of the 15 deals deal inked at the event was a $26 billion deal for American Ethane to deliver liquid ethane to China.

At the event, Trump and Xi sat on a raised stage and applauded while executives, including American Ethane chief executive John Houghtaling II, came forward to sign trade deals at a table festooned with American and Chinese flags.

The White House declined to comment. Houghtaling declined to comment, except to say that Nikolaev had no role in the China deal or the Beijing ceremony.

Nikolaev has also put money into other U.S. companies. In 2016, he invested in a San Francisco start-up called Grabr, according to a company news release. Grabr operates an online service that allows shoppers to buy unusual products internationally by enlisting the help of ordinary international travelers willing to buy and transport goods for a fee.

Another investor in Grabr, according to the company, is Alexey Repik, a Russian pharmaceutical executive who attended Trump’s inauguration and had access to an array of exclusive events.

Repik said he is a minor investor in Grabr with Nikolaev but that the two are not close. He said he does not know Butina or support pro-gun efforts.

It is unclear if Nikolaev also attended any official inaugural events, but he was seen at Trump’s D.C. hotel, which served as hub of inauguration celebrations. His spokesman declined to comment on what he was doing there.

Also in town for the festivities: Butina, who made an appearance at one of the inaugural balls, according to a person aware of her attendance. Last week, prosecutors submitted as evidence a selfie she snapped in front of the Capitol during the swearing-in ceremony.

Alice Crites, Tom Hamburger, Tom Jackman, Amie Ferris-Rotman and Craig Timberg contributed to this report.