By MICHAEL ROTHFELD

The husband of a Westchester congresswoman who backed a bill to ban insider trading in Congress has put $350,000 into an investment fund founded by a businessman facing criminal insider-trading charges, according to records and her spouse.

Rep. Nita Lowey, (D., N.Y.) voted Thursday for the Stop Trading on Congressional Knowledge Act, also known as the Stock Act, which passed 417-2 in the House of Representatives and must now be reconciled with a Senate version of the bill. The legislation explicitly prohibits members of Congress from using nonpublic information they receive through their positions for personal benefit.

Ms. Lowey's husband, Stephen Lowey, said in an interview that he invested $350,000 since 2008 in a fund run by New Silk Route Growth Capital. The private equity fund was co-founded by Rajat Gupta, a former Goldman Sachs Group Inc. board member who has pleaded not guilty to criminal insider-trading charges filed late last year.

Mr. Lowey said the investment has nothing to do with congressional insider trading. The investment would not be prohibited by the bill passed Thursday.

"Neither Mrs. Lowey nor I know Mr. Gupta, have ever met him or have had any dealings with him at all," Mr. Lowey said. Of his wife, he said: "It's not her investment. She had nothing to do with it." Ms. Lowey, through a spokesman, declined to comment on the issue and said she wasn't involved with her husband's investments.

Federal prosecutors in Manhattan have accused Mr. Gupta of providing tips about Goldman and other companies to Raj Rajaratnam, a friend who ran the Galleon Group of hedge funds and was convicted at an insider trading-trial in May. Mr. Rajaratnam now is serving an 11-year prison term. Prosecutors called Mr. Rajaratnam a founding partner of New Silk Route.

Mr. Gupta's lawyer has called the charges "totally baseless" and declined to comment Thursday. New Silk Route also declined to comment.

The government hasn't accused New Silk Route of any wrongdoing in Mr. Gupta's case. Prosecutors have said in a criminal indictment that Mr. Gupta provided inside information to Mr. Rajaratnam because of their "friendship and business relationships," including New Silk Route. They said Mr. Gupta benefitted from a $50 million capital commitment Mr. Rajaratnam made to New Silk Route and his assistance in raising capital for the fund. Mr. Gupta's lawyer has said he had no motive to tip the hedge fund founder because they had a falling out, and Mr. Rajaratnam's investment since has been redeemed.

Mr. Gupta, a former head of global consulting firm McKinsey & Co. and chairman of New Silk Route, took a leave from the fund nearly a year ago amid the insider-trading investigation.

Mr. Lowey, a lawyer, said he committed $500,000 in 2008 to New Silk Route, which focuses on investments in India, because he and his wife had a relationship with another New Silk Route co-founder, Parag Saxena, whom he called "a neighbor and a friend" in Westchester County. Mr. Lowey has made several payments building toward that commitment but has not yet met it, he said.

Mr. Saxena also contributed a total of more than $8,000 to Ms. Lowey's congressional campaign funds between 2006 and 2011, public records show. Mr. Saxena could not be reached for comment.

Mr. Lowey made contributions to New Silk Route in 2010, including one after The Wall Street Journal first reported that Mr. Gupta was involved in the federal insider-trading investigation.

Mr. Lowey said all his investments in New Silk Route since 2008 have stemmed from requests for more capital by the fund. He said his investment was down by roughly $30,000 at the end of 2010 but was unsure of its current value. "If there were any smoke here, that's one thing," Mr. Lowey said. "But there's nothing here."

Write to Michael Rothfeld at michael.rothfeld@wsj.com