Russian Billionaire Tied to Putin Is Focus of Inquiry A billionaire Russian businessman known to have ties to President Vladimir V. Putin of Russia and a company the businessman controlled have been the focus of a federal investigation into money laundering and oil trading, according to documents and people briefed on the matter. A federal law enforcement official, who like others with knowledge of the case asked not to be named to discuss the inquiry, said Wednesday that "the Justice Department has launched a money-laundering investigation into Gennady Timchenko as part of its initiative to crack down on overseas corruption. The case is being led by federal prosecutors in Brooklyn and F.B.I. agents in New York. The inquiry, first reported by The Wall Street Journal, centers on Gunvor Group, a commodities trading firm whose founders included Mr. Timchenko, the people briefed on the matter said. In March, he sold his share of the company to his Swedish partner. That was a day before the White House added several businessmen with ties to Mr. Putin, including Mr. Timchenko, to a list of those facing sanctions over Russia's incursions into Ukraine. During the investigation, which dates to at least 2011, prosecutors issued subpoenas to American banks, oil trading companies and a Gunvor subsidiary. In a bond prospectus for investors last year, Gunvor Group said that the subsidiary, Castor Americas in Houston, was subpoenaed in 2011 by the United States attorney's office in Brooklyn "for documents relating to Castor's oil trading activities, among other matters." The prospectus said three employees of Castor and one employee of Gunvor were also served. "Gunvor is not aware of the full scope" of the inquiry, the prospectus added. A spokesman for the United States attorney in Brooklyn declined to comment Wednesday night. Efforts to reach Mr. Timchenko or his representatives were unsuccessful.