WASHINGTON — When the United States sought to punish Russia last month for its election interference and other aggressions, it targeted some of Russia’s wealthiest men, imposing sanctions on those viewed as enriching themselves off President Vladimir V. Putin’s government.

Now it turns out that one of the men, Viktor F. Vekselberg, was also singled out in another of the efforts to confront Russia’s election interference: the investigation led by the special counsel, Robert S. Mueller III.

Federal agents working with Mr. Mueller stopped Mr. Vekselberg, a billionaire businessman, at a New York-area airport this year, searched his electronic devices and questioned him, according to people familiar with the matter. They confronted him after he stepped off a private plane about two months ago, according to one of the people.

There is no indication that Mr. Mueller suspects Mr. Vekselberg of wrongdoing. But Mr. Vekselberg attended the presidential inauguration last year, and the interest in him suggests that the special counsel has intensified his focus on potential connections between Russian oligarchs and the Trump campaign and inaugural committee.