WASHINGTON — Five years ago, Paul Manafort arranged for a prominent New York-based law firm to draft a report that was used by allies of his client, Viktor Yanukovych, the Russia-aligned president of Ukraine, to justify the jailing of a political rival. And now the report is coming back to haunt it.

The Justice Department, according to two people with direct knowledge of the situation, recently asked the firm, Skadden, Arps, Slate, Meagher & Flom, for information and documents related to its work on behalf of Mr. Yanukovych’s government, which crumbled after he fled to Russia under pressure.

The request comes at a time when Mr. Manafort, his work for Mr. Yanukovych’s party and for Russian and Ukrainian oligarchs as well as the handling of payments for that work have become focal points in the investigation of the special counsel, Robert S. Mueller III, into Russian meddling in the 2016 presidential election, and connections between Russia, Mr. Trump and his associates.

It’s unclear if the Justice Department’s request to Skadden, as the firm is known, is part of Mr. Mueller’s inquiry. But the interest from prosecutors in what Skadden did for the Ukrainian government is one indication of the wide-ranging nature of the inquiries related to Mr. Manafort. It also highlights the risks associated with advising authoritarian governments overseas, a lucrative sideline among Washington lawyers, lobbyists and public relations consultants.