Skadden, Arps, Slate, Meagher & Flom’s controversial work for the former government of Ukraine is part of an investigation by the Justice Department, which is asking the firm to produce documents on its work, according to a report by The New York Times on Thursday.

Skadden’s work was already under public scrutiny from several media reports in the last year. Skadden was paid more than $1 million in legal fees after putting together a December 2012 report that critics said effectively justified the jailing of a Ukrainian political rival, former Ukrainian Prime Minister Yulia Tymoshenko, according to media reports.