In September, the Department of Justice requested documents from the law firm Skadden Arps Slate Meagher & Flom LLC related to it’s work for the pro-Russian government of Ukraine. It wasn’t clear at the time if the requests were coming from Mueller, or related to some other work being done in the DOJ.
But that indictment of Van Der Zwaan cements the earlier requests to the connection between Yanukovych , Skadden, and Paul Manafort.
On cursory examination, the strong suspicion would be that Paul Manafort is the “Person A” in the indictment, who Van Der Zwaan communicated with, along with Gates in September of 2016. This communication likely involved increased efforts to question Manafort about millions of dollars that may have come to him through under-the-table payments from the pro-Russian party.
It was such allegations that led to Manafort leaving the Trump campaign shortly before the communications with Van Der Zwaan.