Four years before the 2016 campaign, van der Zwaan had worked with Manafort for Russian-backed political groups in Ukraine - the office of Special Counsel Robert Mueller has charged that Manafort hid millions of dollars in profits related to that and other work.
In his guilty plea, van der Zwaan admitted that he lied repeatedly to investigators, and also "withheld and otherwise destroyed documents requested by the Special Counsel's Office," including a specific 2016 email in Russian.
In court documents, Mueller’s team said “van der Zwaan is in an unusual position of having information related to the Office’s investigation that is not widely known," possibly tied to contacts between top Manafort aide Rick Gates and someone with links to Russian intelligence; those communications allegedly took place in September and October of 2016.
It's not clear what that information pertains to in the Russia investigation, and whether it has any ties to the 2016 campaign; Mueller's office has asked the judge to keep the evidence under wraps.
Lawyers for van der Zwaan argued against jail time, citing the fact that his wife is going through a difficult pregnancy in London.
Van der Zwaan's father-in-law is German Khan, often described as a Russian oligarch. Named in the Steele Dossier, Khan is one of three Russians who have sued BuzzFeed over publication of that opposition research done on Mr. Trump during the 2016 campaign, bankrolled by a law firm with direct ties to the Democratic Party.
The van der Zwaan sentencing came a day after the Special Counsel's office defended the scope of the investigation into possible financial wrongdoing by Manafort and his top aide Gates, who has already pleaded guilty to lying to investigators, and is cooperating with the Special Counsel's probe.
In a document filed on Monday in Manafort's case, Mueller's team specifically says that Deputy Attorney General Rod Rosenstein authorized the investigation into allegations that Manafort, "Committed a crime or crimes by colluding with Russian government officials," to interfere in the 2016 elections.
The document cited a previously classified memo from Rosenstein, written on August 2, 2017 - a redacted copy was included in Monday's court filing, with most of the allegations related to the Russia probe blacked out - except for the portions related to Manafort.