(CNN)The special counsel investigation into Russian interference in the 2016 election revealed Tuesday night that prosecutors say they have connected former Trump deputy campaign chairman Rick Gates to a person with ties to a Russian intelligence service while Gates worked on the campaign.

That Gates and the unnamed person, who had lived in Kiev and Moscow and worked for one of Paul Manafort’s companies, were in touch in September and October 2016 was “pertinent to the investigation,” a court filing from prosecutors said Tuesday night.

The acknowledgment that Gates knew the person had Russian intelligence ties is alleged in a report prosecutors filed about the coming sentencing of a Dutch attorney. That attorney, Alex van der Zwaan, who worked with Gates and Manafort previously, pleaded guilty last month to lying to special counsel Robert Mueller’s investigators about his interactions with Gates and the unnamed person.

In an opposing 30-page memorandum also filed Tuesday evening, van der Zwaan begged for leniency and asked the judge to avoid sending him to jail next week. Instead, van der Zwaan asks to pay an “appropriate fine,” according to the filing.

He will be the first defendant in Mueller’s probe to face sentencing, on April 3.

“(H)is world has collapsed as a result of his decision to lie to law enforcement,” the court filing from the Dutch lawyer begins.

Van der Zwaan’s career as a lawyer may be over, and he risks missing the birth of his first child in London, it continues.

“Although he has had occasional visitors and took a car trip with his wife over the Christmas holiday, his existence has largely been solitary. He lives alone in a hotel in a city where he has no close friends. His days are empty and lonely,” van der Zwaan’s filing later states.

Van der Zwaan’s charge carries a maximum sentence of five years in prison, though he qualifies for a recommended sentence of zero to six months. He also faces a fine of up to $250,000.

The prosecutors, in their own memo to federal Judge Amy Berman Jackson Tuesday night, do not ask for any particular sentence, but note how van der Zwaan was an experienced lawyer and lied to them after Manafort and Gates were indicted.

Van der Zwaan’s memo Tuesday describes the work he did at the law firm Skadden Arps, which eventually led to his guilty plea. After years of working with Gates on a report…