Updated at 1:27 p.m. ET

In a surprise development, a lawyer who worked at the firm that produced a report for Paul Manafort’s Ukrainian lobbying campaign has been charged with lying to Special Counsel Robert Mueller’s team. The charges were revealed in court documents filed on Friday that became public on Tuesday.

The lawyer, Alex Van Der Zwaan “willfully and knowingly” made “materially false, fictitious, and fraudulent statements and representations” to the investigators about his conversations with Manafort deputy Rick Gates and an unnamed third person, prosecutors alleged in the new court filings.

A plea agreement hearing is schedule for 2:30 p.m. ET in federal court in Washington, D.C., where Van Der Zwaan is expected to plead guilty.

Zwaan —who according to the Kyiv Post is based in London and is the son-in-law of Russian oligarch German Khan — spoke to investigators on Nov. 3, just a few days after Mueller’s indictments against Manafort and Gates became public, the court documents said. Before Tuesday’s revelation, Zwaan’s name has come up only peripherally in connection with the Manafort-Gates case.

Gates and Manafort have both been charged by Mueller for failure to disclose the Ukrainian lobbying work, among other things. They have both pleaded not guilty.

Zwaan’s firm’s Skadden Arps Slate Meagher & Flom LLC was behind a 2012 report that sought to justify the Ukrainian government’s prosecution and conviction of Yulia Tymoshenko, the former prime minister of Ukraine. Manafort, who went on to serve as President Trump’s campaign chairman, recruited the firm to produce the report while he was advising Viktor Yanukovych, a pro-Russian Ukrainian politician.

It was reported in September that Mueller was interested in Skadden’s involvement in the report. “The firm terminated its employment of Alex van der Zwaan in 2017 and has been cooperating with authorities in connection with this matter,” Skadden said in a statement released Tuesday.

Zwaan allegedly told investigators he last spoke to Gates in August 2016, when he in fact spoke to Gates a month later, prosecutors said in the filings. The September conversations also involved a person dubbed by Mueller as “Person A,” according to the court documents. Zwaan “surreptitiously recorded” the phone calls, the prosecutors alleged.

Zwaan allegedly also misled investigators about a September 2016 email between him and “Person A,” according to the court documents. He allegedly told investigators he did not know why the email was not produced for Mueller’s team, the court document said. Prosecutors alleged that Zwaan deleted and otherwise did not produce that and other emails.

Read the filing below: