Concord Management and Consulting on Wednesday pleaded not guilty to a charge brought by special counsel Robert Mueller that the company was party to a conspiracy to defraud the United States.

Concord is one of three Russian companies and 13 Russians indicted in February by Mueller on charges stemming from interference in the 2016 presidential election using social media. The company, which was represented in federal court by attorney Eric Dubelier, is the only defendant that has yet to appear in court.

When indicted, none of the Russians were in U.S. custody and it is unlikely they ever will be. Mueller’s prosecutors said in a court filing last week that Russia’s prosecutor general has declined to serve the defendants with a summons, and Russia does not allow extradition of its citizens to Russia.

“Alas, they are not here,” said Jeannie Rhee, a veteran trial attorney who joined Mueller’s team last July. She is also a former deputy assistant attorney general at the Department of Justice.

Rhee told U.S. Magistrate Judge G. Michael Harvey that it is likely the federal government will need new summonses against the other two Russian companies charged: Concord Catering, a company owned by Concord Management and Consulting, and the Internet Research Agency.

Concord Catering is run by Yevgeniy Viktorovich Prigozhin, a Russian businessman known as “Putin’s chef” because of his close relationship to Russian President Vladimir Putin. He is also a Russian oligarch who is an alleged financial backer of IRA, the famous Russian troll farm.

Dubelier told the judge Wednesday that the special counsel’s office has obtained Concord Management’s “confidential files” within the U.S. Department of Treasury’s Office of of Foreign Assets Control.

He called this “disturbing” but declined to elaborate what he meant to reporters after the arraignment.

Dubelier, who represents Concord Management alongside Kate Seikaly, also said his client had not been “properly served" by Mueller's office.

In a court filing Saturday, Concord Management’s lawyers again argued that the summons had not been properly served and criticized Mueller’s team for moving to have arraignment moved because they would not be physically present.

“Defendant voluntarily appeared through counsel as provided for […] and further intends to enter a plea of not guilty. Defendant has not sought a limited appearance nor has it moved to quash the summons. As such, the briefing sought by the Special Counsel’s motion is pettifoggery,” wrote Dubelier and Seikaly.

Judge Harvey set a status hearing to determine if a new summons is necessary for May 16.