CNN
Now playing
01:59
How did the Russians allegedly interfere?
WASHINGTON D.C - SEPTEMBER 27: Judge Brett Kavanaugh testifies to the Senate Judiciary Committee during his Supreme Court confirmation hearing in the Dirksen Senate Office Building on Capitol Hill September 27, 2018 in Washington, DC. Kavanaugh was called back to testify about claims by Christine Blasey Ford, who has accused him of sexually assaulting her during a party in 1982 when they were high school students in suburban Maryland.  (Photo by Jim Bourg-Pool/Getty Images)
Pool/Getty Images
WASHINGTON D.C - SEPTEMBER 27: Judge Brett Kavanaugh testifies to the Senate Judiciary Committee during his Supreme Court confirmation hearing in the Dirksen Senate Office Building on Capitol Hill September 27, 2018 in Washington, DC. Kavanaugh was called back to testify about claims by Christine Blasey Ford, who has accused him of sexually assaulting her during a party in 1982 when they were high school students in suburban Maryland. (Photo by Jim Bourg-Pool/Getty Images)
Now playing
02:34
Was Kavanaugh picked to block Mueller probe?
Raskin & Raskin
Now playing
02:45
Trump lawyers quietly driving talks with Mueller
Rod Rosenstein, deputy attorney general, listens during a Senate Judiciary Committee confirmation hearing for Brett Kavanaugh, U.S. Supreme Court associate justice nominee for U.S. President Donald Trump, not pictured, in Washington, D.C., U.S., on Tuesday, Sept. 4, 2018. If confirmed, Kavanaugh would fortify the high court's conservative majority, and spotlight the rightward march of the federal judiciary under Trump and the GOP-controlled Senate. Photographer: Andrew Harrer/Bloomberg via Getty Images
Bloomberg/Bloomberg/Bloomberg via Getty Images
Rod Rosenstein, deputy attorney general, listens during a Senate Judiciary Committee confirmation hearing for Brett Kavanaugh, U.S. Supreme Court associate justice nominee for U.S. President Donald Trump, not pictured, in Washington, D.C., U.S., on Tuesday, Sept. 4, 2018. If confirmed, Kavanaugh would fortify the high court's conservative majority, and spotlight the rightward march of the federal judiciary under Trump and the GOP-controlled Senate. Photographer: Andrew Harrer/Bloomberg via Getty Images
Now playing
01:02
The man who oversees Mueller's investigation
Michael Cohen, President Donald Trumps personal lawyer walks down Park Avenue in New York June 15, 2018 after leaving his hotel. - President Donald Trump's personal attorney Michael Cohen has indicated that he is willing to cooperate with federal investigators to alleviate the pressure on himself and his family. (Photo by TIMOTHY A. CLARY / AFP)        (Photo credit should read TIMOTHY A. CLARY/AFP/Getty Images)
TIMOTHY A. CLARY/AFP/Getty Images
Michael Cohen, President Donald Trumps personal lawyer walks down Park Avenue in New York June 15, 2018 after leaving his hotel. - President Donald Trump's personal attorney Michael Cohen has indicated that he is willing to cooperate with federal investigators to alleviate the pressure on himself and his family. (Photo by TIMOTHY A. CLARY / AFP) (Photo credit should read TIMOTHY A. CLARY/AFP/Getty Images)
Now playing
02:06
ABC: Cohen has done interviews with Mueller
U.S. Deputy Attorney General Rod Rosenstein delivers remarks on "Justice Department Views on Corporate Accountability" during the The Annual Conference for Compliance and Risk Professionals at the Mayflower Hotel May 21, 2018 in Washington, DC. (Chip Somodevilla/Getty Images)
Chip Somodevilla/Getty Images
U.S. Deputy Attorney General Rod Rosenstein delivers remarks on "Justice Department Views on Corporate Accountability" during the The Annual Conference for Compliance and Risk Professionals at the Mayflower Hotel May 21, 2018 in Washington, DC. (Chip Somodevilla/Getty Images)
Now playing
05:41
Rosenstein: 12 Russians charged with hacking
CNN
Now playing
00:48
Trump: I believe Manafort will tell the truth at plea deal
Trump interview with NBC's Lester Holt. May 11 2017
NBC
Trump interview with NBC's Lester Holt. May 11 2017
Now playing
01:12
Sekulow: NBC edited Trump interview on Comey
CNN
Now playing
02:04
Starr: Mueller is getting closer to the truth
NBC
Now playing
01:30
Giuliani: Truth isn't truth
NEW YORK, NY - NOVEMBER 15: Don McGahn, general counsel for the Trump transition team, gets into an elevator in the lobby at Trump Tower, November 15, 2016 in New York City. President-elect Donald Trump is in the process of choosing his presidential cabinet as he transitions from a candidate to the president-elect. (Photo by Drew Angerer/Getty Images)
Drew Angerer/Getty Images North America/Getty Images
NEW YORK, NY - NOVEMBER 15: Don McGahn, general counsel for the Trump transition team, gets into an elevator in the lobby at Trump Tower, November 15, 2016 in New York City. President-elect Donald Trump is in the process of choosing his presidential cabinet as he transitions from a candidate to the president-elect. (Photo by Drew Angerer/Getty Images)
Now playing
03:27
Trump attacks NYT report in morning tweet
NEW YORK, NY - JUNE 9: Don McGahn, lawyer for Donald Trump and his campaign, leaves the Four Seasons Hotel after a meeting with Trump and Republican donors, June 9, 2016 in New York City.
Drew Angerer/Getty Images
NEW YORK, NY - JUNE 9: Don McGahn, lawyer for Donald Trump and his campaign, leaves the Four Seasons Hotel after a meeting with Trump and Republican donors, June 9, 2016 in New York City.
Now playing
02:27
NYT: WH counsel cooperating with Mueller probe
WASHINGTON, DC - JUNE 21:  Special counsel Robert Mueller (2nd L) leaves after a closed meeting with members of the Senate Judiciary Committee June 21, 2017 at the Capitol in Washington, DC. The committee meets with Mueller to discuss the firing of former FBI Director James Comey.  (Photo by Alex Wong/Getty Images)
Alex Wong/Getty Images
WASHINGTON, DC - JUNE 21: Special counsel Robert Mueller (2nd L) leaves after a closed meeting with members of the Senate Judiciary Committee June 21, 2017 at the Capitol in Washington, DC. The committee meets with Mueller to discuss the firing of former FBI Director James Comey. (Photo by Alex Wong/Getty Images)
Now playing
02:07
The Mueller investigation: Who could be next?
Now playing
02:20
Davis describes facing Mueller grand jury
CNN
Now playing
01:36
Analyst: Giuliani doing great harm to Trump
CNN
Now playing
02:00
Roger Stone: I'll never testify against Trump
(CNN) —  

Special counsel Robert Mueller’s office appears to be in an early stalemate in its efforts to bring a criminal case against Russians allegedly involved in Moscow’s efforts to influence the 2016 presidential election.

Although one Russian company indicted by Mueller in February, Concord Management and Consulting, has US attorneys and a court hearing scheduled, the special counsel’s team hasn’t been able to reach the company or its co-defendants.

The Russian government’s top legal office wouldn’t accept paperwork from US law enforcement in the case, and the company has already hit back at Mueller by demanding more evidence and information.

The tit-for-tat was revealed in a court filing Friday when Mueller’s prosecutors asked to reschedule a hearing about the criminal case against 13 Russians and associated companies, who allegedly influenced the election using social media. The hearing was set for May 9.

The situation shows how difficult it will be for Mueller to bring Russians to justice for allegedly interfering in the 2016 election.

The prosecutors said in Friday’s filing that they don’t know whether one of the companies indicted alongside the Russians was served with a summons in the case.

Mueller’s team has tried to reach the Russians, first with the summons delivered to the office of the prosecutor general of Russia on March 20. They have also tried to reach the Russians through the power of international treaties. The Russian law enforcement office declined to accept the summonses, US prosecutors said.

“To the government’s knowledge, no further steps have been taken within Russia to effectuate service,” prosecutors told the judge in DC federal court on Friday.

In US courts, defendants, even those in other countries, must receive formal notice of the charges against them before a case can proceed, unless a judge steps in.

Prosecutors also said US-based defense attorneys for Concord Management and Consulting, from the law firm Reed Smith in Washington, DC, have sought details about evidence Mueller’s office collected in the case.

The Russian company’s attorneys asked for information about other employees who Mueller considered to be co-conspirators or who weren’t charged in the case, the US people who communicated with the Russians, and recordings and other electronic surveillance of the company’s employees.

The company’s attorneys also asked for information about the past seven decades of US policy toward other countries’ elections, especially regarding ” ‘each and every instance’ from ‘1945 to present’ where the US government ‘engaged in operations to interfere with elections and political processes in any foreign country,’ ” according to the prosecutors’ court filing.

The Russian company’s attorneys sent the summons from Mueller’s office back to prosecutors, saying they hadn’t complied with court procedures.

Mueller’s team is asking the Washington judge who oversees the case to weigh arguments about whether Concord properly received notice that it faced an indictment.

The company’s attorneys have not responded to multiple CNN requests for comment since the Russians’ indictments. The judge ordered them to reply to Mueller’s office in court by Monday at 5 p.m.