Former Trump campaign manager Paul Manafort leaves the E. Barrett Prettyman U.S. Courthouse after a hearing, May 23, 2018, in Washington, DC. They also come as Trump and his attorney, Rudy Giuliani, have heaped public criticism on the Mueller investigation in an attempt to undermine it.
This has not escaped the attention of Judge T.S. Ellis, who is presiding over Mueller's case against Manafort in a federal court in Alexandria, Virginia.
'They haven't been convicted of anything.
Earlier on Friday, Mr Trump denied that he was considering pardoning Mr Manafort.
In a court filing responding to accusations of witness tampering brought by Mueller on Monday, Manafort's attorneys urged the court to maintain his current conditions of pre-trial release. Manafort has longstanding ties to a pro-Russian political party in Ukraine and a Russian oligarch close to the Kremlin.
They said Kilimnik may have reported to Russian intelligence officers in Moscow or Kiev or both on his work at the International Republican Institute office in Moscow where he was employed for a decade to 2005 and later on his work for Manafort in Ukraine.
Kilimnik is not known to reside in the United States.
Earlier this week Mr Manafort was accused of witness tampering. "Indeed, previously", Manafort said.
On Tuesday he asked that Mr Manafort be detained in jail, claiming that he had been using encrypted communication to try to coach two potential witnesses' testimonies.
Prosecutors said the obstruction charge relates to Mr. Manafort's efforts to coach the stories of witnesses against him.
The White House did not immediately comment on Friday's new charges, but some of Trump's allies quickly picked up a familiar argument.
The two individuals were members of the "Hapsburg group", described by Mueller in the February superseding indictment of Manafort as "a group of former senior European politicians to take positions favorable to Ukraine, including by lobbying in the United States". The work is the basis for the criminal case in Washington where Manafort faces charges of acting as an unregistered foreign agent, money-laundering conspiracy and false statements. So far, 20 people and three companies have been charged. There are four former campaign associates among the indicted - Michael Flynn, Richard Gates, George Papadopoulos and Manafort.
Russian political operative Konstantin Kilimnik was also indicted.
Manafort has acknowledged staying in frequent contact with Kilimnik during the time he worked for Trump's campaign.
The 69-year-old denies all charges against him.
Through a spokesman, Manafort has confirmed the authenticity of the emails but said no briefings occurred.