Kilimnik has always been a close business colleague of Manafort's that prosecutors have said in previous filings has ties to Russian intelligence.
Manafort has already been charged with conspiracy against the United States, conspiracy to launder money, unregistered agent of a foreign principal, false and misleading Foreign Agents Registration Act statements and false statements.
Besides the president or his family, there is perhaps no bigger fish in the Russian Federation investigation than Manafort.
Manafort and Kilimnik's allegedly criminal contact with the two witnesses who once worked with them doing public relations began on a day, February 23, when Manafort's case became far tougher to overcome.
The new charges were unsealed Friday against Paul Manafort and Konstantin Kilimnik. In a previous indictment, Mueller's team said Kilimnik-named as "Person A"-was a former officer of the Russia's military intelligence wing, the GRU".
Court documents say Manafort and an associate, identified as "Person A", reached out to two witnesses, identified as "Person D1" and "Person D2".
Because as Renato and I detailed in our piece yesterday, for bail purposes the judge must only determine by the relatively low probable cause standard that Manafort attempted to tamper with witnesses.
The witnesses that Kilimnik and Manafort approached were involved in Manafort's alleged lobbying campaign on behalf of Ukrainian's government.
As Law&Crimepreviously reported, Mueller's prosecutors were upfront with Manafort at the start that they planned to indict him, an apparent tactic to shock him into "flipping" or airing dirty laundry.
Earlier on Friday, Mr Trump denied that he was considering pardoning Mr Manafort.
Kilimnik, also a political consultant, specifically helped Manafort and Gates in their effort to elect Party of Regions candidate Viktor Yanukovych to Ukraine's presidency and to help him lobby the U.S between 2006 and 2014.