A federal judge ruled that ex-Trump campaign chief Paul Manafort lied to prosecutors.
That means he broke his plea deal with Special Counsel Robert Mueller's team and with that agreement breached, Manafort may now face a long prison term.
The ruling was handed down on Wednesday (February 13).
The judge also said the lies were about topics critical to the Russia investigation.
The special counsel's team and Manafort's lawyers wrangled for weeks over whether he'd delayed the Russia probe by lying.
Robert Mueller and his team are looking into whether Moscow interfered in the 2016 election and possible collusion between Russia and U.S. President Donald Trump's campaign.
The judge on Wednesday found there was evidence to show Manafort meant to lie about three topics, including communication with his former business partner, Konstantin Kilimnik.
Prosecutors say Kilimnik has ties to Russian intelligence.
Mueller says Manafort lied about the number of times he and Kilimnik talked about a 'Ukrainian peace plan,' a proposal that would end in the U.S. lifiting sanctions on Russia.
That's a top goal of the Kremlin.
Russia has denied any collusion and Trump dismisses it as a political witch hunt.
In a separate filing before the ruling, Manafort's lawyers repeated their argument that he corrected any mistakes in his statement once they were pointed out and that Manafort never intentionally lied.