Transcript for General Michael Flynn pleads guilty to lying to FBI

We begin with Micha Flynn and his guilty plea. President trump's former national security adviser admitting he lied to the FBI. Arriving with his wife at federal court in Washington already processed and fingerprinted as part of his plea. With the deal, Flynn is now agreeing to cooperate with the special counsel. Could that mean Flynn will testify against the president? We begin with Brian Ross. Reporter: He was one of the president's closest advisers, one of his first major appointments, but today as general Michael Flynn walked out of court in Washington, protesters chanted, lock him up. Lock him up. Reporter: An echo of Flynn's own words about Hillary Clinton. Lock her up. Reporter: Flynn pleaded guilty today to lying to the FBI, telling associates he is prepared to testify, if needed, against president trump and others in the white house. How many more figures have to be brought to justice because of their ties with Russia before we end up connecting all these dots? Reporter: Flynn now admits he lied about his conversations with the Russian ambassador sergey kislyak during the transition period. The white house had claimed it was unaware of the substance of those conversations but today's court documents show Flynn says he was acting with the knowledge of transition team officials. On the same day president trump proposed tough sanctions. The Russian ambassador contacted Flynn. Flynn consulted with a senior transition team official who said the trump team did not want Russia to escalate the situation. A request Flynn are made to the ambassador. President trump tweeted great move by Vladimir Putin. I always knew he was very smart. The documents show that a very senior official on the transition team told Flynn to contact the Russian ambassador about a U.N. Resolution involving Israel. We are learning that senior official was the president Eason in law, Jared Kushner. The president has insisted he did not tell Flynn to make the contacts with Russia. I didn't direct him. But I would have if he didn't do it. Okay. Reporter: According to a confident of Flynn's he is prepared to testify that trump contacted the Russians during the transition as a way to work together against ISIS. It's at odds with what he has been saying publicly from day one. The plea documents suggest that Mueller's investigation may be focused on president trump's firing of FBI director James Comey. Flynn lied to the FBI on January 24th. On January 26th acting attorney general Sally Yates told the white house he had lied. January 27th the president invited the FBI director to a private dinner. The dinner was an effort to build a relationship. In fact, he asked specifically of loyalty in the context of asking me to stay. Reporter: Two weeks later Flynn was fired and Comey says the president later asked him to go easy on the general. I understood him to be saying was drop any investigation connected to Flynn's account of his conversations with the Russians. Reporter: Even after Flynn was gone, the president still praised him. General Flynn is a wonderful man. I think it's a sad thing that he was treated so badly. Reporter: And David, a clarification on something one of Flynn's confident's told us. He said the president asked Flynn to contact Russia during the campaign and now saying according to Flynn candidate trump asked him during the campaign the fine ways to repair relations with Russia and after the election the president-elect told him to contact Russia on other issues including fighting ISIS. We do have a statement from Michael Flynn. He said I accept full responsibility for my actions. That's right. Flynn's confident says he was going broke with crippling legal fees and made this deal for his family. His son, Michael junior had also

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