Hari Sreenivasan:

For Rick Gates, this day in court was different. He was in Washington, entering the latest guilty plea, the fifth so far in the investigation led by special counsel Robert Mueller.

Gates is a former Trump campaign aide and a longtime associate of Paul Manafort, the former Trump campaign chairman. Today's plea is the result of a deal that Gates cut with Mueller's office.

As part of the agreement, he admitted that he lied to investigators earlier this month, and that he conspired with others to conceal, among other things, his and Manafort's unregistered foreign lobbying. Legal pressure on the two has been mounting of late. Gates and Manafort were indicted last October on 12 counts, including a count related to money laundering.

But just yesterday, a federal grand jury in Virginia piled on a separate indictment against the two, listing 32 total counts, including charges relating to false income tax returns and bank fraud. That said, none of the charges against Gates or Manafort, so far, explicitly deal with Russia's meddling in the 2016 election.

In a statement this afternoon, Manafort said that, even with Gates' plea — quote — "I continue to maintain my innocence."

Meanwhile, at the White House today, President Trump didn't address news of the plea.

Mueller did secure an indictment related to Russia's interference last Friday against a Russian organization called the Internet Research Agency, based in St. Petersburg. And he secured two other guilty pleas in the past week, including one from an attorney, Alex van der Zwaan, who admitted to lying to investigators.

Former Trump National Security Adviser Michael Flynn and former Trump foreign policy adviser George Papadopoulos entered guilty pleas of their own last year.

We explore what today's plea agreement means for the special counsel's investigation with our own Lisa Desjardins, and Carrie Johnson, justice correspondent for NPR.

Lisa, Paul Manafort continues to maintain that he is innocent and he is going to defend himself. Why did Rick Gates plead guilty?