WASHINGTON — Michael T. Flynn, President Trump’s former national security adviser, was charged and pleaded guilty on Friday to making false statements. Mr. Flynn said he had agreed to cooperate with Robert S. Mueller III, the special counsel, in his broader investigation into Russia’s interference in the 2016 election.

Here are excerpts from court documents and what they mean:

A pile of legal woes yields a single charge

The Special Counsel informs the Court: COUNT ONE (False Statements) On or about January 24, 2017, defendant MICHAEL T. FLYNN did willfully and knowingly make materially false, fictitious, and fraudulent statements and representations in a matter within the jurisdiction of the executive branch of the Government of the United States, to wit, the defendant falsely stated and represented to agents of the Federal Bureau of Investigation, in Washington, D.C., …

Mr. Mueller is charging Mr. Flynn with a single count of lying to the F.B.I. during a Jan. 24 interview, under a plea agreement in which he could serve up to six months in prison and pay a fine of $500 to $9,500. What is most notable here is all the other offenses from which Mr. Flynn escaped charges. Those other potential charges were the leverage that Mr. Mueller successfully used to pressure Mr. Flynn to flip and cooperate in exchange for leniency.

It had been clear for months that Mr. Flynn faced serious legal jeopardy on a range of issues, including work that his lobbying firm performed for Turkey without registering as agents of a foreign power. Earlier this year, Mr. Flynn belatedly filed a Foreign Agents Registration Act disclosure with the Justice Department. But even though Mr. Mueller has obtained an indictment against Paul Manafort Jr., Mr. Trump’s former campaign chairman, in part for violating that same law, he did not charge Mr. Flynn under it.

Moreover, a court filing mentions that Mr. Flynn made several false statements in his belated foreign-agent registration, such as “omitting that officials from the Republic of Turkey provided supervision and direction over the Turkey project.” But Mr. Flynn faced no separate charges based on those lies. Each potential false statement charge could have carried up to five years in prison.