WASHINGTON — Lawyers for Michael T. Flynn, President Trump’s first national security adviser, asked a federal judge late Tuesday to spare him prison time for misleading investigators, and they suggested that the F.B.I. agents who interviewed him last year at the White House had tricked him into lying.
Mr. Flynn’s lawyers said that his contrition, lengthy military service and willingness to aid the special counsel, Robert S. Mueller III, should warrant a sentence of only probation. “His cooperation was not grudging or delayed,” Mr. Flynn’s lawyers wrote in a sentencing memo that included letters from supporters vouching for his character.
But the lawyers offered no explanation for why Mr. Flynn lied to agents about conversations he had during the presidential transition in late 2016 with the Russian ambassador, Sergey I. Kislyak. And even in accepting blame, Mr. Flynn portrayed himself as a victim of F.B.I. tactics to trap him. His lawyers highlighted details from the interview that played into an unfounded theory that Mr. Flynn’s demeanor during questioning was potential evidence that he did not lie to investigators.
Their emphasis on the F.B.I.’s conduct during the interview aligns with Mr. Trump’s dim view of federal law enforcement. The president has denounced the Russia investigation as a “witch hunt,” and one of his lawyers broached the prospect of a pardon for Mr. Flynn last year as he was weighing whether to cooperate with Mr. Mueller’s investigators.
Mr. Flynn’s lawyers singled out Andrew G. McCabe, the former F.B.I. deputy director, and Peter Strzok, a senior counterintelligence agent who interviewed Mr. Flynn. Both men were fired from the F.B.I. this year, and the president and his allies have attacked them as enemies bent on undermining Mr. Trump. They also have accused Mr. McCabe, Mr. Strzok and other former F.B.I. officials of unfairly targeting Mr. Flynn.
Mr. Flynn’s time in the White House began to unravel days into Mr. Trump’s administration. On Jan. 24, 2017, Mr. McCabe called Mr. Flynn to tell him that Mr. Strzok and another agent would be coming to discuss Mr. Flynn’s communications with Russian officials as part of their investigation into Moscow’s election interference and whether any Trump associates conspired.
Mr. Flynn, a retired Army lieutenant general and the former head of the Defense Intelligence Agency, indicated that he knew that American intelligence had been listening to Mr. Kislyak’s calls, former law enforcement officials have said.
When the agents arrived at the White House, the lawyers wrote, an easygoing Mr. Flynn offered to give them a tour. One agent said Mr. Flynn was “unguarded” and “clearly saw the F.B.I. agents as allies,” the lawyers wrote.
Mr. McCabe and other F.B.I. officials had decided beforehand that the agents “would not warn Flynn that it was a crime to lie during an F.B.I. interview because they wanted Flynn to be relaxed, and they were concerned that giving warning might adversely affect the rapport,” the lawyers wrote, citing internal F.B.I. documents.
Mr. Flynn denied asking Mr. Kislyak that Russia refrain from reacting harshly to sanctions imposed by the Obama administration over Russia’s campaign of disruption and said he did not remember Mr. Kisklyak saying that Moscow had backed off as a result of Mr. Flynn’s request.
Some conservatives have embraced the theory that Mr. Flynn’s nonchalance was exculpatory. But he admitted late last year that he did lie to the F.B.I. when he pleaded guilty.
Mr. Flynn faces up to six months in prison when he is sentenced on Dec. 18, but a punishment of that length seems unlikely. Federal prosecutors also told Judge Emmet G. Sullivan of the United States District Court for the District of Columbia last week that Mr. Flynn deserved little to no prison time. They cited the substantial information he provided in several current federal inquires, including sitting for 19 interviews with Mr. Mueller’s team and other investigators that amounted to more than 60 hours.
Mr. Flynn also “deserves credit for accepting responsibility in a timely fashion and substantially assisting the government,” prosecutors wrote. His decision to plead guilty and cooperate, they wrote, “likely affected the decisions of related firsthand witnesses to be forthcoming.”
Mr. Flynn’s cooperation gave the special counsel a source of information about how Mr. Trump and his advisers responded in the months after his surprise election victory and from inside the Oval Office during the administration’s chaotic first weeks.
In addition to the sanctions, Mr. Flynn and Mr. Kislyak also discussed a coming United Nations Security Council vote on whether to condemn Israel’s building of settlements. Prime Minister Benjamin Netanyahu of Israel asked the Trump transition team to press other countries to help Israel, prosecutors have said.
Because Mr. Flynn was untruthful with the F.B.I. about those discussions, senior law enforcement officials warned the White House that he could be at risk of being blackmailed by Russia. Mr. Trump and his aides reviewed the situation and concluded that Mr. Flynn had no legal exposure. But he was fired after only 24 days when the conversations became public, and aides said he had misled Vice President Mike Pence about the calls.
In his plea agreement, prosecutors said Mr. Flynn’s lies and omissions hurt the Russia investigation.
Mr. Flynn had a decorated career in the Army, rising to become head of the Defense Intelligence Agency before President Barack Obama fired him in 2014 over management failures.
Mr. Flynn went on to create his own consulting company. Among his clients was the government of Turkey, which paid him more than a half-million dollars to investigate Fethullah Gulen, a Turkish cleric who lives in Pennsylvania.
President Recep Tayyip Erdogan of Turkey has held Mr. Gulen and his supporters responsible for a failed coup attempt in 2016 and has repeatedly demanded that the United States extradite Mr. Gulen, who fled Turkey in 1999.
Mr. Flynn has admitted that he failed to properly register as an agent of Turkey, and federal prosecutors in Virginia are investigating the secret Turkish lobbying effort that once ensnared him.
Mr. Trump has said Mr. Flynn had to leave the White House after deceiving Mr. Pence, but the president has defended his former national security adviser, saying investigators treated him unfairly.
Mr. Flynn has also figured into the special counsel’s investigation into whether the president obstructed justice. James B. Comey, the former F.B.I. director, has told lawmakers that the president asked him to shut down the F.B.I. investigation into Mr. Flynn.
Asked last week about Mr. Flynn’s case, Mr. Comey said he was glad Mr. Flynn was “held accountable for his crimes and that he was assisting the United States. So it seemed to me like a just outcome.”
Mr. Comey also dismissed the theory about Mr. Flynn’s body language.
“The conclusion of the investigators was he was obviously lying,” Mr. Comey said, “but they saw none of the normal common indicia of deception: that is, hesitancy to answer, shifting in seat, sweating, all the things that you might associate with someone who is conscious and manifesting that they are being — they’re telling falsehoods.”