For the past two weeks, Biden administration officials were confident that they had finally secured a deal to release more than a dozen journalists, pro-democracy activists and wrongfully detained Americans from Russian prisons.

The negotiations had been painstaking and sometimes faltering. But now, sixteen people were on the verge of freedom, among them Wall Street Journal reporter Evan Gershkovich, serving a harsh sentence on baseless accusations of spying; Washington Post contributor Vladimir Kara-Murza, among the most outspoken and trenchant critics of Russian President Vladimir Putin; and Paul Whelan, a former Marine who had languished in Russian prisons for more than five years on trumped-up charges.

Officials in Washington who had helped craft the deal were buoyant as the Americans boarded a plane in Moscow, joined by a group of jailed Russian pro-democracy activists who would travel on to Germany. But until they touched down at an airport in Ankara, Turkey, and their heads were counted, their identities were verified, and they were physically out of Russian custody, U.S. officials kept their fingers crossed and remained, as several recalled, “on pins and needles.”

There was still a lot that could go wrong. During the flight, a European official informed a reporter that a plane bound from Moscow to Ankara had turned back, prompting fears that the deal had been scotched. It turned out to be a false alarm, but it underscored the thrumming anxiety that never abated until the planes carrying the freed prisoners were wheels up.

In the weeks preceding the exchange, painstaking negotiations had to share time with high-stakes politics. On July 21, President Joe Biden got on the phone with the prime minister of Slovenia to make sure he was still willing to release a Russian couple that had been convicted on spying charges, part of the group of prisoners the U.S. and its allies had agreed to offer in the exchange.

One hour after they hung up, Biden, who had been under intense pressure to drop out of the presidential campaign since delivering a halting performance in a debate the previous month, announced publicly that he would not seek reelection in November and became a lame-duck president.

Administration officials had seen proposed prisoners swaps come together, only to disintegrate — once when the key figure in the deal died suddenly in a Russian prison. They had tried to free several Americans at a time, only to settle for one. Cabinet officials, and Biden himself, had previously called family members to discuss their loved ones who weren’t coming home.

The administration always promised to keep working. But few could have imagined the scope of the exchange that took place on Thursday. In all, 16 Americans, Russians and Germans were freed from Russia, in exchange for eight Russians held in the United States, Germany and other countries, including a notorious intelligence operative who gunned down a man in broad daylight in Berlin.

“Not since the Cold War has there been a similar number of individuals exchanged in this way and there has never, so far as we know, been an exchange involving so many countries,” Jake Sullivan, the White House national security adviser, told reporters as planes converged in Turkey. Sullivan had been a key architect of the deal, officials said, and sometimes seemed to be one of the few in the White House who held out any hope it was possible.

This account of how the Biden administration, in what turned out to be its final months, pulled off the biggest prisoner swap in recent history, securing the release of prisoners held by a hostile foreign power engaged in a grinding, bloody war against a U.S. ally, is based on interviews with eight officials in the United States and Europe with knowledge of the negotiations.

Many of the officials involved spoke on the condition of anonymity to recall private conversations and sensitive diplomacy that remain controversial and are sure to draw fire from the president’s critics and others who worry that swapping genuine criminals for people who did nothing wrong or committed comparatively minor offenses, creates a moral hazard that will encourage Russia to seize more innocent people.

In remarks from the White House after the flights had left Turkey, Biden praised the U.S. allies who participated in the deal, including Norway, Poland and Estonia, who had agreed to release Russians in their custody or had extradited criminals to the United States. The deal, he said, had come with “tough calls” and noted there had been no guarantees.

“But there’s nothing that matters more to me,” he said, “than protecting Americans at home and abroad.”

In the end, the linchpin of the deal was not a prominent American journalist or a democratic freedom fighter, but a convicted Russian hit man: Vadim Krasikov.

In 2019, acting on behalf of a Russian intelligence agency, Krasikov gunned down a former Chechen fighter at point-blank range in Berlin’s Kleiner Tiergarten park. A German court sentenced Krasikov to life in prison and condemned the murder as “state terrorism.”

Putin had called the victim, Zelimkhan Khangoshvili, a “bloodthirsty” killer who had attacked Russia. And he praised Krasikov as a patriot. Putin became singularly focused on freeing him from Germany, evincing a kind of obsession with his case that remains puzzling to U.S. officials, who said they still aren’t entirely sure why the Russian president wanted Krasikov freed so badly.

The Russians had earlier raised him as a possible trade item in the fall of 2022, when the United States was working to free Whelan as well as basketball star Brittney Griner, who had been arrested in Russia while carrying a small amount of cannabis oil. At the time, the proposal seemed dead on arrival. Krasikov was in German custody, so he wasn’t Washington’s to give.

Sullivan, the national security adviser, flagged the Russian proposal to his German counterpart, but U.S. officials considered Russia’s idea to be “unserious,” a senior administration official said. Freeing Krasikov would also be an enormously controversial move for German Chancellor Olaf Scholz, who had only been in power for one week when Krasikov was convicted.

Germany also worried about establishing a terrible precedent that would induce Russia to keep taking prisoners. “What do you do when that becomes a business model?” said one senior German official involved in the negotiations.

In December 2022, Russia released Griner in exchange for Viktor Bout, a notorious arms merchant serving a 25-year sentence in a U.S. prison. That deal drew fire from critics, as well as some U.S. officials, who said it violated a long-standing policy of “like for like” in prisoner exchanges. Bout was a hardened criminal dubbed “the Merchant of Death.” Griner was an athlete arrested on what most U.S. courts would consider a minor drug offense. Now it was the turn of U.S. officials, particularly in the Justice Department, to worry that such uneven exchanges would only compel the Russians to seize other high-profile Americans, as well as ordinary citizens, knowing that Washington would bargain for them.

“He was an arms dealer. His contributions to human suffering were tangible and physical. The notion that he was anywhere on par with an innocent basketball player — there was just absolutely no parity on that,” one former department official said.

Moscow also saw Whelan in a separate category from Griner. He had been convicted of espionage and sentenced to 16 years hard labor. Russia had never presented any concrete evidence of Whelan’s crimes, but they believed — and still do, U.S. officials have said — that he was a spy. And spies are traditionally swapped for other spies.

“We had been working for some time to get Whelan out and couldn’t get the Russians to deal because we didn’t have anyone to give that they wanted,” said a U.S. official familiar with the negotiation. “They wanted Krasikov, but the Germans wouldn’t give him just to get Americans back.”

Griner went free, but Whelan, who U.S. officials insisted was no spy, remained in Russia.

With negotiations over Krasikov at an impasse, Secretary of State Antony Blinken started discussing with colleagues who the Germans might want freed from Russia, the U.S. official said. That could induce Berlin to bargain over the convicted assassin.

Eventually, State Department officials came up with a true boldfaced name: Alexei Navalny, Putin’s most famous antagonist and the face of the struggling pro-democracy movement in Russia, then serving time on charges he denounced as politically motivated.

“It was just an internal discussion point with others in the administration,” the official said. But then, in March 2023, Russia arrested Gershkovich, the Wall Street Journal reporter, while he was working in the city of Yekaterinburg. Suddenly the idea of trading for Navalny had new life, and the prisoner negotiations took on a new urgency.

Biden was told the next day about Gershkovich’s arrest during his regular daily intelligence briefing, the senior administration official said. He instructed Sullivan to use diplomatic as well as intelligence channels to come up with a deal for his freedom.

Blinken called his Russian counterpart, Foreign Minister Sergei Lavrov, to protest Gershkovich’s detention. “He is a journalist who works for an internationally respected news outlet,” Blinken said, according to the U.S. official. “Claims that he was spying are outrageous and false.”

“Your government has crossed a line,” Blinken told the Russian, the official said.

Lavrov responded by saying Gershkovich was “caught red-handed” and said “being a journalist does not provide him immunity.” Russia insisted the reporter was spying.

“We are both adults,” Blinken responded. “You know that for all our efforts to learn information, we do not use journalists.”

In April 2023, after Gershkovich had been detained for a month, Blinken and Sullivan again raised the possible trade of Krasikov with their German counterparts. They spoke on the phone and began swapping hard-copy lists of names that could possibly be part of a deal, the senior administration official said. Eventually, the administration raised the issue to the level of the chancellor’s office.

The following year, the negotiations entered a productive stretch. On Jan. 16, Biden invited Scholz to the White House, in large part to discuss the contours of a prisoner swap. Sullivan spoke with his counterpart, Jens Ploetner, on Feb. 2 and received an indication that the United States and Germany could find a joint approach on Krasikov — as long as Navalny was part of the deal. Biden and Scholz met in person at the White House on Feb. 9, as Germany was still working out details of a deal and how the two countries would extend an offer to Russia.

“For you, I will do this,” the German leader told the U.S. president.

But on Feb. 16 came stunning news that took the winds out of the White House’s sails. Navalny had died in a remote Arctic prison. Biden delivered a fiery speech from the White House that day and strongly condemned “Putin’s brutality.” U.S. officials remain unclear on how Navlany died but have noted he was held in extremely harsh conditions. Many of his supporters insist he must have been killed on Putin’s orders.

In Munich, at an annual security conference, world leaders absorbed the news of Navalny’s death, and administration officials sought to keep a prisoner deal together. Vice President Kamala Harris met with Slovenian Prime Minister Robert Golob on the sidelines of the summit to ensure his country was still willing to do its part in the complicated swap by adding the Russian couple convicted of espionage to the mix, the senior administration official said.

She also met with Scholz to discuss the release of Krasikov, according to a second administration official.

But Germany was once again cooling to the idea of swapping for Krasikov. Germany had shown it was willing to give up Krasikov for the right deal. Now the United States had to find it.

Sullivan and the White House team that had been working on a deal went back to the drawing board.

For the next several weeks, the Germans appeared uninterested. U.S. officials gave them space, until Sullivan again spoke with Ploetner at the end of March, the senior administration official said. Ploetner indicated the Germans were not yet ready to move forward. But Sullivan instructed a team to begin generating a list of political prisoners associated with Navalny who were currently held in Russia. They couldn’t free Navalny, but they might be able to bring out his lieutenants.

At the end of March, Biden sent a letter to Scholz laying out the contours of a proposed deal and said the United States had the commitment of the other countries, including Slovenia, Norway and Poland, which would release Russian prisoners to make it happen.

At home, polls showed Biden was losing ground in his campaign for reelection. His opponent, Republican Donald Trump, was mockingly insisting that only he would be able to make a deal with Putin to bring home the Wall Street Journal reporter. On May 23, Trump posted to social media that Gershkovich would be released “almost immediately after the Election” — if he won.

“Vladimir Putin, President of Russia, will do that for me, but not for anyone else, and WE WILL BE PAYING NOTHING!” Trump wrote.

Meanwhile at the Kremlin, officials were still keen to win Krasikov’s release from Germany and, when approached, signaled they were looking for ways to make it happen, according to a Russian familiar with the process. That person said he helped draw up a list of names of Russians held abroad that was presented to Germany, and then, in turn, to Russia’s presidential administration. Officials agreed in principle, he said.

The suggestions didn’t represent the final list of prisoners who were freed, but it showed that Kremlin officials felt they needed to extract a significant number from the West, this person said. “The Kremlin was ready to hand over a lot for Krasikov but didn’t want to make it look like they were ready to give a lot for him,” the person said.

“Putin … only had Krasikov in his head,” he said.

By the beginning of June, the momentum of the secret negotiations was starting to build. The United States received approval from Germany on its side of the deal. At the end of the month, Washington extended the offer to Russia.

Throughout the negotiations, the United States used a special channel set up between the CIA and Russian intelligence to discuss the various prisoner proposals. On June 25, U.S. and Russian officials held a meeting in a third country, said a U.S. official familiar with the matter. The meeting unfolded as Biden huddled with aides, prepping for his debate with Trump.

In early July, CIA Director William J. Burns spoke to one of his Russian counterparts and learned that, in principle, Moscow had agreed to a deal.

“At that point, we were off to the races,” the official said.

On July 19, a Russian court found Gershkovich guilty of spying and sentenced him to 16 years in a high-security penal colony. While the sentence was crushingly long, it was actually a positive signal, since Russia has traditionally sentenced people prior to their release. That same day, a court convicted Alsu Kurmasheva, a Russian American journalist for U.S. Radio Free Europe/Radio Liberty. She too would become one of those freed in the final exchange.

With the perfunctory verdicts handed down, officials in Washington were hopeful the deal would finally materialize. But the last stretch was not without snags. On July 21, Biden, recovering from COVID at his beach house in Rehoboth Beach, Delaware, called the Slovenian prime minister and reaffirmed his commitment to the deal, possibly Biden’s last official act as a declared candidate for president.

Not all the Americans held in Russia came home. Perhaps most prominent among them is Mark Fogel, a teacher who had spent 27 years working overseas. He was arrested at the Moscow airport in August 2021 and charged with smuggling a small quantity of cannabis — prescribed in the United States for back pain but banned in Russia. He was given a 14-year jail term and has been teaching English to prisoners. U.S. officials have promised to continue working for his release.

In the 48 hours before the freed Americans were on their way home, Sullivan called their families and extended an invitation to the White House. At the start of a press briefing on Thursday, Sullivan remarked on how much time he had spent with the families. “Most of the time those are tough conversations,” he said.

“Not today,” he added, fighting back tears, his voice halting. Sullivan put his right hand to his chest and took a deep breath.

“Today was a very good day,” he continued, “and we’re going to build on it, drawing inspiration and continued courage from it for all those held hostage or wrongfully detained around the world. And that includes Mark Fogel.”

Ellen Nakashima, John Hudson and Mary Ilyushina in Berlin, and Catherine Belton in London contributed to this report.