Paul Whelan's brother expresses gratitude over Russian prisoner exchange, eagerly awaits reunion

Paul Whelan's family said they were doubtful that they'd ever see him again after he was held nearly six years in captivity in a Russian prison, according to David Whelan, Paul's twin brother, who has pushed for his freedom.

But after Paul Whelan was released Thursday after 2,043 days in captivity as part of a historic prisoner exchange between the U.S., Russia, and other nations, David Whelan told ABC News' Whit Johnson in an exclusive interview that his family was overjoyed.

"I didn't really allow myself to believe it was going to happen until I saw that announcement by the White House," Whelan said.

David Whelan said his family had received some initial guidance from the State Department that there might be some news involving his brother's status. The family, which he said had become "detailed Russia watchers," saw "pieces move around" but remained cautious until there was official word from the White House about Paul Whelan's imminent release.

"We had been through two prisoner releases before where he did not come home," David Whelan said.

Whelan further said that he didn't have 50-50 confidence that his brother, who was jailed in Russia in December 2018 on charges of charges, would ever be freed, given other cases around the world of Americans being jailed. These include Mark Swidan, who has been imprisoned in China on drug trafficking charges since 2012, and Kai Li, who has been held in China since 2016 on espionage charges.

"We didn't have high hopes that this was ever going to happen," David Whelan said. "The difficulty in these situations is that the family has so little control. Paul was a pawn of the Russian government and became part of a geopolitical fight that really has nothing to do with Paul or our family or anything he did."

As part of the multi-nation deal with Russia, Paul Whelan, Wall Street Journal reporter Evan Gershkovich, Alsu Kurmasheva, a Russian-American journalist, and Vladimir Kara-Muza, a legal permanent resident of the U.S., were released from custody Thursday. In exchange, the U.S. released Roman Seleznev, Vladislav Klyushin and Vadim Konoshchenock from prison and sent them back to Russia.

David Whelan said he had no comment on the machinations that went into his brother's release.

"Once Paul was free, it was almost like … closing a chapter in a book, and I'm ready to move on," he said.

Whelan noted, however, that the release may pose more difficulty for "the next family [and] the next American that is held by Russia."

"I'm not sure what concessions the U.S. government can make," he said.

As for what's next for Paul Whelan, David said they are going to give him the time to become reacclimated and resettled after he is finished with his government debriefing and health checks once he lands in the U.S.

"We're hoping he will take that time and have a chance to meet our parents," he said.

David Whelan noted that his brother does have a long road ahead, since Paul Whelan lost his house and job while in custody. However, another sibling was able to take care of his finances over the last few years.

"Having that financial starting point is going to be a help for him," David Whelan said.