Havana , Cuba ( CNN ) It might be the most bizarre of the closely guarded secrets from last week 's historic agreement between the United States and Cuba : How did the leader of a Cuban spy ring serving life in a California federal prison manage to impregnate his wife 2,245 miles away in Havana ? As part of the most significant diplomatic breakthrough between the United States and Cuba in more than 50 years , a prisoner swap was made . To uphold its part of the bargain , the U.S. released three Cuban spies , including Gerardo Hernandez , the head of the spy ring known as the Wasp Network . Hernandez had an ear-to-ear smile Wednesday as he arrived at Havana 's Jose Marti International Airport . State TV showed Hernandez as he was greeted by President Raul Castro and then embraced and kissed his wife , Adriana Perez . Cubans watching the nonstop coverage of the prisoner swap were shocked when the cameras zeroed in on Hernandez hugging Perez . She was obviously in the late stages of a pregnancy that had no easy explanation . Not only had Hernandez been serving a double life sentence , but his wife also worked for Cuba 's intelligence services and was banned by U.S. officials from visiting her husband in prison , according to the Cuban government . Rumors swirl in sultry Havana . The subject became the immediate hot topic in Havana where rumors swirled fast about the baby 's paternity and whether the Cuban government could have somehow arranged a clandestine conjugal visit under the nose of U.S. authorities . The couple appeared at another event on Saturday , where together with the other freed spies , Castro and the communist island 's top political and military officials showered them with applause . A beaming Hernandez stood by Perez , whose round stomach was clearly visible for viewers of the live broadcast . As the couple left the celebration , Hernandez hinted at the secret surrounding the pregnancy . `` Everyone 's asking , and we have had a lot of fun with the comments and speculations . The reality is it had to be kept quiet , '' Hernandez told the government-run television channel . `` We ca n't give a lot of details , because we do n't want to hurt people who meant well . '' He said his wife 's pregnancy was a direct result of the high-level talks . `` One of the first things accomplished by this process was this , '' Hernandez said , gesturing to his Perez 's stomach . `` I had to do it by 'remote control , ' but everything turned out well . '' Two sources involved with the diplomatic talks , when questioned by CNN , uncloaked the mystery : During the negotiations , Hernandez 's sperm was collected and sent to Cuba , where Perez was artificially inseminated . The U.S. Justice Department confirmed the story , without going into the details . `` We can confirm the United States facilitated Mrs. Hernandez 's request to have a baby with her husband , '' spokesman Brian Fallon said . What the U.S. would gain . Why would the U.S. government do this ? The artificial insemination was made possible in exchange for better conditions for Alan Gross , a U.S. contractor imprisoned in Cuba . Gross was released last week as part of the prisoner swap . `` In light of Mr. Hernandez 's two life sentences , '' Fallon said , `` the request was passed along by Senator [ Patrick ] Leahy , who was seeking to improve the conditions for Mr . Gross while he was imprisoned in Cuba . '' The discretion on both sides makes sense . For 18 months , officials from both countries refused to admit that they were even holding high-level talks . Officials communicated via back channels , knowing that any leak about the talks could doom the talks . Impregnating Perez involved cutting through bureaucratic red tape at multiple U.S. government agencies . As Perez began to show , officials from both countries fretted over how they would explain her pregnancy and what to do if the baby arrived before the talks succeeded . 2001 conviction . Hernandez was convicted in 2001 of conspiracy to commit murder for his role in the Brothers to the Rescue shoot down that left four Cuban-Americans dead after Cuban Air Force MIGs blew up the two civilian planes as they flew toward Havana to distribute anti-government leaflets . He received two life sentences . Cuban authorities said Hernandez and the other operatives were trying to prevent terrorist attacks from being carried out on their homeland by violent Miami exiles . That the U.S. government helped a man convicted of plotting the murder of four Cuban-Americans and spying on the exile community in Miami will likely further rankle many of the same Cuban-Americans who were already furious that Washington is restoring diplomatic relations with Havana . But Tim Reiser , an aide to Leahy who worked to broker the landmark agreement with Cuba , said helping Hernandez conceive a child led to better treatment for Gross by Cuban authorities and was an important concession to help reach a historic deal . `` The expectation was that this man would die in prison . This was her only chance of having a child , '' Rieser told CNN . Gerardo Hernandez said he and his wife are expecting their baby daughter to arrive in two weeks and they will name her Gema . Patrick Oppman reported and wrote from Havana , Cuba . Evan Perez reported from Washington .
Gerardo Hernandez was the head of the spy ring known as the Wasp Network . The FBI said that it had been investigating Hernandez's activities for more than a year and that he is suspected in at least two other espionage cases. Havana has been abuzz since his wife in Cuba showed up pregnant during news coverage .