Dr. Mario Verna's three sons had always heard the stories growing up that their father had a close friendship as a teen with Jorge Bergoglio, better known now as Pope Francis.
They had no idea just how close the bond had been until two days after Verna died from Parkinson's disease on Dec. 3 in New Jersey.
"My dad was a storyteller, but he was also prone to exaggeration, so we never quite knew how much to believe,'' Matias Verna, 49, a child psychiatrist from Scarsdale, New York, told TODAY.
Matias faxed a letter on Dec. 4 in Spanish to the Vatican with his contact information, informing Pope Francis of his father's death and how his father always remembered him fondly. He figured it was worth a shot to try to get a response.
Less than 24 hours later, he was driving alone when, he said, he received a call from an "unknown caller" that turned out to be the holy leader of 1.2 billion Catholics. The two had a one-minute conversation, according to Matias.
"I recognized his voice immediately, and I said, 'Oh, my word,''' Matias said. "While I was talking to him, it was very natural, and he was very human and very calm, and then as soon as I got off the phone with him I felt my legs turn to rubber.
"Then I started crying. It was overwhelming."
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Pope Francis, 81, has become known for his down-to-earth humility, including making personal phone calls to Catholics.
Speaking in Spanish, Matias said, Pope Francis told him he certainly remembered El Flaco (Skinny), which was Verna's nickname in his youth.
"Then he said, 'We are at that age where we're starting to be called back (to God),'" Matias said. "I said, 'I thank you tremendously for these words,' and he said he would pray for my dad at an upcoming Mass."
Matias then called his brothers, Mario, 54, and Paul, 53, as well as his wife and other family members.
"I just couldn't even begin to wrap my mind around it,'' Paul told TODAY. "I knew he had faxed the pope because he had sent me the copy, but I expected that, at most, maybe two months from now we'd get a response from a Vatican spokesperson or a pro forma letter with a stamp signature by the pope."
"Private calls are considered private calls, so we don't comment at all,'' a Vatican spokesperson told TODAY.
Verna and Pope Francis first met when they were in a Catholic Action group as teens in Buenos Aires, Argentina, where Bergoglio became archbishop in 1998 before being named the new pope in 2013.
Verna and his wife, Ana, who died in 1994, had their three boys in New Jersey in the 1960s before returning to live in Argentina.
They came back to New Jersey in 1976 following the political upheaval that led to the country's Dirty War. Verna was a pioneering surgeon at Hackensack University Medical Center, while Bergoglio was rising in the hierarchy of the Catholic Church.
"I thought the pope's words about being called back were very eloquent,'' Paul said. "It was a way for him to relay back to my dad that they're just two guys who happen to be the same age where their time has come or is close at hand, not that one is the pope and one is a doctor from New Jersey."
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Matias got the idea to reach out to Pope Francis and read that the Vatican only answers faxes, so he searched for the fax numbers online. He started the letter by writing "Dear Pope" in Spanish.
"Paul said, 'Are you crazy? You wrote Dear Pope?!''' Matias said. "You're supposed to say 'Most Holy Father!'''
"I jokingly told him he might go to hell for that,'' Paul said. "Otherwise it was a nicely worded note."
Verna was suffering from dementia when Bergoglio became Pope Francis in 2013, but he still remembered his friend.
"My father was known for his hospitality and his ability to engage anyone who walked through his door,'' Matias said. "He also was known for surprises, and for us this tribute was his last little surprise up his sleeve.
"It was the most amazing silver lining I've ever seen in my life."