After the war, Katz said her grandfather spent the rest of his life trying to find his brother, writing countless letters to no avail.
"I don't even know if there are words to describe it, this was all he wanted, he just wanted to know that his brother survived," Katz told ABC News.
This year, Katz did some digging online using social media and a genealogy site to try to find her relatives. "In a few hours we found more than we ever knew in 70 years of searching," Katz told ABC News.
Unfortunately, neither brother would ever know what happened to the other one. Katz's grandfather did not live to find out that his beloved brother had not only survived the war, but had built a family in Sakhalin Island, Russia. Nor did his younger brother find out that Abram had built a family of his own in New Jersey.
On April 20, 2016 the two families of the brothers Skyped for the first time. Katz said everybody was in tears.
"He was my hero," Katz said of her grandfather, who passed away in 2011 at the age of 95. "He was very kind, very warm. He was full of love."
"He had nightmares every night about the Holocaust, even when he was in his nineties he would have them," she continued. "But he would still wake up and find a way to be the best Grandfather and the best Father. He had a lot of struggles and a lot of pain, but he still found some kind of way to live a life full of love and kindness."
Katz initially tracked her grandfather's brother using JewishGen.org a free, online, non-profit resource affiliated with the Jewish Heritage Museum in New York City. Chaim died in 1970, but Katz was able to find his son, Evgeny Belzhitsky.
Avraham Groll, the Senior Director of Business Operations for JewishGen.org told ABC News that the website has more than 700,000 registered users throughout the world and more than 22 million Jewish records archived to help reunite Jewish families who were separated during the Holocaust.
"We have something called the family finder, a resource that allows someone to say that they are looking for a particular name and then find someone who can connect with that," he said.
The site also has a myriad of other resources to help people reconnect with their family, Groll said, including information on how to read a Hebrew tombstone or how to interpret passenger list annotations
Katz says her family talks to their new found Russian relatives everyday.
"It's happy, but it is also mixed with sadness," Katz said, citing how much her grandfather searched for his brother and how much he wanted to see him. "I think he is still kind of around, I think he and Chaim kind of orchestrated this."