"I just wanted what was fair," Hummel said. "She couldn't deal with that."
In the summer of 2012, Maria Pfeifer planned a vacation to her native Slovakia with both Jerry and Sasha, a place she had gone to and returned from often. But not this time.
“That day came and went,” Hummel recalled. “She was not on the plane she said she was going to be on.”
Authorities said what happened to Hummel and Bob Pfeifer is growing increasingly common. The State Department told “20/20” they now see up to 800 cases of international parental child abduction a year.
But the Pfeifer/Hummel case was unique, not only because the alleged abductor had two boys from two different fathers, but because she didn't simply return to her homeland. She disappeared, and authorities were convinced she was a mother on the run.
“It’s tragic enough to take a child away from one of the parents,” Bob Pfeifer said. “It’s another thing to live a fugitive life with a child.”
With Maria Pfeifer failing to return from her vacation with Jerry and Sasha, the Los Angeles courts awarded full custody of the boys to their fathers. Both men got to work searching for their sons, but the weeks soon turned into months.
“The world is too small a place. Everyone leaves a footprint. Also, it’s a mother and two children, how long can they possibly hide for?” Hummel said.
While Hummel hired an international child recovery specialist, Bob Pfeifer spent months meeting with the Los Angeles police and district attorney pressing for criminal charges. On the anniversary of the last time he saw Jerry, Bob Pfeifer was at a turning point.
“We had no money left, had no leads, had nothing to lose, so the idea came up to go public and use social media…to tell the world, to share the message across the Atlantic,” Bob Pfeifer said.
“I helped him build the Facebook page and build “Little Jerry’s Army”…which became huge,” Bob Pfeifer’s friend Stacey Dutton told “20/20.”
In time, the Los Angeles district attorney finally pressed charges against Maria Pfeifer: two felony counts of Child Detention with Right to Custody. If he ever got a solid tip from supporters, Bob Pfeifer knew he had the charges to go after her.
Following a lead from one of Maria’s own friends that she may have been in Paris, France, Bob Pfeifer headed there and, without an appointment, walked straight into the U.S. Embassy asking for a meeting with special agent Eugene Casey with the FBI.
Agent Casey immediately began working on Bob Pfeifer’s leads from his social media campaign. While the Paris lead turned out to be a bust, Bob Pfeifer returned to California and focused his efforts on Slovakia.
“We would take a photo and the message in the native language and literally post it on every Facebook page in the target area, whether it was a bar, a hair dresser, an entertainer,” Bob Pfeifer said. “Thousands of hours went into this.”
Shortly after, reporters in Slovakia learned of the story and helped to further spread the word throughout the country. Through his efforts, Bob Pfeifer then received crucial clues about where Jerry and Sasha were and how his ex-wife might have been disguising her sons that he turned over to agent Casey.
More than a year after Maria Pfeifer went missing with her two sons, agent Casey called Bob Pfeifer and Hummel to tell them their ex-wife was finally about to be arrested by police in Divonne, France, just over the border from Geneva, Switzerland.
Watch the full story HERE to find out if Bob Pfeifer and Larry Hummel were ever reunited with their sons.