David Gimelfarb was last seen at a national park in that country, preparing to take a short hike. For the past year, his parents have been consumed with trying to find out what happened to him.
When Gimelfarb vanished, police found his car, his belongings and his passport, but not a clue of what happened to him.
"This year was worst year of my entire life. This year is unbearable year. This is the year which I don't want to wake up in the morning; I wake up only because I believe my son is alive and that we will find him," said Luda Gimelfarb, David's mother.
Luda and Roma Gimelfarb do believe their son is still alive. There have been a number of sightings in Costa Rica of a man who resembles David Gimelfarb.
"When people describe him, they describe somebody who looks exactly like David. In the way how he behaves, it's sort of like David, even though he doesn't behave right he's still a very nice guy. David's a very nice guy," said Roma Gimelfarb, David's father.
They wonder if it is possible their only son was attacked or fell. Does he have amnesia?
"The way they describe this person... he doesn't know who he is. He basically roams the country," Roma Gimelfarb said.
And by the time a sighting is reported, the man is gone.
The Gimelfarbs have poured their time and resources into trying to find their son, traveling to Costa Rica, hiring a private investigator, handing out thousands of flyers.
Their supporters have held rallies in Chicago. David Gimelfarb would be 29 now.
"He's our only child, and we were very close," said Roma Gimelfarb.
"Not hearing his voice and not seeing him, it's just very hard," said Luda Gimelfarb.
The Gimelfarbs are organizing a rally for Wednesday afternoon at the Daley Plaza in the Loop. They want to keep their son's case public. They're hoping for help from the U.S. State Department and the government of Costa Rica.