Private First Class Gustavo Rios-Ordonez had two young daughters still in diapers when he stepped on an explosive device while serving in Afghanistan. He died when Isabella was 2 and Elizabeth was 7 months old.

Monday marks the five-year anniversary of his death. But this past May 25, like every other year, his girls celebrated his life.

“On his birthday we go up the cemetery and they write on the balloons and just release them so they can send messages to Daddy in heaven,” his widow, Tiffani Rios, told TODAY.

Elizabeth and Isabella Rios at their father's gravesite. Courtesy of Tiffani Rios

“They didn’t really know him, but it’s a good way for them to do something for him. It creates a good little memory.”

Rios never thought anything about the balloons until this year, when one of them found its way back to her in Eaton, Ohio.

Private First Class Gustavo Rios-Ordonez, five years ago with his two daughters, Courtesy of Tiffani Rios

When her daughters last visited their father’s grave, they brought balloons with them as usual. Isabella, now 7, wrote her own messages but Elizabeth, 5, relayed what she wanted to say to her mom. On one of her three balloons, she wrote: “I love and miss you daddy,” along with her name, hometown, and the date, "5-25-16."

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Nearly two weeks later, Heidi Kern Schwartz found the balloon as as she was walking to pick up her son from his school — more than 800 miles away in Newton, Massachusetts.

She saw the deflated balloon in the grass next to the sidewalk she was on and noticed the writing on it. She initially thought the balloon was a memento from Memorial Day but she soon realized the date written on it didn't match with the holiday.

"But I was pretty sure it was from a kid because it said, 'daddy,'" Schwartz said.

After looking up information about Eaton on the internet, she posted a photo of her discovery to the Facebook page of the town's Veterans of Foreign Wars.

“Does anyone know who Elizabeth is? I'd love for her to find out how far her balloon went!” she wrote in the post.

The picture quickly circulated among Rios's Facebook friends.

Courtesy of Tiffani Rios

“Since everyone here in this little tiny town knows who my kids are, they all started tagging me in it and asking if it was Elizabeth’s balloon," Rios was. "When I saw it, I said, 'Yup, that’s hers.'”

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While the girls didn’t have much of a reaction to the finding — “they’re too young to understand” — Rios was thrilled.

“At first I was shocked, but then I got excited. I thought it was really cool,” she said.

"It’s the first time one’s ever been found. I figured it would land on some field somewhere, or in the garbage or something. I didn’t think someone would actually find it and try to find the owner or the person who released it."

Gustavo Rios-Ordonez and Tiffani Rios Courtesy of Tiffani Rios

Rios exchanged messages over Facebook with Schwartz, who has since mailed the balloon back to her.

"I had a feeling (Elizabeth's) dad was a soldier, who had passed away," Schwartz said. "I thought this was sweet. She was trying to remember and connect with him in a way that only a little girl can."

Rios, 27, now has two young boys in her family and plans to remarry in the fall of 2017. But she said her daughters will always continue their tradition of honoring their father. And she's happy more people have since learned about her late husband.

“This is all pretty exciting. He lives on this way,” she said.

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