WASHINGTON — Christopher Astle and Emily Yanich were teenage pals strolling back from a 7-Eleven that summer afternoon — two ordinary kids on an ordinary Wednesday after school — when they found the abandoned baby.

It was Sept. 6, 1989. They discovered the newborn wrapped in towels at the front door of a townhouse in their suburban Fairfax County, Va., complex and took the infant to Emily’s, where her stepfather called police.

Authorities took the baby girl, who was later adopted. Chris and Emily, both 15, went on with their lives, although Emily often cried when she told people the story, and the two called each other every Sept. 6.

Twenty years passed.

Then, on Dec. 2, a college student named Mia Fleming sent them both a message via Facebook: Might they be the same Chris and Emily who had once found a baby left at a stranger’s door? If so, she just wanted to say thanks.

After all these years, the little girl they had found had found them.

Chris and Emily, both 35, remained close as they grew up, moved and married, bound by their rescue of the baby.

Mia, once she learned her story, never forgot them, and after numerous tries over several years managed at last, through the power of the Internet, to track them down.

“I didn’t know how they would feel,” she said.

Emily said: “It’s like a miracle. . . . My heart is filled now. There was always a little spot missing.”

Chris said, “It’s the best Christmas present I have ever gotten.”

A reunion is being planned so the three can see one another again.

Two typical teens

The saga began that day in September about 4 in the afternoon. Chris, of South Riding, Va., was a C student and heavy-metal music fan who wore Metallica T-shirts — “an average, ordinary high school kid trying to find his way through life,” he said.

Emily, now Yanich-Fithian of Lewisberry, Pa., sang in the school chorus and had a job at the mall. She recalled that they had probably gone to the 7-Eleven to buy cigarettes.

Chris and Emily had just returned to their complex when they heard the baby crying.

The cries were coming from the front landing of a townhouse, where it looked like no one was home. Chris started up the steps and spotted a bundle of orange towels.

“I walked over and carefully unfolded the towels, and here’s a naked newborn baby girl, just crying,” he said. “She still had part of her umbilical cord attached. . . . She had a full head of hair. I picked her up and held her. She kept on crying. . . . I was completely freaked out.”

He and Emily banged and kicked on the door and rang the bell. No one answered.

Had someone forgotten the baby? Was she hungry? Should they go back to the 7-Eleven and get some food? Should they leave the baby? Should they take her? Would they get in trouble? They decided to take her home.

As they walked up the driveway to Emily’s house, her stepfather, Bill DeLancey, joked, “What did you guys bring home this time?”

“Bill,” Emily said, “we found a baby.”

“He about fell out of his chair,” Chris recalled.

The teens explained, and Bill called 911. Police, medics and firefighters came quickly.

“The next thing we know, the paramedics took the baby, and she was gone,” Chris said.

It turned out that the baby was less than 12 hours old, officials said later. She weighed 6 pounds, 10 1/2 ounces and was 19 inches long. She had dark eyes and dark hair, and was in excellent health. There was no trace of her mother.

The teens later bought the baby a teddy bear — possibly at the 7-Eleven, Chris said — visited her in the hospital and went back to high school.

Emily’s family moved to Pennsylvania about a year later. She married, had two kids and got a job driving a school bus. Chris became a computer engineer and also married. But they always wondered who had left the infant, and why.

A child’s discovery

Mia had been adopted by a British couple living in suburban Washington. At about 9, she was going through the scrapbook her mother kept about her childhood and found an envelope. Inside was a newspaper story.

At first, Mia said, it bothered her that she had been abandoned, but then she became curious about the two teenagers who had saved her and whose teddy bear she still had.

She knew their names from the newspaper and said she began trying to find them on Facebook when she was in high school. But there were many Chris Astles on Facebook, and she was leery of trying them at random.

On Dec. 1, Mia, a reserved and soft-spoken junior with dark hair and a tattoo of a bull on her left shoulder, discovered on Facebook a person who looked as though she might be Emily. She spotted Chris’ name on Emily’s list of friends. This had to be them.

That night, she “friended” them on Facebook. Neither recognized her name. The next day, both messaged back saying, essentially, “Who are you?” Mia agonized about her response.

“I was so nervous thinking about what I would say to them and how they would react,” she said in an e-mail. “I was . . . afraid that they wouldn’t want to hear from me, or would think I was some sort of crazy person.”

That evening she wrote back to Chris and Emily, then ran off to class, worrying what they might think.

“Hi, I’m sorry to bother you,” she wrote to Chris, “but if you are the Chris Astle I was looking for then I just want to thank you. You and Ms. Yanich found me on someone’s doorstep when I was an infant. I don’t really know what else to say, but thank you. If I’ve gotten the wrong person then I apologize! — Mia”

In his office, Chris read the message and exclaimed out loud. A buddy down the hall heard him and called, “Are you all right?”

Chris said he was fine.