BEFORE I tell you about a one-armed teenager who is a star athlete at her high school in Washington, D.C., let me take you back a dozen years to Sierra Leone, in West Africa.

A little girl there became an unlikely global symbol of human depravity. Sometimes dubbed “peace girl,” she had the sweetest smile and an amputated arm — making her the much-photographed poster child of atrocities committed by a militia that chopped off the arms and feet of civilians. Madeleine Albright, who was then the secretary of state, was photographed cradling the girl, and Sierra Leone’s president took her to peace talks.

Those wrenching images of this girl, whose arm was amputated after she was shot, and other children whose limbs were hacked off by the militia built the global political will to intervene and end Sierra Leone’s civil war (Britain did the heavy lifting). I had been fascinated by the girl as an example of the power of individual stories to help end mass atrocities — and then I heard, from Albright, that she is now an American.

I dropped by her home in Washington and found 15-year-old Memuna Mansaray McShane, a wonderfully adjusted high school freshman who plays on her school’s varsity soccer and basketball teams.

“In basketball, you only use one arm,” she explained. She paused for a moment, and then acknowledged: “Except to shoot or catch the ball.” Another pause and a sheepish smile: “I guess that’s a lot.”

She added defiantly: “I can do anything people with two arms can do. Except monkey bars.”

Memuna has no clear memory of her early childhood in Sierra Leone, but she has a photo of her family on the eve of war. She is with her parents and three brothers, all beaming contentedly in what seems a well-off house in the capital.

Then the militia attacked. Her father fled to a different part of Sierra Leone and later died in unclear circumstances. After he left, Memuna’s mother and grandmother apparently took the 2-year-old girl and hid in a mosque. By some accounts, it was Memuna’s crying that caused the fighters to look for people hiding there.

When the fighters entered, the grandmother picked up Memuna and ran. The gunmen shot the grandmother dead, and some of the bullets shattered Memuna’s arm and grazed her side.

Memuna’s mother apparently ran toward her injured daughter. That’s when the gunmen shot her; she died of her wounds about a month later.

Memuna’s older brother, Alhaji Mansaray, then just 11 years old, scooped up Memuna and carried her to a hospital across town, saving her life. But the hospital was in chaos, and it took three days for a doctor to see her. By then it was necessary to amputate her arm just below the shoulder.

At age 4, Memuna was brought to the United States by the Rotary Foundation for medical treatment. Two years later, she was adopted by Kelly and Kevin McShane; Kelly had worked in Sierra Leone in the Peace Corps.

Memuna was spoiled at first: she had figured out that adults cave at demands from an adorable one-armed girl who cries. But the McShanes would have none of that. They have a son, Michael, the same age as Memuna and a daughter, Molly, two years older, and Memuna ended up having to wash the dishes along with the other kids.

“We just wanted her to be a normal little girl,” Kelly explained.

Indeed, Memuna seems to have had a fairly typical life. “We had trouble teaching her to ride a bike,” Kelly said. “But we went rock climbing, swimming, pretty much everything.”

Memuna was impressed the first time she searched the Web for her own name and saw the photos. “I thought it was pretty cool that I got to meet all these famous people, like Bill Clinton and Hillary Clinton,” she said.

The McShanes have made two family trips to Sierra Leone, and Memuna was taken aback at her fame there. “A lot of people were crying and saying, ‘You’re alive!’ ” she remembered. The McShanes hope to bring her three brothers, including the one who saved her life, to Washington for a visit this year if they can get American visas.

Charles Taylor, the former Liberian president who helped engineer the Sierra Leone savagery, recently became the first former head of state to be convicted of war crimes by an international court since the Nuremberg trials. Justice triumphed, and Sierra Leone has moved on. So has Memuna.

Once a symbol of suffering caused by the human capacity for evil, she’s now just a teenage girl with dazzling moves on the basketball court. She’s a poster child of nothing at all — just a happy kid who is a powerful emblem of the human capacity for resilience.

I invite you to comment on this column on my blog, On the Ground. Please also join me on Facebook and Google+, watch my YouTube videos and follow me on Twitter.