Grinning from ear to ear on the pages of her high school yearbook Kayla Mueller looks every bit the all-American teenager. The lively girl from the small town of Prescott, Arizona is smart, gregarious and enjoys a wide circle of friends. But on viewing these photos from her school years - obtained exclusively by Daily Mail Online - few would have guessed that years later this young woman would wind up in the hands of terror group ISIS. Aid worker Mueller was taken captive by the Islamic State in Allepo, Syria, on August 4, 2013, when she was leaving a hospital.
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Kayla Mueller was an award-winning volunteer at school in Prescott, AZ
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She was voted Best Personality, Best Dressed, Best Smile in year book
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Friends and teachers said she 'wanted to change the world'
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She traveled abroad - living and volunteering with aid groups in northern India, Israel and the Palestinian territories, then treated AIDS in Arizona
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The 26-year-old was snatched by ISIS as she left hospital in 2013
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Fears she has been killed by Jordanian airstrikes targeting the group
She returned to @placeholder in 2011, where she worked at an HIV/AIDS clinic and volunteered at a women's shelter.