Cassie René Bernall (November 6, 1981 – April 20, 1999) was a student killed in the Columbine High School massacre, at age 17.
Initial reports suggested that one of the assailants, either Eric Harris or Dylan Klebold, asked Bernall if she believed in God moments before fatally shooting her. She was reported to have answered "yes". This story led to Bernall being presented as a martyr by some Christians, and served as the inspiration for several songs, including Michael W. Smith's "This Is Your Time" and Flyleaf's "Cassie." 
In the months following Bernall's death, her mother, Misty Bernall, issued the book She Said Yes: The Unlikely Martyrdom of Cassie Bernall. In this book Misty Bernall discusses her daughter's turbulent teenage life, spiritual conversion and martyrdom.
Most examinations of witness testimony state that Cassie was not asked anything before she was shot. According to witness Emily Wyant, who was hiding under a wood table with Cassie, Eric Harris said "peekaboo" before shooting Cassie, while Cassie continued to pray silently. It is believed the famous exchange actually took place between Klebold and Valeen Schnurr, and was mistakenly attributed to Bernall.
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- Cullen, Dave (1999-09-30). "Who said "Yes"?". Salon.com. http://www.salon.com/news/feature/1999/09/30/bernall. Retrieved 2010-10-03.
es:Cassie Bernall eo:Cassie Bernall fa:کیسی برنال fr:Cassie Bernall pt:Cassie Bernall