Cassie was a victim of the Columbine High School massacre in Littleton, Colorado in which two gunmen, Eric Harris and Dylan Klebold (who were both students at the school) killed 12 students and one teacher before committing suicide.

Cassie was active in church youth programs and Bible study groups. Her parents called her "Bunny Rabbit" and said she loved to go rock climbing in Breckinridge. She had recently visited Britain and her favorite movie was 'Braveheart'.