. >> hello, and welcome to "dateline," college student reagan tokes was smart, beautiful, and as graduation approached her life was brimming with possibility. the bright future ended before it began when reagan was found shot to death. investigators quickly closed in on a suspect, but a stunning discovery would reveal an unbelievable blind spot in law enforcement and color her family's grief with rage. here's andrea canning with unchecked evil. >> look at the pictures, and you can see, reagan tokes was a ray of light. >> she was a vivacious ball of energy. >> she was always just so fun to be around. she felt like part of my family. >> i still don't think i've ever met anyone that could make me laugh like she did. >> a caring friend, a devoted daughter. she radiated life from her very first breath. >> she came out eyes wide open, just ready to take on the world. >> which made her final moments all the more incomprehensible, terrified and alone in that darkened field. >> you just think about what she had to endure, and what she was ultimately clinging on to at the end was just to live. and be