i think there is a body out here. they have a body of a young woman that matches the description of reagan. i just kept saying, it has to be wrong. reporter: who would want to hurt reagan? investigators would start with those closest to her. we figured it was probably somebody she knew. and ex-boyfriend, current boyfriend. reporter: but miles away, a string of alarming encounters. he had a knife and put it to my neck. i heard a voice say, don t turn around or i will shoot. reporter: could there be a connection to reagan s murder? the answer would leave an entire city and rage. how does this happen? they could ve connected the dots sooner. the system failed reagan. reporter: hello and welcome to dateline. college student reagan tokes was smart. beautiful. determined. as graduation approach, her life was rooming with possibilities. but that bright future ended before it began when reagan was found shot to death. investigators quickly closed in on itsel