nobody knows where she is. >> something's wroong. something's bad wrong. >> where was skylar. someone was hiding something. >> it was the fbi. they were serious. >> twitter, instagram, facebook. you just see things. ridiculously out of control. >> she was like, well, she'll blackmail me. >> it was such a shocking and scandalous kind of case. >> this was diabolical. >> evil comes in all shapes and sizes. >> this is "dateline."