ETA: I asked myself a few questions. One, everyone says he is from Delphi because he knows the area so well. In what scenario would he be not from Delphi and yet know it so well? (There are two, he grew up here, or he has the reason to come in here, occasionally). Two, he is well-trained in two things, killing, and not leaving traces. Luck of a hunter? Or something very different? (And did he plant the DNA, too?) Three, someone mentioned that he was not seen on any camera. Who can know how to avoid them? Four, the theme of “revenge” periodically pops up here. Either it is a psychotic local cat-fisher, but a person so angry would be leaving other traces. Dead, tortured, animals, for example. Yet this crime came out as a complete surprise. Is he non-local? Or he simply needed to eliminate the girls for a reason that had nothing to do with his feelings? Then what was the motive? And then, I can imagine Libby, technology-savvy, with her wide interests and hobbies, she could have run into something near the bridge and did not understand what it was. Or took it for something from their usual game. And she could be persuaded to return it back, still not understanding what it was. And now that DNA does not match anyone, I guess.