If they had social media back then and chose to use it, I wonder what Bundy's FB would have looked like, or Dahmer's, etc? Interesting to ponder. I don't necessarily think the killer has to be a genius. It could be as simple as not having that "one clue", possibly a suspect, to compare the evidence to. Also in terms of DNA, LE said it's not the kind we think. So maybe it's not as easy as seeing what felon pops up on the screen. No, JBC hasn't blatantly posted an admission of any kind, but it seems he could have left a lot of clues, like the one he posted 3hrs before his last attack (and his artwork, the stuff he conjured up from his own twisted brain. Could be a lot to read into there). He even posted a screenshot where he said not to make him choke her, in a sexual context. He doesn't seem all that smart, but he sure does seem violent and impulsive enough. JMO
In a way, we know how TB's FB would have looked like. Ann Rule was his FB - if FB is the indicator how the world sees us..
He was able to show empathy, he volunteered at suicide hotline, he was attractive enough. I see some void where male friends should be, and maybe he'd have more female friends on his FB. He'd be professional, in those years he was a Republican (today I think, either libertarian or a centrist-leaning Democrat). He'd post some articles about suicide prevention, new information about Covid, he'd be ironic and glib on his FB. Some photos from hiking and canoe trips (but nothing close to that mountain in Issaquah where he dumped the skulls). Maybe he'd be member of some help groups where women go. And many photos with Liz and her daughter, the family.
You know what I also think? I see some FBs of successful immigrants - all of them try to emulate what, in their minds, average Americans are posting. This is what we would see on Ted's FB - he had no childhood to speak of, he did not quite fit in, so he'd pretend so hard - smiling faces, measured words, thank you, Liz, for being the best... a huge post when he was accepted into law school, with thanks to his wonderful family and friends, and future plans. (Someone would comment, so many years, Ted and Liz, maybe time to tie the knot?) And then the photo of a Beetle VW "farewell, WA, hello, UT".
Dahmer was different. Way more psychotic, so I doubt we'd see a FB, he was a total loner, or his FB would be something not kept consistently. But who knows?