The big angle on Showalter right now is that his parents are both doctors and the three of them appear to be in Africa at present; there’s a screenshot from Facebook posted by his mom in the video above.
The case gets confusing with multiple people named “Jack,” but this Jack is a guy who appeared in one Xana TikTok, is apparently a weird drunk, followed Maddie on Instagram (maybe they followed each other), and lived a 30-second walk up the hill from the house. If Kaylee was indeed the target, especially considering he has the same first name as her on/off boyfriend of six years, it’s completely reasonable to think that maybe he was really into Kaylee, maybe they even hooked up on her break with the other Jack, and then she told him she wasn’t interested or told him she was reconciling with the other Jack, or laughed at him that night … and that set him off.
All theories right now, and we don’t know. But it’s definitely plausible.