So I've been thinking about how he got ML to meet him in the park. Understanding a lot more about his conman, pathologically lying, charming at first or on the surface narcopath personality, and following other cases where you want to say to the woman involved, "no! don't trust him" but it's too late, here are a couple theories:
1. The No Sex/Friends Meeting Card - So I can imagine a scenario in which they've been talking and flirting for awhile, and he has become increasingly persistent or aggressive about meeting, and because he's up late, she's bored on the flight, they are texting or messaging and he proposes a meeting, she declines, says she's not up for sex, circumstances, etc. He suggests, "hey no, I don't want sex, I just want to meet you. We'll just talk, hang out, in fact, we won't even go to my house - we'll just meet at a park, maybe smoke some pot and hang out and talk in my car." She falls for it, and it kind of explains her comfy attire. Sending the "friend zone" signals. (I've had guys try this line many times, but I'm a lot older and more cynical than I was at Kenzie's age.) Maybe Mr. "Cost is No Object" promised her other things. I don't know. No victim blaming, the guy is a psychopath con man. The second she gets in the car, he incapacitates her and takes and turns off her phone and it's game over. He was vastly bigger and stronger than her.
2. The "I'm Having a Crisis" Card. Kind of the same as above, only this time he plays the sympathy card. Oh, I recently lost someone too - my grandmother/mother (narcissists do this a lot to get you to get your guard down) died, etc., whatever, I really could just use a friend to talk to. Really, no sex, we'll just talk in the car and I'll drive you home after.
Also I don't really understand how anyone can think this was accidental, when his sex and violence obsession is obvious, many people got a creepy vibe from him, etc, not too mention that he clearly planned this to a degree to not link back to him. If she was a willing participant in sex, for example, why the subterfuge? He clearly (IMO) has been having sex, torture, and grisly death fantasies for awhile. ML was just his unlucky victim.