[RogerBW]

Ah, I didn't pick up that the cups had been put away. OK, that's not going to be regarded as evidence. So I don't see this causing investigative problems for the cultists. A car rental lot presumably has external surveillance which would have caught them going in, but that's been compromised when the internal recordings were wiped, and as you say nobody's going to be surprised by it not working.

I don't have a feel for the Houston police. If someone takes a serious interest, they could notice and put together the blood chemistry, lack of stressors in the victim's life (and e.g. email/IM records that say he was planning to do something that evening), lack of a suicide note and hesitation marks (not probative but suggestive), lack of any history of mental illness, and think "hmm, maybe there is something weird going on here" – but they have nothing to point them at the perpetrator, not even enough to say definitely that this was a murder. And if they're in a hurry they might just say "eh, looks enough like a suicide" and close the case.

In a few days' time when the car is found to be missing (I assume they won't return it) and someone's complaining about his booking being changed, that starts to align things in the same direction. But as you say that's outside chummy's planning horizon.