"None of the above constitutes a snuff movie as the term is usually understood. It's not out of the realm of possibility that one will yet turn up. But the notion that there is some sort of snuff movie industry out there, complete with film crews, lab technicians, and, God help us, sacrificial actors; that these people film themselves committing capital crimes and sell the result to strangers; and that for nearly 30 years they've succeeded in concealing all traces of their handiwork, strikes me as absurd."
Put that way, it really doesn't pass the smell test.
When hardcore films were illegal there were still labs that would process and print such illegal works.
Wear a mask and the murderer is an unknown. Even todays Islamofascists making snuff recruting videos mask their identities.