Last report on this I saw last week said the toxicology reports found only marijuana (presumably THC metabolites) in the "zombie's" system. No bath salts, no LSD, no coke, just THC.
Here's the thing. The original autopsy report claimed that NO FLESH was found in his stomach (where did the eyeball eating come from?) and that "undigested" pills were found in his stomach. Any pill in your stomach is at least partially digested but I digress. There hasn't been a peep about those pills and what they were since that initial coroner's report.
Looks like this story has turned into a future urban legend based little in fact and lots on media hype and lies.