Perhaps HYDROGEN cyanide (deathcamp Zyklon B) would arouse suspicion when purchased, whereas the common industrial chemical SODIUM cyanide would have more plausible reasons for being in someone's possession.
You need very pure hydochloric acid, a fully contained atmosphere. An industrial labratory..... Self-contained breathing apparatus, chem suits, gloves, TRAINING, lol.
Yeah, a hotel room bathroom sink ain't gonna make ya Mr. Wizard. It's gonna make ya Mr. Dead Jihadist.
AFTER the body was discovered and autopsied the police were sent back to look for cyanide. Likely, the coroner opened up the body and smelled almonds, a telltale sign of cyanide poisoning they are trained to smell.
In any case, there are a host of pathogens at every hardware store that nut-cases can attempt to use to obtain "martyrdom".