Now, this is just speculation. There's absolutely no basis for it! I don't believe it... (s)[/COLOR]
:D I'll have to justify my thoughts:
Alcohol has a blocking effect, which is strange if the Mafia didn't take advantage of it.
Heroin has good pathogenicity, so there's no need for it to be conspicuous during killings.
Opium doesn't have any such properties + it appears after cholera - clearly killer #1)))
