Oh - those 90-s grunge rock bands... it almost always ended tragically:
After a decade battling drug addiction, Layne Staley was found dead in his condominium on April 19, 2002. An autopsy revealed Staley died from a mixture of heroin and cocaine 14 days previously.
I don't think it was any surprise though. Even at "Alice in Chains"'s earliest songs the theme was about drug dealers and addiction.