Munzer didn't die of steroid abuse.
Take Arnold, for example, but there are thousands of bodybuilders with visible pectoral/deltoid muscle fibers/striations. Munzer is the most extreme, but yeah, his death clouds the issue. 
Sure dehydration was the culprit

The authopsy revealed that he had several tumors in his liver, organ that melted during the procedure.
I don't believe that diuretics and to much chicken breasts was the cause.