For what it's worth . . . I spoke to someone, who happens to be Mexican, and he told me that it's generally known and reported in Spanish-language media that the unfortunate musicians are involved in gangs, drug activity, etc. "Like gangta-rap," he explained. I don't know if this is true or not, and nothing justifies cold-blooded murder, but if true this perhaps shines some light on the mystery of why this is happening.