I've found some quotes about the murder of Darrell "Dimebag" Abbott. (Reuters for whatever reason saw fit to include them under the "Oddly Enough" section.)
"Dimebag was a dear friend of mine. I'm absolutely beside myself with grief. I can't for the life of me understand why someone would do this. Pantera toured with me many many times. I'll always remember the signed guitar that he gave me at my 50th birthday party." Ozzy Osbourne.
"It's a sad day when being such a good guitar player can get you killed. Metal will never be the same." Dan Jacobs of Atreyu.
"As a guitar player he was a true innovator. His sound tone and style shaped modern metal and his riffs are constantly referenced by nearly every band in metal including my own. Only recently did I have the pleasure of hanging out with him on a personal level and he was as genuine and down to earth as anyone you would ever meet." Mark Morton of Lamb of God.
Some violent crimes are shocking but you can understand them on some level. When Mark David Chapman shot John Lennon 24 years ago, it was a sick crime but Chapman's twisted worldview at least gave some reason why he did it. Even with other crimes in which the killers died--Columbine, Heaven's Gate, Charles Whitman, even the September 11 terrorists--you got some impression why they did it.
A few years back, in Dan Quayle's hometown, a nut castrated several men and kept their testicles in pickle jars in his apartment. No one's really explained that one either.
I'm not condoning "understandable" violence but on some level it's less disturbing.