A Question of Writers' Quotes: Post Osama

The following quote attributed to Martin Luther King Jr. has been appearing all over the net and in social media apropros of the death of Bin Laden.

"I mourn the loss of thousands of precious lives, but I will not rejoice in the death of one, not even an enemy. Returning hate for hate multiplies hate, adding deeper darkness to a night already devoid of stars. Darkness cannot drive out darkness: only light can do that. Hate cannot drive out hate: only love can do that." - Martin Luther King, Jr.

However, Seth Abramovitch, writing in gawker.com has his doubts, which seem valid enough. He feels that the first sentence is completely fabricated, because King Jr. hasn't seen or experienced any deaths totalling the loss of thousands of lives.

The opponents of the above quote have their own quote of dubious origin attributed to Mark Twain (trust the social media to be schizophrenic):

"I have never killed a man, but I have read many obituaries with great pleasure."

Turns out it was actually said by Clarence Darrow, not Mark Twain.