Does Evil Exist?

Writing murder mysteries, I find myself awash in the cliches of the genre, specifically regarding evil.  In a murder there must certainly be evil as at least one of the parties has committed the most egregious crime we can imagine.  It goes without saying!  Certain scientists have spent the last several years lauding themselves for ridding us of the concept of evil though, saying if you believe (believe being the operative word) in evil, you must believe in good (read god) and no one has been able to prove that.  These scientists say that what we think of as evil is a malfunction of the brain in conjunction with the result of bad upbringing.  They explain Hitler by saying his "evilness" was a result of a mosquito bite in the trenches of WWI and the probable encephalitis that mosquito was carrying.  I can think of at least 6 million people who could give a damn about the reason for his evil, his madness.  So maybe the question is wrong.  Bad behavior most certainly does exist but when you call it bad behavior instead of evil you realize you have complete control over it.  It's not a devil that got inside you and is running the show, it's your own bad behavior which you can change any time you want.  It might not be easy--what with nasty chemicals and bad learned behavior--but the choice is still yours.  And that makes for a much more satisfying murder mystery, don't you think?