I'm closest to el Barto on this, but for slightly different reasons. It's partly because I don't feel a human has the capability of determining something as final as purposefully and willfully taking someone else's life. I'm good at rationalizing too, which is where war and things like that come in, but I just feel like it's beyond my ken to know all the facts necessary to end someone's life. I could very easily, though, administer a deep beating if necessary.
Two, I don't want to get caught. I know better than to think that every 14,000 person town has their own Gil Grissom - some STATES don't even have their own Gil Grissom - but luck and circumstance have their power too. I was on a jury about a year or so ago, and did you know that guns only retain a finger print (reliably) about 5% of the time? And yet on TV, guy farts in the crime scene room, and they're able to extract DNA from the gas molecules, run it through the database of the entire U.S. and get a response in 15 minutes. I have no doubt that I can commit a crime and get away with it, but there are always the random variables, and I am not willing to take that chance. Nor is there any person on this planet that I would trust with knowing what I did (not necessarily because I don't trust THEM, though that is 99.9% of the population, but those that I could trust I wouldn't want to burden with that knowledge).