Some background about me and my political leanings...I chose "no party affiliation" when I registered to vote at 18 years, but I sometimes vote Libertarian, Green, Democrat, and sometimes Rublican. Republican usually when the candidate is Moderate. It's a complicated decision involving which problems need fixing and which solution I feel is the most efficient one per the situation. I'm an agnostic/atheist. I care very much about the environment, and my house is off the grid. I'm generally lefty when it comes to everything, but I can't stand most democrats. BUT the religious right scares the shit out of me. I do, however, own guns. I have killed varmints on my property while protecting livestock, and I enjoy target practice. I like that when my husband is out of town I have a means to protect myself and my son. That being said, I hate the NRA. And I support some gun control laws. Once upon a time when I was Catholic, I was very pro-life and pro-death penalty. I am the opposite now, but I understand the viewpoint to a certain extent so will engage a bit in this discussion.

As I said to Aemon above, a very short answer is this: in one scenario the innocent life has done nothing to "deserve" being killed. In the other, they have screwed up their chances royally, and therefore deserve to die a death.

That is only part of it, but it's a start. I didn't answer your question specifically, but I think the above is a greater example anyway.

*edited to change "you" to "liberals" because I have no idea what the OP actually believes.