I remember the first time I ever felt deep guilt and shame for doing something morally wrong. I don't mean like lying--I'd done plenty of that--but I only ever felt bad about it because I knew I wasn't supposed to do it. Oh, yeah, and there was one other condition to be met: I had to get caught.
When I was maybe 5, my parents built a cross fence in our front yard. When they dug up the earth, there were so many Earth worms! I adored the Earth worms, separate and severally. I collected them. I caressed them but I was very careful with their squishy little bodies. I didn't want to harm them.
Come lunchtime, my parents encouraged me to leave my beautiful little worm babies outside. The new fence had these nifty V shapes in it so I gathered my worm-pups up and nestled them together in the crook of a V. Then I went and had lunch.
I wandered out into the front yard maybe an hour or two later. As I came up to the fence, I saw that my wormies were standing tall. Could they be looking for me?
OH GOD THE HORROR
They weren't looking for me, they were looking for... anything. Water, dirt, rescue, water.... Did I already mention water? They had strained to get anywhere they could, other than where they were. And they had dried up in that position.
Okay, so maybe that's more your manslaughter-level moral culpability than it is your murder-level. Still, decades later and I flash on those worms and feel the guilt and shame wash over me every time I exceed a clear moral boundary. That's generally how I know when I am just wrong. Those moments have nothing to do with getting caught.