I looked up a few of the things luca did. He killed a whore who had his baby. He had a midwife by knife point through his baby from the whore in a furnace I think the baby was a live at the time. He also killed his father, and he deserved killing.

They should have put That stuff in a movie. Then the audience would have a true understand just what Luca was to deal with. He was also totally loyal to the Don.