This is where things always get extra confusing when discussing crime. A killing is never really "rational" from an ethical or moral standpoint, except for ext

This is where things always get extra confusing when discussing crime. A killing is never really "rational" from an ethical or moral standpoint, except for extraordinary situations like self-defense. But premeditated murders are rational in another, more purely functional sense of the word: the killer was not untethered from reality, they understood the consequences of their actions, and took a series of concrete steps toward achieving the murder.