There may be a scientific reason for why psychopaths are so cold blooded.
Harvard University scanned the brains of 49 medium security inmates…not the coldest of the cold….and found their brains may indeed be wired differently that they typical one. It seems they’re hard wired for short term rewards.
The defect may stop them from thinking about the consequences. Lead researcher Dr. Josh Buckholtz aims to change thinking about these people from evil to bad decision makers, despite what he calls their “emotional deficits.”Source: New York Post
10 psychopaths you didn't know existed: https://listverse.com/2011/02/09/10-evil-psychopaths-you-probably-dont-know/