Psychopaths are surprisingly common; however, very few of them are deadly predators. They all share the inability to take responsibility and therefore, blame others. Empathy is generally unavailable to psychopaths but they often try to mimic empathy to play up to an audience as in game playing. That kind of manipulation is obvious to most people. People who ignore empathy in favor of a desired goal, like money, can turn psychopathy on and off as they need. That group is not composed of hard-core psychopaths, but is a subcategory like narcissists.
It would not be surprising if Trump had a murder buried in his past, but not necessarily by his own hand. He has bragged about getting away with murder on 5th Avenue.