I would consider someone that shows no remorse for trying to murder others, that fantasizes about murdering others, evil. Sometimes psychopaths are born that way, they have what's termed termed callous and unemotional traits. The vast majority of them end up harming others so yes I would consider them evil.And you called them evil for that in a context where inherent evil is being used as an excuse for extermination. Please recognize this.
Humans of course can change, but most treatment of psycopaths fail or at best have limited success. Obviously good and evil are just labels we use, but what else do you call someone who's murdered multiple people "just because" who doesn't value the lives of others at all? That doesn't even recognize what a look of fear is?
In any case, this has gotten off track. I just disagree with the idea that we can positively know with any certainty that all intelligent species will share the same concept of good and evil as we do.