People are inherently both good and evil. I do not believe people are born evil. They are born clean slates and their biology, environment and experiences form who they will be, what they are or are not capable of.
No one wants to excuse or minimize or mitigate for JM. But many sleuths who follow cases such as this inevitably are left wondering. What made him this? Why is he like this. Why are any of the murderers murderers?
Sometimes the answer is easy. The crime driven by greed, jealousy, rage, etc. Sometimes the answer never come. But it never keeps us from asking the question . . . Why?
I agree with this. I think people can be born without a capacity for empathy — there was a neuroscientist who took brain scans of people with psychopathy and found that they had much lower or nearly absent brain activity in the area for empathy, and someone linked a fascinating article by Jennfier Kahn about children with suspected pre-psychopathy in another thread, and some of these kids were already harming siblings or animals with no understanding or remorse.
But that article mentioned that, while a large number of violent criminals are psychopaths, as many as 50 percent of of people with signs of psychopathy go on to lead productive, non-violent lives as business leaders, scientists and so on. In fact, the doctor who did the brain scans found he himself matched the medical profile, and in examining his own life found he had several psychopathic tendencies. The difference, he believed, was how he was raised, and the doctors studying pre-psychopathic children felt the same way. Children with these traits who grew up in a peaceful, loving environment where they got a lot of love and guidance from their parents and psychological help were much less likely to turn violent, although a few still did. Children who grew up with cold, distant or abusive parents and in violent or neglectful homes were much more likely to become violent criminals, since they already had the capacity for violence and nurture "pulled the trigger."
I bring this up because I believe, if JLM is indeed convicted of the crimes he is connected to, he may show some signs of being a psychopath. Complaining about his clothing and sleeping situation when accused of kidnapping a murdered girl shows an incredible lack of empathy or remorse. If his friends are telling the truth, that after the sketch in the Fairfax case was passed around he changed his appearance, that also shows a lack of empathy and a concern with being caught imo — especially since they said he never really reacted when they mentioned he looked similar, just kept quiet. In fact, just having a "type" points to a lack of empathy, since he did not know these women. It indicates that he either saw them as objects or just didn't think their lives were as important as his need to demonstrate his power over them. All of this is IMO, of course.
In my opinion, many serial killers are likely psychopaths. Anyone has the capacity to commit violence if not the predisposition, but repeated violence is a whole different level. I doubt anyone with "normal" psychology could or would kill multiple people over a period of time, especially strangers. I don't think this absolves them of responsibility at all — unlike people with, say, violent schizophrenia or psychosis, they have the capacity to know right from wrong, they just don't care. Even if it did absolve them, someone with psychopathy who had a history of violence, especially murder, would need to be imprisoned indefinitely to protect innocent people, imo.
ETA: The sources I reference:
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http://www.nytimes.com/2012/05/13/m...ear-old-a-psychopath.html?pagewanted=all&_r=0
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http://www.amazon.com/The-Psychopath-Inside-Neuroscientists-Personal/dp/1591846005
Also, some of these restaurants that turn into bars later- it's easy to eat dinner there late so that you're already "grandfathered in" by the time they start carding. 
