There have been lots of studies about the effects on the human mind when people kill others.  There are the effects on soldiers in war. Or, the guards in Nazi concentration camps.  Here is a great study about the effects of murder on your brain—if you’re a criminal!  The study is kind of technical, but I found it interesting and it can lead to more info if you want to go learn more.  http://time.com/3816212/brain-murder-morality/?xid=newsletter-brief

In my own experience as a lawyer representing killers, I have made a few discoveries.  Granted, I’m not a psychologist but here they are:

1.  Most people who are able to kill others usually do it in “the heat of passion.”  They’re so upset or drunk or high, (or all of these) they pull out a gun and shoot the other person.  Murder and your brain in this case probably don’t mean much until after the event.  These kind of people are often extremely sorry for what they did and probably won’t do it again.

2.  Some people are sober and plan to kill.  An example could be a gang member who finds a rival on the street and does a drive-by shooting.  I’ve found that the shooters are usually very broken and psychologically messed up in their brains.  They’ve experienced a lot of pain in their lives that comes out as anger and violence toward others.  Certainly, murder and your brain will have a big effect on these people.  They often kill again.

3.  Then there are psychopaths.  People who are so far off the chart of normal brain activities they don’t have a conscience.  They will kill and torture people without much effect on their brain—at least, that’s what it appears to me when I’ve talked with them.

But look at the article/study.  The effects of murder on your brain have some surprising new effects that research has uncovered.