CNN The Situation Room May 4, 2013 22:21:00
Some of the most important clues in the boston bombing investigation may lie inside the brains of the suspects, possible abnormalities that experts say could have predisposed them to this kind of horrific attack. here is our chief medical correspondent dr. sanjay gupta. >> reporter: in the wake of tragedy come the inevitable questions, what makes a killer? is there a switch that turns on a rampage? and why? why would someone do this. >> you can say the person's evil. i think that's 13th century thinking. i think we've moved beyond that. >> reporter: he is a criminal obviously gist. he spent mo...