Something drove Seung-Hui Cho to kill so many innocent people and then himself in the worst mass shooting in U.S. history, but could the answers lie behind his eyes, in the frontal lobe of his brain?

That part of the brain is called the orbito-frontal cortex and that seems to be the area particularly critical to our ability to inhibit aggressive impulses.

Dr. Sanjay Gupta spoke with one neurologist who has studied the brains of killers.

Neurologist, Dr. Pamela Blake never examined Cho and has no evidence of what prompted his rampage, but she did look at brain scans of 31 other killers and found 20 of them had damage in areas crucial to impulse control.

Another study found that 40 percent of Texas death row inmates also had damaged brains.

The end result is impairment in normal interactions, normal empathy and normal ways of conducting yourself in the world.

According to researchers, a number of things can damage the brain: head injuries, childhood physical or sexual abuse, even chronic stress, which can cause the brain to shrink in key emotion centers. Usually several factors all collide and will lead to an event like the Virginia massacre.

A chilling footnote: an autopsy on the 1966 University of Texas sniper, Charles Whitman, who was responsible for the largest school massacre in U.S. history up until Monday, found a large tumor on his brain suggesting to some he was physically unable to control his rage. Suggesting that his brain really did make him do it.

WBKO will continue to follow the developments of the Virginia Tech massacre as they unfold.