clock to identify the shooter and to figure out why he did it. 100 investigators are dedicated to building a profile of this mass murderer. i want to bring in joan navarro to help us through the process. he is a form senior profiler with the fbi and wrote a book on how to identify harmful people called dangerous personalities. the shooter led what they say was a secret that we may never fully understand how much of it unfolded. how do you go about building a profile on a mass murderer, a killer like this? that s a great question, wolf. you start with whatever you can gather. investigators are going to be going through this individual s clothing and look at his shoes to see where the shoes have been. they are going to go through everything in his house. they are going to go through hairs and fibers in his car.