shawn henry is msnbc's security analyst. he joins me now. help us understand what's happening when it comes to the investigation? this is a local matter, that expanded greatly, fbi and department of homeland security are involved. take us behind the scenes, give us a sense of what will be happening over the course of the next few days. >> thanks, david. i think right now there are a lot of questions, why did this happen, how did it happen, who is this shooter, and what was the motivation here. i think investigators, you've got virginia city police there, virginia beach police there on sight, you have state police, the fbi is working, providing some capabilities. throughout this investigation they're collecting intelligence to try to determine the cause. they're going to be looking through this person's social media. they're going to be looking at the opportunity to exploit documentation that he may have had on his computer system. they'll be looking for papers through his house, they executed a search warrant there, i saw this morning in med

. >>> want to bring in shawn henry, a former fbi executive assistant director. shawn thank you so much for joining us this morning. as soon as the police arrive they engage the shooter. the police chief said that prevented additional injuries and additional deaths, is law enforcement better prepared to handle these situations? >> unfortunately because of how many, how prolific these types of events are, they've been training quite extensively for the last decade on what we call active shooter. police officers are training and they are trained to clearly go to the threat as quickly as they can. oftentimes in law enforcement events there's a slow, deliberate clear when you're executing a search warrant or an arrest warrant where you know there's somebody inside who might be armed. it's very, methodical and in a case like this where you've got an active shooter, the police are trained to go immediately to the threat. they very quickly put themselves at risk. go past open doors, they go into rooms. they try to cover each other. but the idea is to get to the shooter a

we are joined by shawn henry. thank you for taking time to chat with us about this again. will they get an answer to why this happened? is there a way to look at somebody's computer profile or any way to get a sense this explains it? is there ever a fully comprehensive and satisfying answer to that question? >> alex, certainly on the back side here as ron just described the searches of the subject's home, his vehicle and social media, looking at anytime of tweets he may have put out or documentation they may uncover where he described what caused him to take these actions. on the back side of that, it will be a long drawn out process. the chief of police in virginia beach described the subject as being a disgruntled employee. that takes us to the front side. were there signs in advance that might have provided co-workers or employer or others or some indication that this person was engaged or going to engage in this type of behavior? was he isolated? did he make statements to other people at his place of employment? did he mention anything to family members or friends? on