. >>> we want to bring in law enforcement analyst and retired atf math charge jim cavanaugh. good to have you with us this morning. i want to pick up on the point that matt was talking about, about the identity of the attacker. walk us through, through your experience how do you begin to piece together the identity of this attacker. more importantly, when do you get to the point to say we are comfortable there is not another imminent risk? we have seen in the past many of the large scale attacks in europe happening in multiple cells, whether it was the brussels airport attack, paris, istanbul, several rounds of attacks. how do authorities this morning wake up and assure the public that there isn't yet another imnep attack? >> great question. well, you have to go to the residence of the. bother, to his materials, his family, neighbors, friends. you have to go to his electronic devices and you have to do a psychological autopsy, everything about him. you have to to know what he was thinking in the months ahead and you piece that together by his associates, coworkers, classmates

jim cavanaugh is a retired atf special agent in charge for over three decades. occupation that i don't know how you did was arrive at something like this, 19 souls are gone. a happy occasion. your job is to examine what's left. examine all the clues and signatures you can to figure out who did this. >> right, brian. we trained police worldwide, atf did, on how to do these bombing investigations we've trained the uk police, we trained police all over, because we did so many bombings. we used to have a lot of bombings in america. we had bombings of union strikes, criminal bombings, klu klux klan attacks, boyfriend/girlfriend murders. they've subsided to be mostly terrorist related, but for many years, we had many large bombs all over the country for different reasons. but we talk about satellite spinning and the great work of our intelligence officials and the president being briefed. that's so important to understand the global connections, but really at the granular scene, we go in there and we get the guy's wallet from his blown up, bumped out pants and we pull

joining me now, jim cavanaugh. rse an msnbc enforcement analyst, retired atf agent with a lot of experience, and as promised, back with us prosecutor joyce vance. jim, your view of the obstruction issue, and whether if at a certain point there is enough blunt public talk from this person linked to the inquiry whether some guidance or some rules have to be publicly set? >> well, they do, ari, absolutely. this is a blockbuster statement by the president, in my view, given the federal statute on obstruction and interfering with any agency's official proceedings. joyce can elaborate on this. but she knows. and i know joyce. and we work together. and i would be in her office early in the morning arguing that we needed an aggressive investigation on this set of fax. look, you have the president saying he fired the director of the fbi for the only reason on earth that he could not fire the director of the fbi. he could have had any other reason on earth, any reason but that reason, because that reason obstructs the investi

earlier i spoke with retired atf special agent in charge jim cavanaugh and asked what the police should be focusing on this morning. >> they're focusing on the bomber. uk police say they have over 400 officers on this and they're going to be very aggressive. likely they are conducting a search, a search warrant over there they call it a queen's writ to go in the house of the bomber and get everything out, electronics, certainly bomb making materials if there, and try to walk this back, see who he is and what he's about, what exactly the motive is. and if it turns out to be terror then who are his accomplices or people who supported him or delivered him there or made a bomb for him. a lot of answers yet that we're going to have to get unfolding in the hours ahead. >> celebrities in shock are reacting to the reported explosions in manchester expressing their heartbreak and deep concern for ariana grande and the fans attending the concert. overwhelming response on twitter sending prayers and condolences to manchester, the victims and their family. >> kristen chenoweth with a heavy heart sh

. >>> let's bring in law enforcement analyst jim cavanaugh. heart breaking story. where does the investigation go from here? >> they are focusing on the bomber, gigi, it's in full swing now. uk police said they have over 400 officers on this and they are going to be very aggressive. likely they are conducting a search, a search warrant over there they quacall it a queen's writ to go in the house of the bomber and get everything out, bomb making materials if there. try to walk this back, see who he is and what he's about, wa exactly the motive is. and if it turns out to be terror then who are his accomplices or people who supported him or delivered him there or made a bomb for him. a lot of answers yet that we're going to have to get unfolding in the hours ahead. >> there are investigators could know the identity of this attacker but are not releasing it when it comes to this investigation. you always talk about timing and target when it comes to these attacks. what does it tell you that this happened outside the actual arena in the ticket area or the foyer area, an

jim cavanaugh is a retired atf special agent in charge for over three decades. he part of your occupation that i don't know how you did was arrive at something like this, 19 souls are gone. a happy occasion. your job is to examine what's left. examine all the clues and signatures you can to figure out who did this. >> right, brian. we trained police worldwide, atf did, on how to do these bombing investigations. we've trained the uk police. we've trained police all over because we did so many bombings. you know, people don't realize, we used to have a lot of bombings in america. we had bombings of union strikes, criminal bombings, klu klux klan attacks, boyfriend/girlfriend murders. they've subsided to be mostly terrorist related, but for many years, we had many large bombs all over the country for different reasons. but we talk about satellite spinning and the great work of our intelligence officials and the president being briefed. that's so important to understand the global connections, but really at the granular scene, we go in there and we get the guy's wall

and jim cavanaugh is a law enforcement analyst. sean, you first called my attention to this about 20 minutes ago. you needily knew what it was. these steel beams that pop up from the ground here in new york city. >> yeah, those are placed strategically in the high pedestrian traffic areas specifically to stop vehicles from coming up on to the sidewalk into that area. and looking at this particular vehicle, there is one of two ways that car is up on that stand shon, either it catapulted somehow or it may have been activated, somebody perhaps saw something occurring and actually activated it while the car was passing over it. not clear exactly how it happened. but certainly stopped the vehicle there going any further one way or the other from either if it was propelled through the air, stopping it from continuing to roll, or if it was actually traveling and the stand shon popped up incapacitating the vehicle. >> we continue to learn more about how this precisely all went down. it was shortly before noon when fire officials got a call

i want to bring in law enforcement analyst jim cavanaugh who worked on explosives and it appears we do have explosives. the question is from what we know and the sort of level of mayhem this caused, what we could conclude about how difficult something like this would be to put together. >> there's a degree of difficulty. bombers like this are schooled, they can be schooled on the internet or trained by someone. in a suicide bomb, backpack, the common activity is make it antipersonnel bomb, full of nails, you know, when i was agent in charge of birmingham division, we had eric rudolph bomb the clinic, nail bomb, directional, improvised, killed a police officer. i've seen, you know, fragmentation bombs, ball bearings, nuts and bolts and all kind of devices. when you put a bomb in a backpack, you'll fill it with fragmentation. you'll have some explosive filler in there. i think the discussion you had with malcolm and ally earlier was spot on. you know, the first thing that hit me on this bombing was the timing, the targeting. you know, why at the end of the concert? it speaks very loudly

i want to bring in now to the coverings law enforcement expert jim cavanaugh who has among his many years of experience in law enforcement a lot of time working with explosives and working with extremist at the atf. thanks for being with us tonight. appreciate it. >>ness that, rachel. >> what are the other types of attacks that are in this category that you would put in this same column in terms of the m.o. that we saw here with this attack in manchester? is this like anything else? >> well, you know there are a lot of suicides by bomb. i've worked a number of those. i remember one a few years ago where a man blew himself up in a land rover outside the oppositery land hotel in nashville which is the second largest hotel in america and everybody thought it was terrorism but it was suicide by bill of indictment what we have to remember here, and that is not uncommon. people do kill themselves with bombs. there was a guy outside a oklahoma stadium in 2005 that looked like it m he been suicide with a bomb you'd say stadium full opeople of the so it does happen. but here, rachel, like you were

jim cavanaugh is one of the experts who always comes on the air with us after we're covering some event like this. jim is a retired atf special agent in charge for over three decades. jim, to shawn's point, you roll up on the scene if you're a first responder. you're not really thinking about keeping the evidence pristine. you are doing triage and trying to save lives. police respond in first, second, third wave. they're getting a little bit more sophisticated as they work from the center out, helping those whose lives can be saved. and then wondering what went on here. but the bomb guys, the explosive experts have a lot of evidence to go through now. >> no, that's right, brian. you have a lot of evidence to go through. bomb investigators have been to many, many bomb scenes, taught bomb investigation, worked in cases, bombings, remote control bomb, mail bombs, murder bomb, suicide bombs all over the country you. get there, the scene is hot. you go to the seat of the blast. you have to sweep for secondaries. that's what the bomb squad has to do to make it safe. sometimes the device is pa