good afternoon. i'm jake tapper. this is "the lead" live from boston, massachusetts one block over from the scene of the deadly terrorist attack here. it's been the biggest question since the moment the bombs went off. who could have done this? within the last few hours, conflicting reports began rolling in, some claiming that a suspect had been arrested. we now know from the fbi and a number of other sources that is not the case. an official briefed on the investigation tells cnn investigators have visually spotted a potential suspect on video from the scene but we're told authorities do not know who the person is. there is no positive i.d. we expect more details at a briefing from law enforcement in an hour and will bring that

live. we've learned the identity of the third victim killed in the attack, lindsay liu. the school confirmed her identity earlier this afternoon. 8-year-old martin richard and 29-year-old krystle campbell were also killed in the horrible bombings. 178 people were injured and at least 100 have been released from area hospitals. i'm joined by john king and cnn analyst. juliet, start with you. you are a former homeland security official. what are you hearing on the latest of the developments especially when it comes to this individual who was spotted on videotape? >> essentially what you said, you know, that the idea they would have a name that soon seemed way too quick for someone in custody unless he was well known to law enforcement already or was under surveillance. right now this is exactly how you would expect an investigation to unfold. there will now be -- trying to figure out what his name is but, jake, the key is what are they

going to say at 5:00? we shouldn't second guess that. if at 5:00 we see the picture it means the case is cold and they are going to engage the public. someone rented something to him or sold him something or saw him that day. that is totally appropriate and a law enforcement fak tick, actually engage go-to public and asking what they saw. if they do not disclose the picture it will be to confirm what we're already hearing confirmed now and that they're probably close. i believe just sort of the way this probably unfolded today is news that there was a picture was disclosed, so that this person might do something that would, you know, get them under law enforcement. >> you think this was purposeful. >> i think there was probably -- i mean, there's been so many validations of the picture. >> right. >> that that just sort of comes out. it's not like anyone is trying to hide anything. the name seems sort of odd to me always from the beginning. i've been saying i really think it is important that the only goal we really all collectively

should feel about, feel for, is that the arrest is really clean and that the case is really strong. and then that will be a good thing. >> john, we know some of the videotape law enforcement is using is from lord & taylor though lord & taylor will have no comment but sources have told us that that they -- the cameras picked up and law enforcement had been studying this visual. what else do we know about the location of this, not the location but the spotting of this individual on surveillance video? >> let's address what we know and then we can talk a little bit about what the source of confusion is. overnight they had a breakthrough in video analysis and i'm told largely from the lord & taylor surveillance and there are several cameras outside the department store, several others inside. i was told by several sources video from the lord & taylor department store was the breakthrough. they identified somebody delivering, dropping, placing the package, the second bomb at the second explosion location and used video enhancement, also

video from a boston television station i'm told was part of that process. from that i was told they had a clear identification of a suspect and are pursuing that from there. i also did speak on the record with the boston mayor who confirmed it was the lord & taylor breakthrough. he said there had been significant progress and would not go further. as to the confusion and this is very frustrating on this day. fran townsend our national security contributor who has excellent sources in the federal government had a federal source say an arrest was made. i had a boston police source. the associated press said there was an arrest. others said an arrest was imminent. not saying that to spread the blame. it is very frustrating in a breaking news situation when that happens but, clearly, now we have on the record from the justice department, fbi, and boston police that no arrest has been made. clearly, there is a significant turn in the investigation and, clearly, at this point it appears that people who have been reliable sources in the past 48 hours were either giving us inaccurate information or got

ahead of themselves on something and that is what we're trying to piece together. >> thank you so much. we'll turn now to the former secretary of homeland security tom ridge. he joins me now from washington, d.c. secretary ridge, thanks so much for joining me. what is the latest in the investigation as far as you know from your sources? certainly you are plugged in to law enforcement. >> i think i'm going to wait until commissioner davis holds his press conference at 5:00. i think there is undeniably a great desire for not just the press but the americans to know an arrest is imminent. at the end of the day there are conflicting reports and i think we'll probably get some clarity when the commissioner speaks to us at 5:00. >> what types of things -- knowing what we do now, which is that there is a tremendous effort by law enforcement authorities to comb through all images from the area around copley square both from the lord

& taylor surveillance camera, other surveillance cameras, law enforcement has been reaching out to individuals who were there, having them share their photographs, share their cell phone and iphone videos. what kind of technology is available to counterterrorism officials, to law enforcement, to enhance these visuals? i know we have an idea from movies that one can just enhance these images to a remarkable degree. is that pure fiction or is there something there that law enforcement can actually do when it comes to that technology? >> jake, i think you're on to something. first of all, the technology is dramatically improved year by year. and the opportunity to take a granular digital photograph or videos and break them down for much clearer pictures is just part of the scientific approach that the investigators on the scene have taken. it's very incremental, very methodical. think if you would of those huge jigsaw puzzles with a thousand or 5,000 pieces.

you spread all over a table and you start trying to put those pieces together bit by bit. and it's pains taking work and every once in a while there may be one piece of the puzzle that jumps out at you and that is maybe what commissioner davis will talk about that leads you to putting a more complete picture together. so in large measure, it has been since 9/11 that we've continued to develop these technologies. at the end of the day it is grunt work. investigators, police, local police, state police, fbi. scientists at various labs looking at the forensic evidence associated with the explosive device with remnants of the explosion. all in all you have a very comprehensive, holistic approach but it is very incremental. minute detail. if a major lead comes from a video we are very fortunate. the other thing i think it is important to mention, in the midst of this horror and ghastly evil there is some positive news. and when you read about how the first responders reacted

immediately, the police, the fire, the emergency service personnel, how triage was done immediately, how obviously at the point of the serious injuries and deaths, the decisions were made to distribute the seriously wounded to multiple hospitals. they did triage on the scene, they'd obviously been preparing for a mass casualty event. this speaks for growth and maturity frankly of the department of homeland security which is a federal agency but you can't secure the country and you cannot become resilient inside the beltway. you need partners. you need the state and the local. when you have training exercises, give them fedd eeral grants, share information, that is the physical and personal infrastructure. there is also a psychology to resilience. as you report and others have noted, people went to the hospitals, not being asked, we know blood is needed. people going from one side of the street to the other to help out. that speaks to a very resilient, compassionate and caring

country. and it makes all this horror -- that is a pretty positive sign in the midst of all this horror. >> no doubt the first responders were quite heroic and saved lives with running into the smoke and just away from it. absolutely. we know also of course secretary ridge that the london marathon, they are now taking extra precautions because of what happened here just a block or so away in boston and into the very near future we're going to see huge crowds at the indy 500, the kentucky derby. how do we as a society and how does the federal government keep people safe at these massive events? >> well, you've asked the impossible question. there is no good, total answer. you can reduce the risk of an incident but you cannot create a fail/safe environment. certainly not along a 26-mile plus path that goes through commercial, residential areas. it is difficult enough at an ampitheater, race track,

gymnasium, or stadium. i think we'll see in the future perhaps additional security but there are certain venues that it is very, very difficult to maximize to a point where you're fairly competent that nothing can happen and certainly a marathon is one of those kinds of events. as you and i both know every day in this country there are multiple venues where hundreds if not thousands if not tens of thousands of people for social, political, athletic reasons show up. so there will be lessons learned based on this tragedy. there will be probably a little more inconvenience down the road about -- i read with great interest that the london marathon is going on. pittsburgh is having a marathon next week. they have not canceled that. they're encouraging the runners to go. there was an interesting piece by tom friedman today in the "new york times." he basically if i could paraphrase it says, you know, terrorists live in caves. we don't live in caves. we don't live in fear. we're not going to hunker down. we're going to keep doing what

we've done for a couple hundred years, enjoy the bounty and liberty that is ours. we'll ramp up security. it may be more inconvenient but we make no mistake. we accept this as a global scourge. we've been waiting for something like this to happen. it did. we're far better prepared to respond and recover. i have great confidence in the investigative abilities of the federal, state, and local police to find an answer to this in the near future. >> all right. former pennsylvania governor, veteran, and secretary of homeland security, tom ridge, thanks so much for joining us. please stay with us. we'll be right back. ♪ ♪ this is a stunning work of technology. ♪ this is the 2013 lexus es and the first-ever es hybrid. this is the pursuit of perfection.

aaah! aaaaah! theres a guy on the window! do something, dad! aaaah! aaaah! what is happening? they're rate suckers. their bad driving makes car insurance more expensive for the rest of us. good thing there's snapshot from progressive. snap it in and get a discount based on your good driving. stop paying for rate suckers. try snapshot free at progressive.com. are you still sleeping? just wanted to check and make sure that we were on schedule. the first technology of its kind... mom and dad, i have great news. is now providing answers families need. siemens. answers.

ó?

??çó as if the national psyche had not been damaged enough by the terrorists' attack here in

boston a new panic in the halls of our most vital government institutions today. letters sent to president obama and mississippi senator roger wicker have initially tested positive for ricin, a deadly poison. we should point out the initial tests are sometimes inaccurate but they did create an evacuation in the senate today. i want to bring in chief white house correspondent jessica yellin at the white house and chief congressional correspondent dana bash on capitol hill. jessica, let's start with you. what is the white house telling us about this letter to president obama? i know it didn't actually arrive at the white house, but what do we know about the substance in this letter? >> jake, well, we know first of all that they are -- the fbi and the secret service are continuing to investigate and conducting further tests on this letter. they say that they had protocol set up for exactly this kind of incident and this is the exact standard incident that they, you know, protocol they set up

after 9/11. the letter contained a message that was parallel to the same message that was in a letter sent to senator wicker. it said, quote, i am -- it said to see a wrong and not expose it is to become a silent partner to its continuance. i am k.c. and i approve this message which is allegedly a comment on health care and providing care in general and so it could provide something of a lead for investigators. they believe they tied it to memphis, tennessee, but nothing beyond that. they are looking for a third facility, the possibility there were traces of ricin at a third facility. but the emphasis here from the white house, jake, is that nothing reached the president. no one was injured. and at this point they don't see a connection to the boston attack, but, of course, at this

early stage they also can't definitively rule that out, jake. >> and as of course we know ricin obviously there is often a false positive for the first test. >> right. >> congressional correspondent dana bash chief congressional correspondent, quite a day on capitol hill. explain what happened there today and what is the atmosphere? is it as nerve wr-racking as after 9/11 when the anthrax letters were sent? >> reporter: not quite that nerve-racking. there was certainly a lot of anxiety then but certainly much more palatable than it has been for years here on capitol hill. i should note just to sort of follow up on what jessica was saying as far as i'm told there had been no arrests, nobody in custody who may have been responsible for these letters being sent to senator wicker and to the president, but law enforcement sources as well as one senator say that they do believe there is somebody they're looking into who may have been harassing senator wicker in the past. now, mentioned the fact that there's been a lot of anxiety.

if you look on the senate floor as we speak, the work is going on. life is going on. there is a very critical vote happening right now on a bill or amendment to expand background checks for guns. we expect the bipartisan compromise to go down. there is certainly legislative drama here but much of the drama was about the safety here on capitol hill. for a couple hours there was a lot of tension because a hall right down from where i am right now was shut down because of a suspicious package going to senator richard shelby's office. in another office building there were two floors effectively on lockdown because of suspicious packages there. actually they were given the all clear. but it does give you the sense of how much people are paying much more attention to even questions about whether anything is suspicious around in some state offices, carl levin of michigan, they, too, issued press releases saying they had suspicious letters coming and

they turned it over to officials. you know, with going back to your initial question, jake, with regard to anthrax, definitely you get the feeling that they're saying there are no definite connections but you have that sense of anxiety you did during the anthrax attacks which were just not too long after 9/11. >> and, of course, that vote you're talking about, that is the bill from the west virginia democrat joe manchin and pennsylvania republican pat toomey. you're saying it is expected to go down. one last question for you, dana. what if anything will the senate do differently because of today's events that they weren't already doing because the anthrax scare more than a decade ago? >> well, there are some things we can already see. i believe we had some video of the fact that some garbage cans that are in and around the capitol hill complex have been turned on their side, dismantled for obvious reasons. the other thing is that the mail

facilities again are off site. mail is not supposed to come to the united states capitol. they have been closed down and people won't get mail until monday as they continue the investigation and continue to look around and make sure that there weren't any other letters that had traces of ricin or anything else as innthey're loog into what went to senator wicker of mississippi. >> we'll be back to you shortly. thank you so much. now, everyone is an expert in poison so let's find out more about ricin and how it can be used as poison. just how dangerous is it? joining us from new york is leonard cole, an expert on bioterrorism and on terror medicine. and of course we still have with us former department of homeland security secretary tom ridge. i'll start with you, mr. cole. just explain to us, what is ricin and how difficult is it to make it? >> ricin is a by product of the caster bean which is a naturally

found plant. we derive catsor oil from the catsor bean and in the course of processing one of the unused by products is ricin. when ricin is purified and you have to have some laboratory knowledge to do this, purified and produced in a light powder form that can float and be inhaled, it can be highly dangerous, lethal. one or two grains of salt would be the equivalent size of the amount of ricin that could be lethal to a human being if the person iningests or inhales it. >> incredible. so how common are ricin attacks in the u.s.? >> the actual attacks, very, very rare. there had been instances when some white supremacists' groups had either had plans to or actually did produce some ricin and they've been stopped. it has not been a generally used bioagent, you know, first of all it is a biological agent insofar

as the castor bean as a plant, it is a biological material. we generally think of bioattacks as coming from bacteria or fungi like anthrax or small pox. but ricin is easily available in terms of the potential for making it into a dangerous material and weapon but it has not been used extensively by any means. >> what are the symptoms if exposed to ricin? it's a series -- first of all, the effects of ricin, the toxin, is effectively a neuro toxin. it begins to shut down your nervous system. something like seran the agent used in the japanese subways in 1995. what happens is you begin to get symptoms, unpleasant for sure. dizziness, nausea, tightness. you're seeing it on the screen. fatigue, and actually after a

while if it gets more severe you have trouble with your coordination and neurological capabilities. ultimately death. >> horrifying. so, secretary ridge, there is an uncomfortable dejavu sense about all of this. we're told that there is no connection, none has been established between the terrorist attacks here in boston and the ricin letters. but it does have an echo of what happened after 9/11 with those anthrax attacks. what are your thoughts when you hear about these ricin letters? >> well, you use the right word. it has a resounding echo in my mind and in my heart because i think i was sworn in on october 8th. we had dealt with the trajectge of 9/11. there had been reports of anthrax. the following weeks there were additional reports of anthrax. your correspondents have demonstrated once again we've learned from those lessons and the experience of 9/11 and the anthrax. what have we learned? they sort the mail not at

congress anymore. not at the white house. it is sorted at a separate facility. somebody talked about new protocol at the white house. was there new protocol established to deal with the kind of terrorist attack that occurred on 9/11 but different protocols dealing with intoxication. so every step along the way when we've experienced and confronted the horror associated with these attacks there have been lessons learned and they've been applied. which means as a country as terrible as these things are we listen, we learn, we become better prepared, and therefore we become a much more resilient country. so to that extent, the only thing i wanted to just compliment you on is frankly i think it was good to have a bioterrorism expert on. i could say the same thing and people wouldn't necessarily view me as a credible source but one of the real challenges for the media and journalists at a time like this is to make sure people understand the nature of the attack, the nature of the poison. it's serious, absolutely. let's not be breathless about it. it is not a con teenagean.

there are certain symptoms and right now it seems to be a condition that is well contained. we'll learn more in the next few hours and weeks but i think it is very important for the public generally to understand the nature of these attacks. >> all right. secretary ridge, stick around. we'll come back to you. we're still waiting on that news conference on the terrorist man hunt here in boston coming up. we'll bring it to you live plus, next, get more on the latest on the investigation. stick around. girl vo: i'm pretty conservative. very logical thinker. (laughs) i'm telling you right now, the girl back at home would absolutely not have taken a zip line in the jungle.

(screams) i'm really glad that girl stayed at home. vo: expedia helps 30 million travelers a month find what they're looking for. one traveler at a time. expedia. find yours. at od, whatever business you're in, that's the business we're in with premium service like one of the best on-time delivery records and a low claims ratio, we do whatever it takes to make your business our business. od. helping the world keep promises.

welcome back to cnn. i'm jake tapper. i want to go to capitol hill where our senior congressional

correspondent, chief congressional correspondent dana bash has breaking news. what's going on? >> reporter: we mentioned earlier life is going on here on capitol hill and people who have been pushing for new gun laws to curb gun violence just suffered a big blow and those people include those over at the white house including the president who really pushed for new laws. the bipartisan compromise to expand background checks on guns just failed to break a republican filibuster. the vote was 54-46. technically, six votes short of the 60 needed. it is a huge loss and a huge disappointment to the democratic senator from west virginia, joe manchin, the republican senator from pennsylvania toomey, both of whom had an a rating from nra and wanted to go ahead and do this they said to change things post newtown but couldn't convince enough senators particularly republicans to go along with it expanding

background checks just to gun shows and internet sales. too many senators said they didn't think this was the right way to go. this is probably the closest they thought they could come to changing gun laws. there will be other amendments but in terms of a real prize for those looking to expand gun restrictions this was it and it didn't happen. >> how much of this was because of principled opposition to the amendment and how much an issue of risk/reward. in other words there was very little potential reward because it was probably never going to pass the house of representatives even if it was going to be voted on in the house. for some senators it might not even have been worth the risk of voting for it since it wouldn't have become law. >> reporter: a great question. it is hard to know how many senators decided not to vote for it for that reason.

what tends to happen is as you get close to the magic number of 60 all of a sudden you can potentially get a whole bunch of other senators because the senators who are voting for it realize that, you know what, i might as well get on the side of a winning issue here. to your point that is exactly what did not happen here. you had gabby giffords, mark kelly of course who had been really pushing for new gun laws. they are here actually as we speak. you had newtown families going around and they just couldn't convince enough of the senators to go along with it. you talk to some of them and they argue they were too worried about as you put it the risk particularly the back lash from the nra. >> all right. thanks. i want to turn back now to the investigation into the terrorist attacks here. this is the pressure cooker type situation, the kind of pressure cooker the law enforcement is looking into. this was filled with all sorts of instruments of death that were used to kill three people and wound many others. common items in that pressure

cooker used to unleash unspeakable violence in downtown boston. now joining me from washington, d.c., tom fuentes former assistant director for the fbi and michael bouchard former assistant director of the bureau of alcohol, tobacco, firearms, and explosives. authorities are poring over these items to try to find any clues. tom, what was your first thought when you heard of the materials used to create the bomb? >> it sounded like a fairly simple bomb. using a pressure cooker is like creating a pipe bomb in essence. you put the material inside the cooker, close and lock the lid. as the explosive material burns and burns very quickly the gases expand and at a certain point it is too much pressure for the lid and the pan blows up. you can insert in that debris and shrapnel and other items but it is essentially not any different than taking a long pipe and capping both ends with an ex-ploes alternative the

middle. it is just a little different thing. it is a store bought thing that seals up and works very well. >> how hard would it be to transport one of these pressure cooker bombs through a crowd as big as the one around the finish line off the boston marathon? obviously it is physically not that cumbersome but is it, is there a risk of it not being stable as you are walking it through? >> it is relatively easy to transport an item like this. it might weigh ten to 15 pounds depending on what they put inside the pot. but again, it is relatively stable. if you use the low explosives such as black powder, smokeless powder, something along those lines it would be relatively stable to transport. not much of a risk for the person carrying it. >> and, michael, staying with you, as deadly as the device was, it does sound pretty crude. how difficult is it to put something together like this? >> these are very easy to put together. you don't see bombs in pressure cookers very often. however, for more than 20 years i've seen this kind of

information on the internet about how to use one. you just don't see it used very often. again, it doesn't take much experience. you just need an oxidizer or fuel power source and if you use a timer or some other type of action command to detonate it, it is relatively easy, all available on the internet. >> tom, these sorts of bombs have been used by everyone from the would be times square bomber to the terrorist on the tiers of afghanistan, pakistan, i've heard from many troops over there that there are lots of pressure cooker bomb eers and h difficult would it be for anyone to build this kind of thing? >> just go to the local retail store and buy it. you get a coupon and save money doing it. also when you're going through a check point if somebody looks inside the bag you could tell them you're on the way to open a soup kitchen or something. it doesn't have the appearance of a pipe bomb necessarily.

it looks like a harmless device. the main reason is maybe as land mines that you can put that in the ground and with the pressure, you know, with it sealed it avoids environmental contamination and keeps the contents dry and ready to explode and protects the inner workings of the bomb. that's been the more common reason for doing it in the past. with all the publicity this week, it may gain popularity here as well unfortunately. >> thank you so much. >> you're welcome. thank you. >> from iraq to afghanistan to peaceful downtown boston the marathon terror attack is underscoring the danger of these i.e.d.s within our own shores. cheap to make. hard to find. able to cause mass casualties in a large crowd and kill in shocking fashion.

it's a legacy of the war on terror. improvised explosive devices known as i.e.d.s have wreaked havoc on u.s. forces in iraq and afghanistan tearing through armored vehicles and in afghanistan amounting to half of all u.s. troop deaths. with the devastating bombing at the boston marathon the threat that is overseas has come home. >> it is an enduring threat. >> this lieutenant general runs the defense department's counteri.e.d. operations and last year said, quote, we're dreaming if we think this threat will leave us after the wars in afghanistan. since 2011 there have been more than 10,000 i.e.d. attacks in over a hundred countries. >> 40 different networks were responsible. in the future it is estimated home made bombs will become the weapon of choice in the u.s. >> i.e.d.s are the biggest

single threat we have to our security in the nation. >> he ran the homeland security department bomb prevention unit. >> the capacity to construct and build an i.e.d. is really very small in terms of the level of engineering or technical background and the materials are widely available. >> reporter: a research center at the university of maryland says there have been 44 i.e.d. attacks in the u.s. since 2001. in 2011 a white supremacists crafted one with layers of shrapnel and rat poison, a nasty bomb which would have caused those who survived to bleed to death. his target? a parade marking the martin luther king holiday in spokane, washington. luckily the bomb was discovered 40 minutes before the event and tragedy was averted. in 2010 a plot by a home gronemus limb terrorist to detonate a car bomb in times square was also thwarted. the cost to counter the threat is in the billions but most of the money goes toward protecting

troops. leaving many civilians gathered in large groups exposed. >> our budget is miniscule. when i was the assistant secretary back at dhs we created an office of bombing prevention. annual budget $20 million a year when we started off. today it's about $11 million a year. it's probably going to be cut further. >> it would not even be enough to triple the budget, he says. a high price for an explosive that costs only a few dollars to make. we continue to get new information on the investigation into the boston terrorist attacks including specific details on one man that authorities want to talk to and what he was wearing the day of the bombings.

♪ (train horn) vo: wherever our trains go, the economy comes to life. norfolk southern. one line, infinite possibilities.

i'm jake tapper live in boston. you're looking at live pictures of the crime scene with investigators going around the area. just recently president obama addressed the boston terrorist bombings on the south lawn during an event with the wounded warrior project. take a listen to that. >> you know, we obviously meet at a time when our thoughts and prayers are with the people of boston. our hearts are with the families of the victims and now we send our support and encouragement to people who never expected that

they would need it, wounded civilians who are just beginning what will be i'm sure for some of them a long road to recovery. it is a road the remarkable warriors and athletes here know all too well. and as a consequences are going to serve for all of the families as well as all americans' continued inspiration. >> president obama will visit boston tomorrow. cnn will have full coverage of his arrival and the interfaith ceremony and he'll participate. i want to talk to fran townsend on the phone. she has been following leads all day. thanks for joining us. all the agencies involved in this investigation at the local level, federal level, how does that complicate an investigation or is there seamless cooperation? >> i can tell you in all the terrorism investigations i've worked what you hope for and work toward is seamless coordination and a single

investigative plan and that never happens. different investigators following different leads give different weight and credibility to it and so they have to work through what are their highest priorities? how valuable is the information and what are the next steps? that they're working through that doesn't mean there is conflict. there is sort of a natural process by which they're kind of -- their elbows are up and they're working the details. these are smart people working way long hours and sometimes come at it from a different point of view particularly between the feds and the locals. >> fran, we know there is an individual spotted in surveillance video at lord & taylor, another video possibly from a local television station, perhaps others from people in the crowd. there's been a lot of efforts at crowd sourcing. what do we know about this individual?

>> this is somebody that all the law enforcement sources we talked to indicate they are very interested in. they've looked at these videos and indicated they see these individuals as a suspect that it is something they want to talk to that they've seen in the images. the person place go-to package before the bombing takes place and so of course this is a person of high interest. we shouldn't view the pictures and videos in isolation. what they're trying to do was remember when we reported early this morning that they found the cover from the pressure cooker on the roof of a nearby building. they're going over that to see what forensic information they can find. is there a latent fingerprint, what sort of bomb and technical information? they'll try and put that all together to identify that individual and determine his importance. is that the bomber? is that a suspect? is that a victim? that is the kind of information they're going through now and they want to do it.

it's a very chaotic environment is the impression i have. they want to do this in a deliberate way and build the best possible case. >> fran townsend cnn national security. thank you very much. what goes into making a pressure cooker bomb and how could that information provide clues on what is behind the attack? we'll take a closer look plus of course still waiting on the news conference on the latest into the investigation. stay with us. we'll bring you that live as soon as it starts. ng work of te. ♪ this is the 2013 lexus es and the first-ever es hybrid. this is the pursuit of perfection.

...and we inspected his brakes for free. -free is good. -free is very good. [ male announcer ] now get 50% off brake pads and shoes at meineke. welcome back to "the lead." i'm jake tapper live in boston, moisture. they are looking for the virtual fingerprints of a terrorist. right now agents at the fbi lab in quantico, virginia are trying to rebuild the bombs that killed three and maintained so many innocents at the boston marathon. investigators have found the twisted top of a pressure cooker on a roof of a local building. shredded pieces of what could be a backpack and metal ball bearings. whatever is missing could be key. tom foreman is in the virtual studio with a look at the police work that could crack the case wide open. hopefully at least. tom? >> certainly, jake. what they're really looking for, what is missing is a link between that and activity in this crowd.

today tremendous emphasis on images like this one from a local tv station showing that pack sitting in front of a railing with people behind it. we've had a lot of talk about that. much of the focus today on another set of images or video captured by a security camera on a lord & taylor store across the street. this is the nearest camera to the scene of that second explosion where that package was. let me bring in my model here and show you what i'm talking about. this the model. i'll rotate it so you can see. lord & taylor is right here, this yellow building. you can see the two explosions. look at the detail. that camera we've been talking about all day is that it right there. that little blue marker shows where it is. there is the explosion right across the street. so they would have a very clear line of sight if that is the camera we're talking about. then you can see down to the other end where the other explosion occurred. the simple truth is, jake, if they have a link that shows a human being at this site they can use that video to see if they can hook into the other site and all of that will lead

not only to the explosion that we talked about so much, but that physical evidence you were just talking about. yes, they found a lot of things right now. they have what they believe to be the backpack that was carried in. this some of it was found on a roof top as we predicted might be yesterday and some of the ignition devices. if you take all of the activity on that map and what might have happened there and you can connect it to this, then you have not only visual evidence but physical evidence that can lead to an arrest and maybe a solid case. >> tom foreman in our virtual studio it is unclear if a suspect or suspects will be arrested and brought to court. lots of questions remain about how the process would work. let's bring in david kelly who prosecuted the 1993 world trade center bomber and acted as colead prosecutor of american taliban john walker lind. thanks for joining us. this would obviously be a very high profile case.

what are the difficulties in prosecuting a case like this? >> you've been hearing today about the collection of evidence. it sounds very interesting on tv but trying to translate that and convert that into admissible evidence in a courtroom can be quite challenging. so while it sounds fairly easy to put together and something like a csi show it is much different when you get into the called ron of the courtroom and having to actually use the rules of evidence to get that material in front of a jury to be considered as evidence. >> of course it's possible that the suspect or suspects might not be american citizens and in that instance what changes? >> it doesn't really change. if the person is apprehended here whether a u.s. citizen or not they'll be treated under the u.s. federal criminal law. it becomes challenging if the suspect has left the country. then we're dealing with two things. first we have to apprehend him or her. we have to follow the different

extradition treaties and procedures in that country to apprehend and get that person over here. likewise if there is evidence that can be found overseas there is going to be certain challenges there in terms of collecting the evidence in accordance with the rules of evidence and criminal procedure so that we can then get it into a courtroom and use it in front of a jury here in the u.s. >> you're saying that this person definitively would be tried in a federal court but is it not possible that the obama administration unlikely but possible that they would choose to designate him an enemy combatant prosecute him in military court? >> to get into that discussion now is to get way ahead of the situation and a lot of speculation and conjecture. cases like this have been made countless times. you look at the world trade center case, many other cases have been done successfully here through our criminal justice system and my guess is that is the way it is going on this one as well. >> thank you so much. david kelley, i appreciate it.

we're just learning that president obama will give a statement on the failed gun control amendment that will be in the rose garden at 5:30 p.m. eastern. we'll be right back. [ dog ] you know, i just don't think i should have to wait for it! who do you think i am, quicken loans? ♪ at quicken loans, we won't make you wait for it. our efficient, online system allows us to get you through your home loan process fast. which means you'll never have to beg for a quick closing. one more way quicken loans is engineered to amaze. bonkers, look at me when i'm talking to you. [ female announcer ] from meeting customer needs... to meeting patient needs... ♪ wireless is limitless. ♪ from finding the best way... ♪ to finding the best catch...

♪ wireless is limitless. ♪ all stations come over to mithis is for real this time. step seven point two one two. verify and lock. command is locked. five seconds. three, two, one. standing by for capture. the most innovative software on the planet...

dragon is captured. is connecting today's leading companies to places beyond it. siemens. answers.

welcome back to "the lead." i'm jake tapper live in boston with our continuing coverage of the investigation into the terrorist attacks in the boston

marathon. we're expecting a press conference from law enforcement any minute now to give the latest on the investigation but now is the time that i want to bring in the situation room's wolf blitzer. crazy day today. >> it certainly has been. you know what? that's what happens in these investigations. you get conflicting information. you go with what you have presuming it's accurate. then if it's not you fix it and you move on. >> there's obviously some break in the case that we know of today. some surveillance video of somebody who law enforcement wants to speak with, somebody who was there, has not been designated as a suspect or person of interest but law enforcement wants to talk to this individual but that's all we know as of now. >> we're anxious to hear what the fbi, what the governor, what the mayor, what they have to say. i know they've delayed this news conference, supposed to be at the top of the hour. we'll see what time it happens and get the latest information from them. >> looking forward to "the situation room." i leave it in your able hands. >> thanks. to our viewers, i'm wolf blitzer in washington. we wanto