0 you are looking now at live footage of the finish line they're painting. they painted last night right near where the attacks were. two weeks and one day ago. we saw them paint it last night. it is usually painted the night the marathon ends but they had to wait until last night for obvious reasons. that's it for "the lead" today. i'm jake tapper. i now leave you in the able hands of mr. wolf blitzer who is currently in "the situation room." >> thanks very much. happening now, investigators discover at least one fingerprint among the bomb debris from the marathon attacks. it doesn't appear to belong to one of the two suspects. plus president obama renews his push to close the prison at guantanamo bay in cuba amid an alarming hunger strike involving more than half of its detainees. could you soon be seeing more nudity and profanity on your tv? i'm wolf blitzer. you're in "the situation room." >> the dramatic potentially revealing new twist in the hunt for clues behind the deadly boston marathon attacks. we're just learning investigators have discovered at least one fingerprint along with female dna among the bomb debris. our national correspondent susan candiotti is in boston and has been working the story for us. she has the latest details. what about this fingerprint, susan? what are you learning? >> hi, wolf. yes, tonight that is new information that we are learning about at least one fingerprint found on a piece of the bomb debris. those two bombs, pressure cooker bombs that were used at the killer boston marathon. we don't yet have word to whom that fingerprint belongs and still waiting for more information as well on that female dna that was also found on a part of the pressure cooker bomb. remember, authorities have been trying to pinpoint that information and at last check we have no word on whether a match has been made. the question remains, who made those pressure cooker bombs? where were they made? were they tested in the united states? and what kind of training? did they get the training here? did they get it overseas? it is suspected that the bomb maker could be the elder of the two brothers but of course no firm answers on that as yet. but of course we know that for a long time the suspect who was currently being held in the federal medical facility had been talking but still trying to work out whether he will continue to talk to investigators now that he's been read his rights. wolf? >> so they now have a fingerprint and they have dna -- that's a good start in this investigation i am sure. susan, thanks very much. president obama took the podium at a last-minute news conference today telling reporters all levels of law enforcement have handled this investigation in his words in an exemplary fashion. our crime and justice correspondent joe johns is taking a closer look at how federal officials are responding to the tragedy. he's got new information. joe? >> wolf, from a justice standpoint, this case is still really in its infancy but the director of national intelligence is already heading up an effort to try to determine whether any signals were missed that could have prevented the boston bombing. with the criminal investigation of the alleged boston bombers still in full swing including the search for possible accomplices, tuesday president obama defended the government's handling of tamerlan tsarnaev, who the fbi investigated back in 2011. the intelligence community is now doing a review to determine what might have been done better. >> the question then is, was there something that happened that triggered radicalization and actual -- an actual decision by the brother to engage in the attack the way -- the tragic attack we actually saw in boston? and are there things additionally that could have been done in that interim that might have prevented it? >> reporter: one issue, whether the case presented what one intelligence analyst called a signal to noise problem that so much information is now coming in about so many potential terrorists it's becoming increasingly hard to separate what's important from what's irrelevant. some of the most important information that came was from russian intelligence in 2011 warning about tamerlan tsarnaev, which sources described as vague, but the president said things are improving. >> the russians have been very cooperative with us since the boston bombing. >> and the president's assessment of the fbi's handling of this case so far is already getting just a little bit of pushback from some republicans on capitol hill, who are saying it's just too early to reach any conclusions when the investigation isn't even over, wolf. >> they've got a lot of work to do, no doubt about that. thanks very much. much more on the boston bombing investigation. i want to turn now to syria and what president obama has repeatedly said would be a game changer in the escalating civil war. the use of chemical weapons. the president reiterated that warning today, but this time with some more conditions so is he moving that so-called red line? our pentagon correspondent barbara starr is getting new information on what's going on behind the scenes over at the pentagon. what are you learning? >> reporter: well, we've all seen the talk game changer, red line. the president has avoided specifics about what all of that means, but questions now about how much longer he may be able to actually avoid spelling it out. cnn has learned the pentagon is intensifying planning for potential military action against syria's chemical weapons facilities since a march 19th attack in aleppo appeared to show bashir al assad's troops using chemical weapons against civilians. there was classified intelligence about as many as three separate attacks. >> the use of chemical weapons would be a game changer rncht president obama says if it's proven assad's troops attacked with chemical agents the threat has escalated. >> and that means there are some options we might not otherwise exercise that we would strongly consider. >> reporter: a senior u.s. official tells cnn defense secretary chuck hagel wants detailed military options he can hand to the president if action is ordered. >> i won't speculate on those options nor publicly discuss those options. >> reporter: u.s. military sources tell cnn one option may be war ships carrying cruz missiles on routine patrol off israel could strike syrian command-and-control sites and air defenses, clearing a path for precision air strikes against chemical sites. military action could involve thousands of u.s. troops, but sources say no u.s. ground troops. the senior official tells cnn two crisis points potentially could trigger a strike. if the chemical weapons fall into the hands of terrorists or if the regime collapses, and no one is controlling the weapons. but officials stress they need more information before deciding on a next step. neighboring israel, jordan, and turkey are all being consulted on the intensified planning effort. but the big problem? right now the u.s. says it doesn't know where all the chemical weapons are located. >> you have confidence we could secure it? >> not as i sit here today, simply because they've been moving it and the number of sites is quite numerous. >> reporter: now, pressure is growing from some republicans and democrats on the hill for the administration to arm the opposition, provide them weapons. sources in the administration are telling me that will not happen because there is still a great deal of concern about who really is making up the opposition right now. it could cause even bigger problems. but what these u.s. officials will also quietly tell you is that, yes. the cia has been helping train some of the rebels in neighboring countries. wolf? >> all right. barbara, thanks very much. we'll have more on this story later in "the situation room" as well. let's get back into the investigation into the boston terrorist bombings. not everyone agrees with the president about how this investigation has been handled. republican senator lindsay graham has said bonnett ston is example of the u.s. going backwards when it comes to intelligence gathering. our chief white house correspondent jessica yellin asked the president about those comments at today's news conference. >> mr. graham is not right on this issue, although i'm sure it generated some headlines. you know, i think that what we saw in boston was state, local, federal officials, every agency rallying around the city that had been attacked, identifying the perpetrators just hours after the scene had been examined. we now have one individual deceased, one in custody, charges have been brought. >> shortly after the news conference i spoke on the phone with senator graham and i asked him to respond. >> it's not so much about blaming people as lives. we've lost eight americans in seven months, four overseas, four at home, radical islam is on the march, and we need to up our game. clearly to me the systems did not work the way they're supposed to. i'm shocked that this happened after 9/11 where people no longer talked to each other. i thought we had gotten over that. >> let's dig a little deeper with our chief political analyst gloria borger. the president is walking a delicate line. he said the fbi has done a great job since the bombings making sure there were arrests and all of that but he says, yes, it is a good idea to have some sort of inquiry, look back to see -- >> sure. >> maybe things could have been done better. >> look, he is clearly trying to thread the needle here and protect his administration from the charges that you've just heard senator graham level, which was that they were effectively asleep at the switch. they didn't pay enough attention to a bright, red flag waved at them by of all people the russians. these aren't the british or the french who came to us with this inquiry. it was, after all, the russians. so the president goes out there and says that's not the case. in fact, the fbi did everything it could. it interviewed tamerlan. it interviewed his mother. they came up empty. he went out of his way not to criticize the russians, which law enforcement has done because they went back to the russians and didn't get further answers to questions that they were asking. but he also, in threading the needle, left the door open for some kind of self-examination, saying that there are protocols, they're going to look as they should to see if there are, quote, protocols and procedures that should be put in place in the wake of this. he said, look. this is hard stuff. what he also told us is there is one question he doesn't have the answer to, which is, what triggered this radicalization? we just don't know. >> and that's what part of the investigation. >> absolutely. >> are we going to see this political tension continue between some of the republicans on the hill and this administration? >> yes. and some of the tension i would argue is healthy tension because it's congress's job to oversee law enforcement, to oversee the executive branch. and that's what they're going to do. so we know that the homeland security committee in the senate for example is going to start having hearings on this. i think they ought to do that. what you have to be careful about is that this just doesn't turn into some kind of partisan witch hunt because people want to play politics with it. we really need to get the answers to a lot of these questions and hold people accountable if they should be held accountable. but the important thing is to fix the process if anything was wrong. nobody would argue we haven't come a long way since 9/11. we have come a long way since 9/11. the question is, whether we have further to go. so they ought to do it and, by the way, the administration with the director of national intelligence is going to have his own investigation into this. he ought to do that as well. >> there will be congressional investigations to be sure as well. >> there will be and there should be. >> part of the role of congress -- oversight. lessons learned and make sure we don't repeat the mistakes if there were mistakes. >> right. thanks very much. up next two high profile candidates go at it in south carolina. the democrat elizabeth colbert busch versus the former governor the republican mark sanford. and, yes, she went there regarding the 2009 affair that led to his gubernatorial resignation. plus, prisoners on a hunger strike at guantanamo bay. now the president may finally make good on his long-time promise. he's saying once again on this day after a long period of silence he wants to take action to shut down that prison at guantanamo bay for good. we went out and asked people a simple question: how old is the oldest person you've known? 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ask your doctor about once-a-day xarelto®. for more information including cost support options, call 1-888-xarelto or visit goxarelto.com. apparently nothing was off the table when the former south carolina governor mark sanford and elizabeth colbert busch went head to head in the state congressional debate last night. colbert busch went there as one moderator commented when she slammed her opponent for visiting his mistress back in 2009. >> you and i met on a number of occasions. you said you would support trade. you said you would support the dredging, all the things we needed and, in fact, you didn't tell the truth. you turned around and did the opposite. >> in the wake of that if it really bothered you why would you write a campaign check in support of my candidacy and run for governor? >> when we talk about fiscal spending and we talk about protecting the taxpayers, it doesn't mean you take that money we saved and leave the country for a personal purpose. >> she went there, governor sanford. >> i couldn't hear what she said. >> do you think president clinton should be condemned for the rest of his life based on a mistake that he made in his life? you don't go through the experience i had back in 2009 without a greater level of humility. >> i want to be very clear, mark. nobody tells me what to do. >> except the people of south carolina's first district. >> i was in essence against ear marks before it was cool. >> this is not the end of our time as we know it. the sky is not falling, henny penny. as a matter of fact, our best days are ahead of us. >> whose voice will you carry to washington, d.c.? >> pretty feisty debate. cnn analyst and moderator of the debate last night, john is joining us right now. bottom line who do you think won? >> wolf, it was a fiery debate. i think elizabeth colbert busch won it on points. there was no knockout punch. the two candidates are evenly matched with colbert busch slightly ahead in the polls. she never had a full debate before. mark sanford has had 20 years of debates. she walked in well prepped, confident, with some real memorable one liners and more than held her own. she walked out feeling like a winner last night. >> because what he said about are you still holding it against president clinton for what happened with monica lewinsky all these years later, did she respond directly to how he came back on that issue? >> she did not, wolf. but this was one of the many surreal things about the debate. you know, you've got a democrat trying to reach out to the center quoting dick cheney to explain her support for marriage equality and the republican candidate mark sanford comparing himself to bill clinton. it was a wild ride last night. and a lot of serious issues beneath it. there's been so much focus on the personalities of the debate, the scandals of the past. but this, the constituents down in south carolina really wanted to hear about policy and they got a real, fierce fight on policy as well as personality last night. >> our cnn political reporter peter hamby is reporting rand paul the senator is going to endorse, work over the next several days, for governor sanford. nikki haley the current governor is supporting him as well. i assume that is going to help. what about the two of them down the road? is it going to help them? >> this could haunt them. remember, wolf, you'll recall the republican national campaign committee, the congressional committee, pulled its funneleding from the sanford campaign because he was seen as tainted and tarnished. but look. mark sanford's core argument is don't judge me by my scandals. judge me on my policies. he can say with some credibility he has been a consistent fighter for fiscal conservativism even before it was cool. going back to the republican revolution in 1994. that's the policies that rand paul is associating himself with and nikky haley to some level. this congressional district leads largely republican. >> there have been conflicting images on the polls. thanks very much. >> thanks, wolf. we heard it all throughout his campaign. the president vowing to shut down the prison at guantanamo bay in cuba. coming up, why the prisoners' hunger strike might actually make that promise a reality. what's going on? 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