he a hero or a traitor, text or call. we'll see you tonight at 6:00. on the broadcast tonight, damage control. after the explosive exposure of our nation's spy program. tonight, new details about the source of former cia employee, and new questions about how many people have access to our nation's top secrets. the cancer risk for millions of american children undergoing ct scans each year. doctors are now sounding the alarm, raising questions about how often they are really necessary. high drama as the george zimmerman trial gets under way in florida. why legal experts say what's happening right now could have the biggest impact of all on the outcome. and life as a beatle. a never before seen look from behind the scenes from one of the beatles behind the lens. "nightly news" begins now.

>> from nbc world headquarters in new york, this is "nbc nightly news with brian williams." good evening. i'm lester holt in for brian. an international manhunt for the 29-year-old man who says he's the one who exposed the government secret surveillance program. what he told "the guardian" newspaper in a story published last week caused a firestorm of controversy over privacy and national security. edward snowden has been identified as a contractor who worked at the national security agency, and yesterday from halfway across the world, he stepped from the shadows, admitting he was the leak. and tonight, the u.s. government is hot on snowden's tail as it investigates whether or not he broke the law by sharing classified information. nbc's andrea mitchell is working the story for us tonight from washington. andrea? >> reporter: lester, good evening. they have launched the manhunt for. the 29-year-old nsa contractor, edward snowden, has turned the

massive national security agency inside out. federal agents at the home today of edward snowden's mother in ellicott city, maryland, only miles from the nsa in ft. meade. >> are you guys with the fbi? >> reporter: snowden's mother politely ducked reporters. >> please do not get in my way. thank you. have a good day. >> reporter: fbi agents showed up at his father's home near allentown, pennsylvania. >> my name is edward snowden. i work for booz allen hamilton as an infrastructure for the nsa in hawaii. >> reporter: according to the guardian, the 29-year-old was a high school dropout. he enlisted in the army, but was discharged five months later for breaking both legs in a training accident. worked for the cia undercover in geneva and says he became disillusioned. signed up for a military contractor at a base in japan. he joined booz allen ham 8 on the working in hawaii.

and a month later he copied top secret documents and then flew to hong kong to meet with glenn greenwald of "the guardian." snowden says having become hardened about the government's surveillance programs. he told "the guardian" -- >> i'm just another guy that sits in the office day to day and watches what is happening and think this is not our place to decide. the public needs to decide whether these are right or wrong. >> that's the reason why he felt so compelled to inform his citizens about the capabilities this massive surveillance program provides. >> reporter: no sign of him at his home in hawaii, and he may have left hong kong as well. >> hong kong does have an extradition treaty with the u.s. and a record of close cooperation, but extradition could take months, and china has a veto. no action can be taken until there is a charge. plus snowden still has to be found. >> reporter: a big worry now for the u.s. what do the chinese know? >> obviously we would be

concerned if some of the very sensitive information he has would fall into the hands of a foreign intelligence. >> reporter: calling the top secret leaks gut-wrenching. >> the damage that these revelations incur are huge. >> reporter: britain's foreign secretary canceled a trip to washington today to defend cooperating with the nsa. >> this relationship has been and remains essential to the security of both nations. >> reporter: but to a band of supporters in new york today, snowden is courageous. julian assange of wikileaks called him a hero. michael moore tweeted hero of the year. many agree the power of the nsa could be they're road. >> we need to make an informed judgment if we need more civil liberties protections in the law. >> reporter: why hire someone with so little foreign education to handle such sensitive secrets? intelligence officials say the real whiz kids are kids, the generation that learned computers even before they could talk. lester? >> andrea, thanks. snowden is one of the million

american granted intelligence clearances, carrying out many of the government's intelligence functions. but it does raise questions whether too many contractors are now in on the government's secrets. to get that part of the story tonight from nbc's senior investigative correspondent lisa myers. >> reporter: most us think intelligence involves spies from the cia, eavesdropping by the super secret nsa, and information gathered by the pentagon. but there is also a huge shadow intelligence community of private contractors, some of them corporations with familiar names. after 9/11, when the government failed to connect the dots, the demand for private intelligence exploded, leading to what a former official called a hiring binge of battalions of young, smart nerds. >> what once started as a process of augmenting and fighting the war on terrorism has now become an industrial system. it's an industrial system that works on a profit motive. >> reporter: near the nsa huge

complex in ft. meade, maryland there are now office buildings full of contractors. according to the government, almost five million individuals now hold security clearances. 1.4 million of them top secret. one-third held by private contractors. a check of the job website monster.com today showed 796 job openings requiring top secret clearances. the current director of national intelligence, james clapper, worked for private contractors between government jobs and his predecessor mike mcconnell now works for booz allen. many contractors have intelligence or military experience, but others are 20-something technicians like edward snowden. >> they're not motivated necessarily by patriotism. they're not motivated necessarily by a scar of 9/11. this is a job. >> reporter: while acknowledging the risk, intelligence officials argue that private contractors now are critical, even indispensable. >> the intelligence agencies

tell me that they simply could not function effectively without the personnel, technology, and expertise of these private contractors. >> reporter: a delicate balance with the nation's security at stake. lisa myers, nbc news, washington. we turn now to a story we're following closely overseas tonight. continuing concern about the health of former south african president nelson mandela, who has been hospitalized since saturday with a lung infection. nbc's keir simmons is in pretoria tonight with the latest. keir, good evening. >> reporter: good evening. those close to nelson mandela have been coming to the hospital here. for the first time his doctors say his condition is serious, and south africa's president has called on the nation to pray for mandela and his family. this afternoon, winnie mandela paid a visit to the hospital in pretoria. nelson mandela's former wife and

fellow anti-apartheid campaigner. they were married throughout his 27 years in prison. tuberculosis weakened his lungs. doctors treating the former president describe him as in serious but stable condition. >> former president nelson mandela remains in the hospital, and his condition is unchanged. >> reporter: throughout the day, visitors have come and gone. but reports suggest only those closest to him are actually by his side, including current wife graca machel, seen here on his 94th birthday. across south africa there are prayers as well as fears. >> we love him very much. he needs to recover. >> it is time for him to go. it's time to go. >> reporter: the former president, who turns 95 next month, has long been in failing health. many people were shocked by his frail appearance in this awkward photo op last april. the father of his nation, now surrounded by family. in the fight of his life. and another member of nelson

mandela's family on her way to the hospital here, his daughter zenani, flying in from argentina, where she is south african's ambassador. meanwhile, well wishes, hopes for his recovery are pouring in from around the world, lester. >> all right, keir, thank you. meantime, also overseas, we're monitoring the health of britain's prince philip, the queen's husband, who spent his 92nd birthday today in the hospital, recovering from exploratory abdominal surgery. the queen stopped by to check on him for about a half hour this evening. buckingham palace says the prince is in good spirits. he will remain in the hospital at least through next week. in a florida courtroom, jury selection began in the trial of george zimmerman, who is charged with second-degree murder in the shooting death of an unarmed teenager last year. the killing of trayvon martin led to large protests before the arrests of zimmerman, who says he acted in self-defense. nbc's ron mott is covering the trial for us. hello, ron.

>> reporter: hey there, lester, good evening to you. february 26th last year, george zimmerman was a neighborhood watch leader at a condo complex near here. trayvon martin was staying there, and their paths crossed with deadly consequences. >> i felt his arm going down to my side and i grabbed my firearm and shot him one time. >> reporter: more than 15 months after telling police about his side of the story he shot and killed unarmed 17-year-old trayvon martin, 29-year-old george zimmerman is now on trial for murder. >> i can tell you as a family, we're very confident in the outcome of the case, and very confident that the state will not be able to meet its burden. >> reporter: six panelists shown from a pool of 500 to serve on the jury. a process that could take weeks as attorneys wade through stacks of questionnaires. >> the defense wants white jurors who love their guns, maybe victims of a crime. and the defense wants those who don't want vigilantes walking around with guns in their pockets.

>> reporter: zimmerman has pleaded not guilty. his attorney says he acted in self-defense after being attacked by martin. >> we are -- >> trayvon! >> reporter: the six-week period between the shooting and zimmerman's arrest sparked protests here and around the country, with critics charging race was a factor in the case, arguing police would have been quicker to make an arrest had the victim been white. >> all of these issues snow balled into a larger narrative about race that i don't think was really part of the story when trayvon martin died. >> reporter: martin killed less than an hour seen buying candy and iced tea from a convenience store. the encounter between martin and zimmerman could be heard on a 911 call. >> so you think he's yelling help? >> yes. >> what is your -- >> just -- there's gunshots. >> you just heard gunshots? >> yes. >> how many? >> just one. >> reporter: today, martin's family asked for peace and justice.

>> we are relieved that the start of the trial is here with the jury selection, as we seek justice for our son trayvon, and we also seek a fair and impartial trial. >> reporter: once the jury is seated, the trial is expected to run anywhere from three to six weeks. george zimmerman's attorney said it's too soon to know if he will take the stand in his own defense. >> all right. ron mott, thank you. we want to note here that george zimmerman has sued nbcuniversal, the parent company of this network for defamation. the company has strongly denied his allegations. there is a lot more to tell you about as we continue tonight. doctors sounding the alarm about ct scans and cancer risks for millions of american kids. later, an inspiring father and son breaking barriers and helping a lot of folks achieve what was once thought to be impossible.

our health news tonight involves a new warning for participants about children

undergoing multiple ct scans to help doctors diagnosis medical issues and the risk developing cancer later on in life. as summer rapidly approaches and kids are out of school, doctors will see the usual increase in injuries from kids playing outside, and oftentimes that means a ct scan is necessary. now doctors are starting to take a closer look at how often kids get them, and the effects of all that radiation. we get our report tonight from chief medical editor dr. nancy snyderman. >> reporter: 5-year-old dajon frazier is having a ct scan today. his mother is following up on a complex ear and eye condition, and this scan is the best way to make the diagnosis. >> only thing my concern was really more so than anything was just to make sure he was all right. >> reporter: while ct scans are invaluable, there is also a risk. unnecessary exposure to radiation can be damaging to growing children, and repeated or high dosages may increase the risk of cancer later in life. researchers analyzed data in

children under the age of 15 who had ct scans between 1996 and 2011. they looked at the frequency and the level of radiation dosages, and estimated that of the four million scans performed each year, more than 4800 children could develop future cancers. >> the largest increase for abdomen cts, especially in older children, and this is worrisome because abdomen ct has the greatest radiation exposure and the greatest cancer risks, especially in girls. >> reporter: hospitals across the country are making efforts to reduce radiation exposure for their smallest and most vulnerable patients. dr. shireen's team at doctor's medical center in washington, d.c. has been able to reduce the number of ct scans by about 30% in the past two years by carefully evaluating a child's risk based on injury, illness, and medical history. >> we look at their mental status. are they awake, alert, able to talk to you?

do they recognize their parents? and then we look at a slew of signs and symptoms. >> this is his ear. >> reporter: dr. raymond dee, chief of radiology, meets with parents to carefully raise the pros and cons of ct scan. >> it will allow us to avoid procedure? other procedures as well? the risk and benefit is something that needs to be balanced. >> reporter: hospitals that don't have low-dose ct scanners can retrofit them for $150,000 to $200,000. but they have to make that capital investment. and in the meantime, if your child or grandchild needs a ct scan, ask if it's necessary, lester, how many slices they really have to image, and frankly, if there are other alternatives there are always questions. >> good questions to ask. all right, nancy, thanks very much. we're back in a moment with an amateur photographer who captured beatlemania as few others could.

♪ ringo starr, photographer in the beatles' first movie "a hard day's night." it turns out ringo was quite a photographer in real life as well, and he is out with an exhibit and an ebook on itunes this week with never before seen shots from his personal archive, behind the scenes at the height of beatle mania. ringo spoke to keir simmons about what it felt like for the beatles to conquer america in 1964. >> when we got to america, it was like too big, all of the music we loved came out of america. ♪ close your eyes and i'll miss you ♪ >> the new yorkers feel like they owned the beatles, that's where we landed. it was the most exciting moment. you could feel new york as the plane went over, as the plane was going over new york, you could feel the vibe, it was so great. it was like a dream come true,

we're actually there, and we're actually there at a good time. we're number one. >> ringo starr, the beatles coming to america at the top of the charts, almost 50 years ago. it was also 50 years ago that the equal pay act became law in this country. it was signed by president john f. kennedy and was aimed at eliminating the gap between what men and women earned. at that time, women made 59 cents for every dollar men earned. today at a white house ceremony, president obama noted the goal still hasn't been reached, with women now making about 77 cents for every dollar men earn. the president said this is the 21st century, and it's time to close that gap. something to think about on your next night out with friends where one is the designated who are supposed to be the responsible ones and get everyone home safely away from the alcohol. but a new study nearly 40% of

designated drivers actually drink. and 20% drink so much it significantly impairs their ability to drive. researchers say the evidence shows oftentimes the designated driver is chosen because they are considered the least drunk among the group, or because they think they have previously driven drunk just fine. when we come back, one dad's extraordinary idea to help his son and change a lot of lives in the process. >> tell me.

the big idea, brought to you by the brilliant minds and machines of ge. finally tonight, a novel idea and certainly a big idea. hire people with autism for the kinds of jobs that might fit them well and now these workers are increasingly finding themselves in demand, as we hear from nbc's stephanie gosk tonight, it is paying off for everyone. >> even it out a bit. >> reporter: for many, the high-tech world of computer game design is a mystery. for cheryl o'brien, it's second nature. she created this digital abacus for the ipad. >> pretty cool, cheryl. >> you like that? >> reporter: a computer programmer, like everyone at the nonpareil institute, has a form of autism. holding down a regular job has been a struggle.

>> i was throwing papers just to survive, doing crossing guard. >> you were delivering papers? >> yeah. >> reporter: at nonpareil, she is a full-time paid employee. the nonprofit institute in plano, texas, teaches software skills and then hires many of the students to design games, apps, and e-books for sale. >> that's really good. did you make that? >> yes. >> reporter: dan sellick came up with the idea, inspired by his son who has autism. >> we parents are desperate for answers for our kids. >> reporter: the software developer started nonpareil four years ago with a handful of students. now they have 125. >> we're very successful in technology. it speaks to all of their strengths, the quieter environment, the sound isolation. through the products that they build, they can provide a living for themselves. >> reporter: in other words, a future. >> technology can be very predictable.

people seem to be gravitated towards those kinds of areas. and so we're starting to see many companies involved in technology really tap into this pool of workers. >> reporter: the software firm s.a.p. announced a goal of hiring as many as 650 employees with autism. three years ago, alliant data hired bernie fish who has autism. >> why wouldn't anybody do this? these employees show up to work on time. they do a remarkable job. >> keep going. >> reporter: a big idea that recognizes skills in high demand and gives people with autism new hope for a better life. >> we're a family here. >> reporter: stephanie gosk, nbc news, plano, texas. >> that's our broadcast for this monday night. thank you for being with us. i'm lester holt in for brian. we hope to see you right back here tomorrow evening. good night.

nbc bay area news starts now. good evening, and thanks for joining us on this monday. customers taken for a ride, a south bay travel agency appears to have either shut down without any warning. dozens of customers are learning that the tickets they paid to buy are no good or nonexistent. >> reporter: a sign on the front door here at sunlight travel says that they're closed to file

bankruptcy. but that sign has no date on it. today, a steady stream of clients stopped by and found out the hard way that the business they had given money to book travel plans may have taken them for a ride. >> i'm very angry. >> reporter: dozens of people have been showing up. and all of them have a story. >> i lost money, and i cannot go to vietnam to visit my mom. >> tickets cancel. he said no, i pay in full. and so the airline say you need to call your travel agency. >> reporter: some clients have been coming here for year does book trips to vietnam, and this is the first time they've had problems, but these are big problems. the website is still up, but by all appearances, the travel agency has shut down and filed for bankruptcy. there is a three day notice to pay rent or quit. >> i think it's a scam. you don't weak up overnight and say i'm going to file