on our broadcast tonight, deep debt. the crushing burden for millions of young americans. and what the president revealed today about his own student loans. star witness in the case against john edwards. explosive revelations today in open court. mad cow. the first confirmed case of mad cow disease in the u.s. in six years. tonight, what the experts are telling us about it. and teacher of the year. with over three million teachers in america, what makes her the very best? "nightly news" begins now. captions paid for by nbc-universal television good evening. there are warnings tonight that there's a financial timebomb set to go off if congress doesn't act. the interest rate on a popular student loan is set to double. and this is not just a financial problem for the kids who are

seeking a college education and their parents. student loan debt is now a national problem. it's now larger than credit card debt and car loans. it has exploded in a bad economy, right as millions are seeking that american dream of a college education. president obama talked about this on the road today. in fact, he did something he's never done, talked in detail about how recently he paid off his own student loans. >> we only finished paying off our student loans about eight years ago. that wasn't that long ago. and that wasn't easy. especially because when we had malia and sasha, we're supposed to be saving up for their college educations, and we're still paying off our college educations. >> the president earlier today in north carolina. nbc's john yang has more tonight about how hard it's become to pay for college. >> carried over into the second

half -- >> reporter: college graduation season is right around the corner, and for millions of students, the joy of achievement can be accompanied by dread. consider the average senior, she'll leave college this spring with a diploma and student loans totalling more than $24,000. a new life with old debts. at new york university, some students owe even more. >> i'll be facing 80 grand worth of debt when i leave. >> looking at close to a quarter million. >> it will be quite a bit, about 250,000. >> reporter: those burdens could soon grow. on july 1st, the interest rate on a popular government subsidized loan program, called stafford loans, is set to double to 6.8% unless congress acts. nearly 7.5 million students have stafford loans, averaging $11,000 each. the higher rate would cost each of them more than $5,000 in higher interest payments. >> it's not going to stop them

from going to school, but i think what we may see, they may have more trouble on the back end repaying these loans. and the default rate could go up. >> reporter: the economy has dealt students a double whammy. often their parents can't afford to help them with tuition, so the burden falls on them. with half of grads even unemployed or underemployed, paying back those loans can be hard. >> there's also an impact on the broader economy, because they don't have as much money to spend. that money, should it be put back in the economy, could help us a good deal. >> reporter: financial experts say planning how to pay for college should start early. >> you need to start figuring out what you can afford to spend when your child is just entering high school. and choose schools that have a wide range of affordability. >> reporter: to try to make sure the cost of a college education doesn't outweigh the future dividends it promises. john yang, nbc news, washington. >> let's talk about this tonight with our chief white house correspondent and political director chuck todd who's here with us in the studio.

first of all, isn't this a topic on which romney and obama agree? >> and also mitch mcconnell and other republicans, they all seem to agree this has to be changed right now, the economy is in such a place they have to do it. so what's the motivation behind what the white house is doing? well, it's called election year politics. the president today was in the swing state of north carolina, he's also now in the swing state of colorado. tomorrow he will go to another college campus that happens to be in the swing state of iowa. this isn't an official trip, but it has the trappings of a campaign event. why? he's winning the youth vote big. there's a big enthusiasm one of the reasons is because of this feeling about debt and the economy, brian. so he's trying to get back in touch with them. >> and tonight, while it may not feel like it to a lot of folks, is another primary night. >> biggest one since super tuesday, technically. actually, what you are going to hear tonight is mitt romney claim victory of the nomination. basically accepting the fact that after 43 primary nights and

caucuses, he now sort of accepts this idea that he's the presumptive nominee. he's going to use a few lines tonight, all going to be focused on president obama. he's going to say, we've seen hopes and dreams diminished by promises and weak leadership. and he's going to borrow and channel james carville, brian, it's still about the economy and we're not stupid. by the way, newt gingrich has said if he doesn't win the delaware primary tonight he will reassess his campaign. yes, he was technically still running. >> chuck todd here with us in the studio, as always, thanks. >> you got it. a late development out of washington today in the secret service prostitution scandal. more agents are out, two are resigning. two are being cleared of serious misconduct, but will face administrative action. and a fifth one will have his security clearance taken away, which will require him to leave the secret service. and veteran republican senator charles grassley raised a new spector of national security when he told a radio interviewer back home in iowa, "who knows who might be using prostitutes, the russians are famous for that, to get information out of us."

grassley says he fears this is the tip of the iceberg, and wants an outside investigator. a man who was once in john edward's inner circle, a trusted top aide during the '08 presidential campaign, is now the star witness against him in his federal trial. today that aide, andrew young, spent a second day on the witness stand for the prosecution. told a story of elaborate deception involving hundreds of thousands of dollars. nbc's lisa myers is with us from the courthouse in greensboro, north carolina. lisa, good evening. >> reporter: good evening, brian. this was the government's day through their star witness. prosecutors detailed edwards' affair, the hunt for money to keep his mistress quiet, and claimed the former presidential candidate was deeply involved every step of the way. andrew young, edwards' once loyal aide arrived ready to tell the jury that while john edwards was on the road campaigning for president, there was a frantic

search behind the scenes for money to support rielle hunter, after she threatened to go public with their affair. hunter had been fired from her job as a campaign videographer after elizabeth edwards spotted her at the official launch of edwards' presidential campaign in december 2006 and confronted her husband. young said edwards told him to approach two wealthy friends for funds to help hunter. they turned him down. then he said, they decided to try heiress rachel "bunny" mellon, who provided $725,000 in checks for what she was told was a non-campaign expense. checks written to her decorator and signed over to young's wife. >> if you believe andrew young, then i think the jury will believe that john edwards knew what was happening in terms of the money flow. >> reporter: young says five times he questioned whether the payments were legal. it all just seemed crazy. it looked and smelled wrong. but edwards assured him it was completely legal.

in his tell-all book, young said the funds were gifts, entirely proper and not subject to campaign finance laws. but today he appeared to change his tune, saying the money was to influence the outcome of the election. echoing the government's allegations that they were illegal campaign contributions. young is testifying under a government grant of immunity. one of the more electric moments came when young recounted edwards reaction to learning hunter was pregnant. he said edwards used a pejorative term and said it was a one in three chance it was his child. >> that's not the type of reaction i think many of the jurors would feel ke thehe would have had. >> reporter: young also testified that after hunter's pregnancy was reported by a tabloid, edwards begged him to falsely claim paternity of the child, telling young how he didn't want mrs. edwards to die with this in the papers. elizabeth edwards was battling breast cancer. during young's testimony, edwards occasionally clenched his jaw, rolled his eyes or

jotted down notes. his daughter kate and his elderly parents were in the courtroom. they listened intently, but didn't seem to react, brian. >> lisa myers, greensboro, north carolina tonight. lisa, thanks. it's been two years since the whole world watched as millions of gallons of crude oil spilled into the gulf of mexico. tonight the justice department has filed the first criminal charges now against a former bp engineer, who they say destroyed hundreds of text messages about the amount of oil we watched on live television gushing from that ocean floor, including one text message saying, too much flow rate, over 15,000 barrels a day. at the time, by the way, bp was publically saying the amount was much lower, three times lower than that. bp says it's cooperating with this federal investigation. the news came out late today and it sounded alarming. the first confirmed case of mad cow disease in the u.s. in six years.

this case in a dairy cow in the state of california. the government says the food supply is safe, but this discovery is raising a lot of questions. our report tonight from our chief science correspondent robert bazell. >> reporter: the cow was found at a recycling plant for dead livestock in hanford, california. u.s. officials insists it presents no threat to human health. >> this particular animal did not enter the food supply at any time. so there is no concern about that. >> reporter: bse, commonly called mad cow disease, is a fatal disintegration of the brain and nervous system. it first gained public attention in britain in the 1980s and '90s where more than a million cattle were affected, and where more than 4.4 million cattle were with slaughtered to control the outbreak. the disease is usually transmitted by a rare infectious agent called a prion.

though cases can appear spontaneously. usually the disease is acquired by eating the tissue of an infected animal. animals had been a common source of food for cows in britain. in britain, 175 people including jonathan sims got a human form of the disease by eating meat from the infected animals. health officials say milk does not transmit the disease, so the infected dairy cow does not pose a hazard. there was no mad cow disease detected in the u.s. until 2003, when a cow born in canada was detected in washington state. after that, the u.s. set up a surveillance system, although japan and some other countries for a time banned the import of u.s. beef. something officials hope will not happen again. >> this announcement should not disrupt trade, and the reason for that is, the -- we follow international guidelines. >> reporter: including today's finding, u.s. officials have found four cows in the u.s. with mad cow disease. and in 2006, the surveillance program was cut back because it was finding so few cases. consumer groups are demanding increased surveillance. but, brian, the critical take home message is, there is no

evidence of any threat to human health. >> the original isolated case. robert bazell, thank you, as always. apple reported second quarter earnings today, it was a blockbuster. $11.6 billion in profit. up 94% from the same time last year. much of this increase, they say, came from asia gobbling up iphones and ipads. by the way, they're selling over 8 million iphones per month. apple stocks surged 7%. in after hours trading. the stock went up more than $40 a share. as for the rest of wall street, it was a mixed day, the dow was up more than 74 points. the nasdaq lost almost 9 and the s&p 500 up 5. still ahead as we continue along the way on the front lines, an extraordinary look at an american fire department really under siege, fighting to save a city. and later, america's teacher of the year. and what she can teach just

about everybody about doing our best.

despite a lot of good people working hard to make it better, the city of detroit has seen more than its share of problems in recent years. and the city's fire commissioner came under fire himself this week for suggesting his department should let abandoned buildings in the city burn down, rather than waste resources putting the fires out. it is just one challenge faced by detroit's fire department, and a lot of it has been captured in a new documentary film. our report tonight from nbc's kevin tibbles. >> reporter: detroit is home to the busiest firefighters in america. >> last year alone, we had over

30,000 actual fire calls. we're in real trouble. we need help. >> reporter: the film simply called "burned" documents the lives of the firefighters charged with saving a city many have written off as dead, and they risk their lives doing it. >> there's some buildings that you come out of and you realize that the structure is designed to kill firemen. >> you don't give them the equipment they need, and you send them into situations they shouldn't be going into, they can get hurt and they can get killed. it's easy to forget that. >> reporter: a truly american story of hope, courage and camaraderie. in the face of such decline and debt, that firefighters can't even afford to repair equipment or replace leaky boots. >> i feel like a loser. can't seem to get ahead of it. every problem seems to generate another problem, and another problem, and another problem. >> reporter: in 2010, as the filmmakers were working on the

documentary, "nightly news" was covering an inferno that wiped out dozens of vacant homes in one abandoned neighborhood. along this street alone, four houses burned before the fire department even got here. the detroit fire department was confronted with 85 buildings burning out of control. >> i'm from detroit, and i never realized how it's not a typical place in terms of fire. you leave detroit and you realize, not everyone is burning their city down. >> reporter: in the motor city, fires, arson fires, have become the norm. and much of this vivid footage was taken by the firefighters themselves, who wore cameras on their helmets. >> it's not a movie about detroit, it's a movie about the guys that are going to come to your house when it's on fire. >> we need to be there for them, because they're always there for us. >> reporter: on the front lines of the battle to save the city that is their home, kevin tibbles, nbc news, detroit. up next here tonight, before your very eyes, a child goes

from birth to age 12 in a matter of minutes.

look at this latest spectacular display from italy's mount etna. red-hot lava spewing into the nighttime sky above sicily. this is the seventh eruption since the beginning of 2012. it's also been a banner year for the northern lights, because of all the solar activity. some fresh solar winds made for a spectacular light show over the south shore of lake superior in michigan's u.p. the tiny white speck moving across the lake is a freighter. if these pictures are this great over time lapse, imagine how it must have looked to those on the vessel. two web videos getting heavy circulation right now. the first could be anyone her age walking along using a cell phone. but this happened to be in china, and that's a sinkhole, the video shows to people arriving saw it happen. they tried to rescue her.

eventually they used a ladder and a rescue squad to successfully get her out. and this home video has a lot of people talking these days. an enterprising parent with the patience of a saint decided to chronicle the growth of his daughter over 12 years. he decided to make a time lapse video of his daughter lotti from infancy, through a lot of hairstyles, until we see her emerge as a beautiful 12-year-old girl, all in 2:45. the father spoke with us via skype today from his home in the netherlands. >> it appeals to a sort of soul feeling of what life is, in such a short way showing what life is, with live images like film. it's much more intense than doing it only with a picture or photograph. >> we have the entire time lapse video, and more on the interview with the father on our website nbcnightlynews.com. while in north carolina today, the president taped tonight's late night with jimmy

fallon for air tonight on nbc at 12:35 eastern time. fallon talked the leader of the free world into a guest role, a recurring bit on the show usually played by someone else, slow jamming the news, including the issue of student debt. >> now is not the time to make school more expensive for our young people. >> oh, yeah! ♪ >> the president with jimmy fallon today in north carolina. up next tonight, a woman who's in a class of her own. we'll meet your teacher of the year.

finally tonight, a woman who is being hailed as the best of the best in american classrooms. out of more than three million teachers in this country, she was honored today at the white house, as teacher of the year. we get her story tonight as a classroom leader in our education nation. here's nbc's kristen dahlgren. >> there's angel wilson. >> reporter: even outside the classroom, rebecca mieliwocki can teach us a lot. >> i think a great many americans wake up on a monday

morning sort of grumpy about what they have to do when they get to work. but i get up in the morning excited about what i get to do. >> reporter: at the white house today, that enthusiasm was honored at the highest level. >> and there is our 2012 national teacher of the year, rebecca mieliwocki from burbank, california. >> reporter: picked from 3.2 million american teachers, mieliwocki's students know why. >> what makes ms. mieliwocki a great teacher? >> she's amazing. she's the best teacher i've ever had. >> reporter: mieliwocki is humbled. >> i'm not the best teacher in america, there isn't one. >> reporter: she loves learning as much as teaching. >> i'm only as good as i am because i walked into other teacher's classrooms. >> reporter: she never loses her sense of humor. >> i have to say, she was a little goofy when i met her. >> reporter: for the 43-year-old, teaching was in her dna. the daughter of two teachers,

she tried law school and publishing, but finally, she realized this is where she belonged. here in her class, she tries to keep things fun for her students. she plays music, and the bell on her desk always rewards a right answer. >> the kids respond to her like cat nip with cats. they can't wait to get to class. >> reporter: at a time when the american education system is under fire and facing cut backs, she knows what's on the line. >> it's very important to me to get this right. the future of our nation depends on how strong our educators are. and i feel a strong obligation to be the best i can be. >> reporter: even on her day with the president, she was thinking about her students taking their state tests today. >> i am counting on you, you guys better bring it. you're ready. >> reporter: a long distance lesson in being the best. kristen dahlgren, nbc news, burbank, california. >> great story to end on as we complete our broadcast for this tuesday night. thank you for being here with us. i'm brian williams. we, of course, hope to see you right back here tomorrow

evening. good night. -- captions by vitac -- www.vitac.com ♪ nbc bay area news starts now. good evening, everyone, i'm janelle wang. >> i'm jessica aguirry. the ultimate in california's death penalty? california voters will decide whether the state should continue to execute prisoners. an initiative to end the death penalty will appear on the november ballot and if it passes more than 700 death row inmates would have their sentences changed to life imprisonment without parole. joe rose eto jr. shows us why continuing the death penalty would cut down on crime. >> reporter: when it comes to the issue of crime and