north of harming peace and stability. the north's new young leader, kim jong-un, has been threatening to attack the south and the u.s. on an almost daily basis. angered by tough new u.s.-led sanctions that followed the third nuclear test in the north. he's also denounced routine u.s./south korean military exercises which included two nuclear capable b-2 stealth bombers. south koreans have become used to the threats from across the border, but the shear volume and violence of the recent rhetoric has people on edge. i'm very afraid and scared, says this woman. though younger south koreans largely shrug it off, this one saying there is a slim chance war will break out. many in the south are now focused on the operations of a vast industrial zone, in calsong, just across the dmz, where 124 south korean companies directly employ more than 50,000 north korean workers. it's a big source of foreign

currency for the north. it's weathered many ups and downs in relations and is seen as a barometer of the north's intentions beyond the rhetoric. today the north threatened to shut it down, which would be seen here as an ominous development. in spite of all the rhetoric against the u.s., experts say that in the current tense atmosphere, the biggest danger is of a local skirmish or miscalculation which could then escalate. lester? >> ian williams tonight in seoul. as for this country, the white house said again today that it's taking the threats of north korea seriously. nbc's kristen welker is at the white house with more on that tonight. good evening, kristen. >> reporter: lester, good evening. white house officials are, of course, concerned, and they have the added challenge of reassuring south korea and other allies in the region that the united states will defend them if they are attacked. now, the white house described the latest pronouncement from north korea as an unconstructive statement, and tried to further downplay the situation by citing north korea's long history of

bellicose rhetoric. still, this is a tense moment. a chief concern, the leader of north korea is young and he's unpredictable. one senior administration official told me his father ruled from the shadows with occasional rhetorical flourishes, but the official said, kim jong-un has turned the hyperbole dial all the way up to 10. one foreign policy expert outside the white house said the problem is, his father knew where the line was, but it's not clear that kim jong-un does. the problem with all of this is that kim could lead to a miscalculation, which could ultimately provoke south korea to respond. white house officials watching this very closely tonight. lester? >> kristen welker at the white house. thanks. it's being called one of the worst public school cheating scandals in memory. for years teachers allegedly altered answers on standardized tests to improve results in atlanta. now dozens of educators have been indicted, including a former superintendent. nbc's gabe gutierrez has more tonight.

>> reporter: it's one of the largest cheating scandals ever in public education. former atlanta superintendent beverly hall and 34 other educators indicted friday on racketeering charges. investigators say they conspired to erase wrong answers on standardized tests, often for money. >> dr. hall had a contract that was set up to pay her bonuses when she achieved certain results. those results were caused by cheating. >> reporter: the district seemed to be performing well. earning hall half a million dollars in bonuses. she had been named national superintendent of the year in 2009, the same year, prosecutors say, widespread cheating took place. hall has repeatedly denied the allegations. first brought to light by reporters from the "atlanta journal-constitution" and state investigators who persuaded one whistleblower to wear a wire, and secretly record conversations.

investigators say some teachers would gather in locked rooms to change answers. but one of the accused, angela williamson of dobbs elementary, says that never happened at her school. she's stunned, since the school panel cleared her of wrongdoing last year. did you ever help your students cheat? >> i have a good heart. i always have. and i never, ever participated in any cheating. i did what was right for my students. and that is to teach them. >> reporter: at another school, christine collins, claimed her daughter fell behind, while her test scores seemed to improve. >> it's really hard. like i'm 15, and i'm reading on a 5th grade level. and it's not good. >> it's heartbreaking that we have individuals that would stoop that low in a situation for something as simple as money. >> reporter: cheating is not just a problem in georgia, as pressure to do well on standardized tests has grown.

in texas, a former el paso superintendent recently went to prison after removing students from classes to improve test scores. now the new superintendent in atlanta says the focus is on the students. >> we are moving forward, and we are executing for the good of the children of this city. >> reporter: moving forward, after an education scandal that prosecutors say was brought on not by children, but the adults entrusted to teach them. the grand jury was apparently so outraged at the former superintendent, that it recommended a bond of $7.5 million. if convicted, she faces up to 45 years in prison. >> gabe gutierrez from atlanta for us tonight. thanks. there is a health scare we're following tonight that involves thousands of people who may have been put at risk simply by going to the dentist. hundreds of them lined up in tulsa, oklahoma, today to be tested for hepatitis and hiv, after visiting an oral surgeon accused of unsanitary practices.

nbc's charles hadlock is in tulsa tonight with more for us. charles? >> reporter: good evening, lester. today was the first day that patients who may have been exposed to infectious diseases at a local dentist's office could come and get tested. 400 people showed up today, but there are thousands more who may have been infected. the line at the tulsa county health department stretched out the door today. hundreds of people who have one thing in common, all were patients of dr. scott harrington, whose dental practice is now at the center of a health scare. >> i figure i better get tested and be safe. it's the smartest thing to do. >> reporter: state health officials said harrington's clinic may have been the source of hepatitis in at least one patient, and fear there could be more. the health department has now notified 7,000 patients, who may have been exposed to hepatitis or hiv. >> we are here for the long run. we know that it's going to take a couple weeks, to months, to get everyone screened.

and so we are here and we'll have this clinic established here until we see the last person. >> reporter: in a 17-count complaint, the state board of dentistry accuses dr. harrington, seen here in an earlier photo, of being a menace to public health because of unsanitary practices found in his office. inspectors say harrington's clinic had rusty equipment, allowed dental assistants to perform i.v. sedation without a license and reuse needles and old drug vials. investigators say harrington's staff improperly sterilized tools with bleach, which caused them to corrode. harrington has surrendered his dental license and is cooperating with authorities. >> i just have been tested for hepatitis c. >> reporter: back at the long line at the testing clinic, linda harris awaits the results of her blood tests and fears for her loved ones if she's somehow infected. >> i'm really scared, because i feel like -- that's my fiance right there. if anything happens, you know, it's not good news, that he's

going to have to be tested. >> reporter: linda harris and all the others will have to wait at least two more weeks to know the results. lester? >> charles hadlock in tulsa. thanks. there's word tonight of a possible deal on immigration reform talks between the afl-cio and the chamber of commerce. the agreement revolves around a critical sticking point in how much to pay guest workers. details at this point are sketchy, but it appears both sides have agreed on a complicated system that won't drag down the wages of ordinary americans. a u.s. navy s.e.a.l. killed in a training accident this week has been identified. military officials say brett shatel was a highly decorated member of the famed s.e.a.l. team 6. he died when he and another navy s.e.a.l. collided in mid-air during a parachute training exercise over southern arizona. shatel was stationed in virginia. he leaves his wife and two young children. he was 31. in south africa, former president nelson mandela remains in the hospital tonight, but is said to be doing better as he

fights pneumonia. nbc's keir simmons now with the latest from johannesburg. >> reporter: nelson mandela is sitting up and talking, according to family members, after he was rushed from his home late wednesday due to a recurrence of pneumonia. doctors have now drained fluid from around his lungs. an official spokesman revealed >> doctors advised that he had developed an occlusion which has since been tapped and this has now resulted in his being able to breathe without difficulty. >> reporter: meanwhile, winnie mandela while at church for easter confirmed her former husband is doing well. >> we were very touched this morning when we heard. also wish him well. this is very inspiring. we have the lord on our side. this is a very difficult time. >> reporter: nelson mandela is

comfortable and responding to treatment, his doctors say. his grandson is expecting with confidence he will be home here soon, but said the family is taking time to cherish every moment with him. keir simmons, nbc news, johannesburg, south africa. when "nightly news" continues on this saturday, overcoming fears of having surgery. we'll show you how more and more patients are achieving that by getting a cutting-edge preview. later on this easter weekend, candy as an art form. a peek inside the world of peeps.

let's face it, no one looks forward to having surgery. for most patients, it's a leap into the unknown, something well beyond their control. but now with the help of mobile apps and cameras, some doctors are helping their patients get through it with less anxiety by giving them a preview of what they face. nbc's chief medical editor, dr. nancy snyderman, shows us how. >> reporter: "scarface," "the godfather," victor mechere is so used to playing the tough guy, not so tough after seeing his heart disease up close. >> you're showing me a picture of a heart. it was yellow and a lot of guck in there. >> reporter: dr. rob mischler knows every person who lands on his table would rather be anywhere but here. >> this is actually very cool. put the camera in there. >> reporter: so he came up with a tool to demystify surgery. the world-class surgeon films

his operations to make what he calls movie trailers for his patients, to put them at ease. what is it about the fear component of heart surgery? >> people understand that this is a life-and-death situation. without the surgery, they could die. and there is a risk with it. we're just going to go into my office -- >> reporter: marion needs a valve replaced in her heart. >> let's take a look here on the ipad. >> reporter: the images are graphic. >> here i'm placing a suture, right in the annulus. you can tell the difference. >> reporter: dr. mischler showing in minute detail how he will fix her heart. does this help alleviate any fears you had about what this surgery entails when you can look at it so graphically? >> yes. but i'm still worried about it, because you're getting operated on. >> but that's a sign of an intelligent patient. >> reporter: remember the old board game operation? touch surgery, an app doctors

can use with their patients. psychologist robin goodman hopes pocket technology can help the estimated 10 million americans who are so afraid of doctors, that they never seek medical advice. >> they're dealing with a reality rather than their fears and fantasy. >> you actually saved my life, i guess, because i was a goner. >> the pictures, they scared you, but they helped you understand what the problem was, right? >> they convinced me. >> reporter: high-tech tools that strengthen the bedside bond between doctor and patient. >> so what do we do in italy? >> we start the ball. >> reporter: dr. nancy snyderman, nbc news, new york. when we come back, a battle for survival playing out in the pacific.

if you came of age in the last 50 years, there is a better than even chance you have heard his work. legendary record producer phil ramone has died. he produced some of the biggest names in the business from barbra streisand, to bob dylan, paul simon and billy joel. ♪ i want you just the way you are ♪ >> in 1979 "just the way you are" earned ramone and billy joel a grammy for record of the year. ramone won 33 nominations. he produced duet albums for frank sinatra, and later tony bennett. one of his grammys was for the

soundtrack to the 1980s film "flashdance." phil ramone died this morning from complications related to an aortic aneurysm. he was 72. scientists in southern california are increasingly concerned about the large numbers of starving sea lion pups washing up on the beaches. more than 900 of the animals have been rescued since january, leaving scientists scrambling to figure out why. we get a report tonight from kristen dahlgren. >> reporter: in southern california, a massive rescue effort to save hundreds of starving sea lion pups stranded along the coast. >> they're hypothermic, they're hungry. they're basically starving pups, just so cold without the body fat. >> reporter: rescue centers are overflowing with pups coming in so malnourished, they have to be tube-fed. and beyond the sad eyes are alarming statistics. last year through march, there were 88 strandings in southern california. so far this year, there have

been 948. and the numbers are rising. southern california centers can't keep up. this week they had to ship some animals all the way to northern california, to the marine mammal center in sausalito. at nine months of age, they should weigh between 60 and 70 pounds. these guys are coming in weighing as little as 18. it's estimated only half the pups born last june even made it this far. scientists are trying to figure out why. their best guess is the sea lions' food source, sardines and anchovies, isn't there this year, forcing moms to go further in their search for food, leaving pups unable to nurse, and looking for comfort wherever they can. >> if you're a young california sea lion, inexperienced being out on your own, you're weak, you're going to find anywhere that seems safe, and anywhere that you have the energy to get to. >> reporter: in the hospital, they're given the nutrition they need with the hopes they'll eventually be released back into the wild.

but on the beaches, it is still a struggle, a fight against starvation, and a race to rescue all they can. kristen dahlgren, nbc news, sausalito, california. we have an update on the polar bear cub we told you about last week. some new images of kali being raised by zookeepers in anchorage. since he arrived a few weeks ago, kali gained about a pound per day and now weighs 31 pounds, almost as much as this easter egg. kali's next stop is a zoo in buffalo, where he will join another orphaned bear named luna. up next, the sweet taste of success. 60 years after peeps first came out.

tomorrow is easter sunday, and for many, it's hard to imagine spending that holiday without a certain small colorful marshmallow snack. peeps turned 60 years old this year and the story of the sugary treat has been one of sweet success. nbc's katy tur has our report. >> reporter: every winter, spring starts to line the shelves. hot pink, neon yellow and electric blue faces that can trigger a thousand memories of easters past. >> i love how they're yummy and sweet and gooey. >> they're just delicious. >> reporter: 60 years since the first peep was hatched. the sugar-coated marshmallow has become a lot more than just a treat. they can be a test of fortitude. a test of true love.

or for the kids at friendship valley elementary in maryland, a test of the mind. >> we had to work on how we were going to engineer and design the peeps contraption. >> reporter: in the world of peeps, there are no rules, especially when it comes to eating them. bite the head off first. after all, some say that is the most humane way to do it. nibble all around the sides, but that's just cruel to those waiting in the wings. or stick the whole thing in your mouth at once and let it dissolve so the others don't know what happened. although if you ask anyone who works at the peeps factory, the best way is any way, so long as it's right off the conveyor belt. how many do you eat in a day? >> i have to be honest with you, no more than a dozen. >> reporter: aptly situated in bethlehem, pennsylvania, the peeps factory turns out 4 million chicks and bunnies a day, 1 billion for easter alone.

3,810 of those went into big bird at this year's peep art show in carroll county, maryland, where their peep art could even be a peep bart. and where the friendship valley kids hope their masterpiece will take home the gold. >> actually, ours is with it. >> reporter: a place and a treat that can even make a grown-up feel like a kid again. i went to the peep factory. >> aw! >> reporter: nah, nah, nah, nah, nah, nah. katy tur, nbc news, westminster, maryland. that's "nbc nightly news" for this saturday. i'm lester holt reporting from new york. for all of us here at nbc news, good night.

>> announcer: nbc bay area news starts now. right now at 6:00, a trip home for spring break college student ends in death. he was gunned down in the bay area. tonight, what investigators say led up to the shooting. also -- >> it's really important that the guys from the area give the ultimate sacrifice in vietnam. >> it's called the sons of san jose. a new memorial that drew a crowd today. spring showers could affect your plans for easter sunday. >> good evening. i'm terry dwyer.

police are looking for a person who shot and killed a 19-year-old student. it happened on 24th and bryant street. kimberly terry is there with more for us tonight. kimberly? >> reporter: diane, that young man was shot right in front of his home and his family tells us tonight that it was his father who heard the gunfire and went downstairs to find his son. he was taken to the hospital where he later died. his family has identified him as jacob valdavieto. he was walking to his parents' house last night about 3:00 a.m. overnight that is when a car pulled up, a latino man got out, asked if he was part of a gang and shot him. the suspect is still on the loose. according to his family and police, he has no gang ties. his loved ones say he was a good guy and has a lot of family and is loved by everyone. he was dedicated to sports, particularly football. he graduated from archbishop

rear done high school. he was going to college in portland and he was playing football. he was scheduled to go back to school on monday. they are still looking for the suspect in this case. if you know anything about the deadly shooting you are asked to call san francisco police. live in san francisco, kimberly terry, nbc, bay area news. >> kimberly, thank you for the update. we have new information on a kidnapping case out of southern california. police identified a suspect today, 30-year-old tobias dustin summers is wanted for kidnapping a girl last week. she was abandoned hours later in front of a hospital. summers was recently released from prison and apparently has a lengthy criminal record. police are asking anyone for information on his whereabouts to call the los angeles police department. two people are recovering tonight after their car plunged into a water way in