♪ tonight on "nightline," breaking news. the official word, no survivors from flight 370. the question is why? malaysia airlines facing questions about why their plane changed its flight path so drastically, vanishing in the indian ocean thousands of miles from its destination. i'm scared of you. a fashion model and reality star -- >> hey, guys, i'm reeva. >> killed on valentine's day by her beloved boyfriend, one of the fastest men on earth. today in court their troubled relationship in the spotlight. >> i'm scared of you sometimes. >> final text messages reveal her secret fear. working out for just 20 seconds to get healthier, look better, live longer.

sound impossible? >> one, two -- >> this doctor swears that less is more. could it work for you?

from new york city, this is "nightline" with juju chang. >> good evening and thanks for joining us. malaysia airlines tonight is addressing the public for the first time since officially announcing there are no 75ers from flight 370. they alerted some distraught family members of the devastating news by text message. the airlines chairman told reporters it's a sad day for the airlines and the families. now one mystery may be solved. but so many questions remain. why did a plane seemingly in perfect condition fall from the sky? abc's bob woodruff is in the midst of it all and is reporting from kuala lumpur. >> reporter: juju, i have to say

i was absolutely shocked there was very little information in this presser. the airline officials gave their prayers and condolences to the families but they could not give detail of what they found, in terms of debris, if it is part of the plane, why they think for sure the passengers did not survive. there's anger, especially in beijing. part of it is the families did get the word their loved ones had died by text message sent to their cell phones. malaysia airlines ceo defended it today saying they did it because it was the only way to inform the family quickly enough before it goes public. he said they had a limited amount of time. now the families could be flown down to perth by the airline if they want just in case the plane is found and that search for the bodies begins. juju? >> thanks to bob woodruff for the latest reporting from kuala lumpur. and the prime minister of australia has just announced that they are waiving visa fees for those families who are going down to australia. just minutes ago the australian

defense minister said they have not successfully identified or recovered any debris from flight 370. time is running out in the desperate search for answers with only 13 days to go before the plane's black box stops pinging. its crucial data could be lost forever. abc's david wright is in astronaut along with investigators as they hunt for clues. >> reporter: we now know what happened to flight 370. but why? that more profound question is still a mystery. the answer lies about two miles down on the ocean floor. for the families of 239 people who were hoping against hope, heartbreak tonight. there are no survivors, and there are still plenty of unanswered questions. the satellite firm immarsat provided clues to the few answers we have. the firm helped narrow the final flight path based on pings it collected from the plane as it flew. >> the pings match our plot for

the southern route. they do not match the northern route. and therefore, the northern route is ruled out. >> reporter: but where exactly did it go down? that's still only a guess, based on how much fuel it had left. today an australian p-3 orion finally spotted new clues. a gray or green circular object and an orange rectangular object floating in the indian ocean. we don't yet know if they were from the plane. the flight crew put down a marker and called in a supply ship, the only vessel nearby, the hmas "success." the "success" still hasn't succeeded in retrieving them. the weather too rough. today the entire search was called off because of bad weather. but for a week now the search planes have scoured these waters, poring over a remote stretch of sea bigger than the state of california. >> our mission today is to go out to our search area. we're conducting a visual search, looking for any objects in the water. >> reporter: we've been with them, chasing grainy satellite images from the u.s., china, and france.

>> any word if anybody's seen anything? >> nothing yet. >> reporter: the radar array starts pinging. >> i just got two additional hits on the northern side of our search area. >> reporter: multiple content. each of them some sort of anomaly on the water. >> the board is lighting up, huh? >> getting indications on our screen. >> reporter: but in these conditions, forget about it. the crew circles three times over the radar contact with no success. as tough as this first stage has been, stage two will be even tougher because the heavy wreckage is miles away and miles down on the ocean floor. >> the computer models that we have done shows that the debris has moved almost 500 kilometers away from where it originated from. >> because it's been so long? >> it's been so long and the currents are quite strong. >> reporter: oceanographer chadarachi padiarachi has made a map of where he thinks the debris likely came from, based

on the ocean currents. finding it will require sophisticated submersible robots like these. >> so it's like a drone that goes underwater. >> exactly. >> reporter: his drones aren't capable of going deep enough, but the u.s. navy's are. remember, we're talking about water that's deeper than where "titanic" sank. >> the average depth is 4,000 meters which is about 12,000 to 13,000 feet. the maximum depth is 10,000 meters. >> 30,000 feet under the sea. >> if you put everest there you won't see the top. >> reporter: they'll be listening for pings from the so-called black box. the flight data and cockpit voice recorders. it is now truly a race against time. the batteries on those black box recorders running out. and those devices are our best hope for finding answers on what happened in the final hours of flight 370. juju? >> thanks, david. of course we'll stay on this story and bring you critical updates as soon as we learn more. for now we go to the other

side of the world, where a south african superstar is on trial for alleged murder. today in court paralympian oscar pistorius heard words from beyond the grave. text messages from the girlfriend he shot and killed. abc's matt gutman is in pretoria with the latest. >> reporter: oscar and reeva seemed to sizzle on the red carpet. they were south africa's it couple. >> an historic event. >> reporter: the double amputee who shined on the olympic stage. >> the kind of event that makes us love the olympic games. >> reporter: and the lawyer turned model. >> hey, guys. i'm reeva. >> reporter: on the verge of stardom. but theirs was a relationship that may have burned too hot. at oscar pistorius's murder trial monday, a voice from beyond the grave. forensics experts cracked open reeva steenkamp's cell phone exposing the inner workings of what the prosecution portrayed as a troubled relationship. >> i'm scared of you sometimes and how you snap at me and how you will act to me.

>> reporter: intimate text messages the couple shared in the weeks before oscar pistorius shot and killed her in his bathroom last valentine's day. >> i get snapped at and told my accent and voices are annoying. i touch your neck to show you i care. you tell me to stop. stop chewing gum. do this, don't do that. >> reporter: pistorius claims he mistook her for an intruder. but the prosecution building a case that this was not mistaken identity, but murder. possibly triggered by a violent argument. the key clues to which may reside in steenkamp's cell phone. the expert said most of their hundreds of messages were normal exchanges between a couple, but in some read in court pistorius sounded jealous and quick to anger. >> i was upset that you left -- that you just left me after we got food to go talk to a guy, and i was standing tight behind you watching you touch his arm and ignore me.

>> reporter: her feelings hurt, writing back -- >> i regard myself as a lady, and i didn't feel like one tonight. after the way you treated me. i can't be attacked by outsiders for dating you and be attacked by you, the one person i deserve protection from. >> reporter: reeva's friends portrayed her as sunny and supportive. >> she was just always happy and smiling. and always had the most amazing outlook on life. >> reporter: but they also told abc news that reeva had been in a bad relationship in the past. she knew the signs. >> she'd been in an abusive relationship. >> reporter: the greatest irony. >> she was going to give a talk to schoolgirls at a high school that day, actually, about abuse. >> reporter: but pistorius, the seemingly invincible athlete, was also vulnerable. especially in his youth, when he wrote he was bullied at school. his mother would die tragically shortly after that.

then oscar's greatest triumphs came in a tumble. olympic victory in athens, beijing, and london. in his adulthood pistorius would take steps to protect himself from threats that went beyond bullying, surrounding himself with new friends and new weapons. >> i heard he had guns. >> reporter: fame and success that seemed to change him. >> what would you do if you had heard that your client had been driving in a car at 260 kilometers an hour, 180 miles an hour? >> those are things that really shocked me when i heard. >> how much of that do you think is media hype and how much of it do you think is oscar pistorius changing? >> you know, i think it's oscar pistorius changing. i mean, they were going 260. he was shooting the gun out the sunroof. i mean, he did do those things. >> reporter: ebba gudni never saw that imperious, jealous side of pistorius. >> he's got a big warm heart. >> reporter: her son like pistorius was also born without fibulas. they met in her native iceland. >> he takes care of people.

he's funny. he's positive. he's very brave. and he always tries to make sure that everybody's okay. >> reporter: and early today the most harrowing testimony yet. >> the thing that i remember the most, and i don't think i'll ever forget, was the screaming. >> reporter: in a trial so much about sound, we could only hear the testimony of oscar pistorius' neighbor, annette stip. >> i could still hear the screaming up until the first or the second set of shots. >> reporter: she said she heard a woman's screams after an estimated ten minutes of commotion. she then heard shots and then silence. there were no eyewitnesses that night. only so-called earwitnesses. the fragments of information as fleeting as those text messages. >> i'm scared of you sometimes. >> reporter: but today these fragments, according to the prosecution, painting a very different tale than the one told by oscar pistorius of a peaceful evening at home and a case of mistaken identity. in south africa the prosecution needs only to convince one person.

there is no jury, just the judge. and only one man who knows the truth. and oscar pistorius could testify as early as this week. for "nightline" i'm matt gutman in pretoria, south africa. >> our thanks to matt gutman from a dramatic day in court. next up for us, hate to work out? what if you only had to for a few seconds? say, 20 seconds. when jake and i first set out on we ate anything. but in time you realize the better you eat, the better you feel. these days we both eat smarter. and i give jake purina cat chow naturals. made with real chicken and salmon, it's high in protein like a cat's natural diet. and no added artificial flavors. we've come a long way. and whatever's ahead,

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in an age of instant gratification where we want everything fast, from fast food to fast fashion, we expect the same from our workouts. there was the seven-minute workout. then the four-minute workout. but what if you could burn fat and be healthier even faster? enter the 20-second workout. ♪ it may not the most dignified workout. >> it is burning.

>> burning in the groin. >> reporter: but michael mosley, a doctor turned best-selling author, says that just 20 seconds of grunting, groaning, and pushing your way through the pain, even in business attire -- >> oh, my god. >> you can do it. >> i can't -- that's 10 seconds. halfway there. >> whoo. five, four, three, two, one. >> reporter: will make you not only skinnier but healthier. we're talking about high-intensity interval training. pushing through to the absolute limit. mosley calls it fast exercise. and it's the title of his new book. but can one minute total three times a week really lead to remarkable medical changes? the good doctor suggests it's an aerobic fountain of youth, a shortcut to getting maximum benefits with minimum work. >> what's the key to high intensity? >> this regime, doing short bursts of intense, seems to be much more effective not only for

losing weight but also for improving your insulin sensitivity. >> reporter: mosley's controversial take points to a growing body of science which suggests it's the stress and intensity of exercise, not the duration, that's beneficial. we're talking weight loss, reduced cancer risk, and something that hits close to home for michael, diabetes. >> two years ago i discovered i was diabetic. i was a bit overweight. that got me into fast diet but also got me into a fast exercise regime. and now i'm 20 pounds lighter and my blood sugars are completely normal. i've gone from diabetic to normal. >> reporter: as a guinea pig for his own research, he stays healthy now. but not with a fancy gym. >> running is a fabulous form of exercise. you can do it in any building which has three floors -- >> why am i getting nervous? >> i'll give you a head start. ready, steady, go. >> we're really running? >> it's another 20-second workout, one you can do right in your own stairwell, in a suit, whether you're fit or fat.

>> how was your workout? >> that's it? that was intense. also vaguely humiliating because you were so much faster than me. >> come back in two weeks' time and i'll bet you beat me. >> really you no longer have an excuse you don't have time to work out. >> not at all. >> reporter: the fast workout is just the latest lifestyle trend from dr. moseley. his bbc documentary which aired on pbs "east fast and live longer" launched an international best-seller about the benefits of a two day a week fast diet. it all began with a wake-up call for the good doctor about where his then 53-year-old body was heading. he'd already lost his father to diabetes. >> i discovered that my fasting glucose levels were those of a diabetic. my doctor said, you need to start on medication. >> reporter: researchers across the united states have been finding astonishing results from severe calorie restriction. decreased cancer risk, increased life expectancy, even improved brain function. so mosley came up with a diet where you fast on two random days of the week, say, monday

and thursday, and eat whatever you want the remaining five. >> just to be clear, you're not telling people to starve themselves. >> oh, absolutely not. in the regime that i'm suggesting, the maximum you ever go without food is 12 hours. >> reporter: mosley believes he can apply the same principles from his diets to his workouts by looking carefully at the science to trick your body into being healthier. >> when i did the fast diet, the fasting, again, the benefits there come from stressing your body. it's a hunger thing. >> right. >> and the same is true of exercise. >> reporter: high intensity interval training, or h.i.t., is nothing new in the exercise world. it's the cornerstone of boot camp drills. the wildly popular cross-fit phase. daniel rohana incorporates high intensity routines for his clients at reebok. >> efficient and effective. that's the biggest thing most people get from it. >> reporter: but rohana says high intensity should be balanced with other types of exercise. >> i do think high intensity's got its place, but i think, you know, a well-rounded program with much more scientific

background is much more efficient. >> reporter: but there are critics who say just a few minutes a week really won't cut it. >> exercise should be varied and gradual. so high-intensity training should be a supplement to that. >> reporter: and working out with this much intensity isn't easy for everyone. >> if you're a couch potato and you think oh, 20 seconds and i'm done -- >> if you don't exercise, don't try it. if i ran a sports medicine clinic, i might want you to if i need some new clients. >> reporter: when it comes to working out, the idea that less is more can be very tantalizing. >> go, go, go! >> are we done yet? >> the "fast exercise" book will be in stores and online tomorrow. coming up next for us, ever wonder what it looks like to b.a.s.e. jump off the freedom tower? sion. ometimes, i still struggled to get going,

even get through the day. so i was honest with my doctor. i told him i'd been feeling stuck for a long time. he said that for some people, an antidepressant alone only helps so much and suggested we add abilify (aripiprazole). he said that by taking both, some people had symptom improvement as early as 1 to 2 weeks. i wish i'd talked to my doctor sooner. [ female announcer ] abilify is not for everyone. call your doctor if your depression worsens or you have unusual changes in behavior, or thoughts of suicide. antidepressants can increase these in children, teens and young adults. elderly dementia patients taking abilify have an increased risk of death or stroke. call your doctor if you have high fever, stiff muscles and confusion to address a possible life-threatening condition. or if you have uncontrollable muscle movements, as these could become permanent. high blood sugar has been reported with abilify and medicines like it and in extreme cases can lead to coma or death. other risks include increased cholesterol, weight gain, decreases in white blood cells, which can be serious, dizziness on standing, seizures, trouble swallowing and impaired judgment or motor skills. [ terri ] since adding abilify, i feel better.

abilify and my antidepressant make a pretty good team. [ female announcer ] ask your doctor about a free trial of abilify and go to addabilify.com. [ female announcer ] ask your doctor about a free trial of abilify to manage your money.r guy around 2 percent that's not much, you think except it's 2 percent every year. go to e*trade and find out how much our advice and guidance costs. spoiler alert. it's low. it's guidance on your terms not ours. e*trade. less for us, more for you.

at kaiser permanente we've reduced serious heart attacks by 62%, which makes days with grandpa jack 100% more possible. join us at kp.org and thrive. and now you're about to witness an illegal act. breathtaking to be sure. it's new video of three b.a.s.e. jumpers who leapt off the freedom tower. there they go.

the daredevils released video of their stunt on youtube and are set to be arraigned in court after turning themselves in. they leapt off the 1,776-foot-tall tower. captured by a helmet cam. literally a birdseye view. there goes the parachute. over lower manhattan. after freefalling you see the jumper float down to a safe landing. and of course their day in court is ahead. thanks for watching abc news. tune in to "gma" in the morning. and as always, we are online at abcnews.com. good night, america.