on the broadcast tonight, behind the mask. the brutal isis killer with the knife beheading hostages including three americans. tonight, jihadi john has been identified. what secret intelligence has known about him for years. also, the priceless destruction underway by isis, wiping out some of the most important pieces of history. nbc news exclusive, robin williams' daughter zelda breaking her silence about the sudden loss of her father and the legacy she carries on. and a whodunit. a shocking heist after the oscars. tonight a big star at th of a mystery. "nightly news" begins now. from nbc news world headquarters in new york, this

is "nbc nightly news," reporting tonight lester holt. good evening. the identity of the british-accented executioner, the man who's become the face of isis brutality has apparently been unmasked. until now known as jihadi john, but senior u.s. intelligence official confirms that a london-raised former university student is the sinister figure whose videotape taunts and beheadings of western hostages have horrified people around the world. and tonight with the real name we are beginning to unravel his journey from the neighborhoods of west london to syria to the hierarchy of isis. with more, here's nbc's keir simmons. >> we are an islamic -- >> reporter: his british accent was one of the few clues to his identity in isis propaganda s eyes showing from behind a hood. but today he was identified. he is mohammed emwazi, came to

uk in 1994. the son of a well-to-do family that reportedly lives middle class home wher gathered far from the desert where emwazi was the front man. american journalist james foley, then journalist stephen sotloff, british aid workers, american aid worker peter kassig. this man knew emwazi in london.sound like the man you knew? >> a little bit. i really don't want to be certain, but i can't deny the fact that i do find there were a number of similarities for sure. >> reporter: the identified emwazi says he wasn't always violent. >> he was a shy person. >> -- he was very interested devoted to religion, devoted to his family. >> reporter: he stud

programming at wes university. leaving in 2009. emwazi did have connections to extremists in somalia and was known to the british security agencies. but he left britain in 2012 for syria where he joined isis and became a symbol of their brutality. today the daughter of one slain hostage said identifying emwazi was a good step, but she wants more. >> it's a good step, but i think all the families will feel closure and relief once there's a bullet between his eyes. >> reporter: and tonight there are questions about how mohammed emwazi was able to leave the uk and join isis despite being on the security agency's radar. and questions about what happened to this british-raised and educated young man that apparently turned him into a world famous and cold-blooded killer. lester. >> keir simmons in l tonight. thank you. the dangerous reach of isis extends all around the world including into this country using the power of social media. the arrest of three men from new york and what the fbi says was a plot to support isis seems to be the latest example of a rapidly growing trend.

and a top fbi official admitted today that we are "losing the battle to stop the spread online." our justice correspondent pete williams is monitoring the latest from our washington newsroom. pete, good evening. >> reporter: lester, good evening. the latest is federal authorities are questioning a man in norfolk, virginia to see if he played a role in raising money for the plan to travel to syria. no charges yet officials say as they continue their investigation. in the brooklyn neighborhood where the men charged with supporting isis lived and worked, a community leader says he'd tried to talk one of them habivoev out of becoming radicalized. >> we had an argument with the gentleman about understanding of the way he understands islam. >> reporter: u.s. officials say the brooklyn men were lured by isis propaganda and that two of them bought plane tickets to get to syria. intelligence agencies say as many as 20,000 people from 90 countries have traveled to syria

to fight, many to join isis. they say 180 americans have either gone or tried to. 20 from the u.s. have been stopped in the past year and a half ranging in age from 15 to 63. isis now has social media feeds in 23 languages. and the director of national intelligence said today it's virtually impossible to stop. >> the problem there is their ubiquitous use of the media, and so the challenge is how do you take down the internet? >> reporter: france's interior minister in california last week urged google, facebook and twitter to be more aggressive in weeding out isis propaganda instead of relying on users to flag it, a process youtube says works quickly. some in congress say social media should have zero tolerance for jihadist propaganda. >> we would never allow isis to take out an ad in "the washington post" recruiting folks to go to syria, radicalize and come back and kill us. we wouldn't allow that to occur. >> reporter: in minnesota today a teenager stopped last may at

the airport admitted in court he was trying to get to syria. he pleaded guilty to a terrorism charge and could face up to 15 years in prison, lester. >> all right, pete. isis has demonstrated time and time again its lack of respect for human life. it comes as little surprise that it has no respect for human history either. we're now seeing shocking images of isis members laying waste to priceless artifacts in the very cradle of our civilization. our chief foreign correspondent richard engel has our report. >> reporter: add cultural genocide to isis' growing list of crimes. the group which has killed, terrorized and uprooted hundreds of thousands of people in iraq and syria is now destroying their heritage too. [ speaking in a foreign language ] we were ordered by our prophet to take down old idols and destroy them, says this member in a video released by the group. which includes music and slow motion sequences. then the men go to work

ransacking mosul's renowned museum and a nearby archaeological site, demolishing irreplaceable statues and works of art. some crumble with a mere push. others require more effort. the big ones are defaced with power drills. including this winged bull, a god who protected the syrian empire 2,500 years ago, now powerless against these modern day vandals. >> to see these pieces being smashed like that is really heartbreaking. >> reporter: archaeologist michael donte has worked and studied the region for 20 years. >> isis is conducting a war on culture, war on cultural diversity. >> reporter: isis is taking a hammer to history systemically wiping out traces of prehistoric culture in areas under its control. destroying artifacts of civilization itself. richard engel, nbc news, istanbul. back in this country now, the winter without mercy brought

much of the south to a grinding halt over the last 24 hours. paralyze of snow and ice. while in the midwest and the northeast bitter cold is returning to areas that have this season. nbc's peter alexander has more on the freeze that feels like it's never going to end. >> reporter: offshore and on ice, dozens of lobster boats frozen in place in maine for weeks now. fishermen unable to do their jobs. in connecticut temperatures diving into the teens, water freezing as it left the hose at this house fire. and in new hampshire a harrowing survival story for dean mullens buried alive for hours after snow slid off his roof right on top of him. >> i had no time to move. it was just moving so quickly. and ended up pinning me on my back. >> reporter: from the midwest to the deep south, punishing cold and snow. >> i'm kind of sick of it, yeah. >> reporter: more than a foot in alabama stranding hundreds of drivers on i-65 overnight. >> take what the road gives you, you know?

and deal with it. and be calm and go slow. and you'll make it through. >> reporter: more than 11 feet in maine, 132.5 inches, tens of thousands still without power in north carolina. and how about that cold? cleveland on pace for its most frigid february on record. both syracuse and bangor en route to their coldest month ever. >> nonstop. >> nonstop. day and night. >> reporter: in virginia we met a plumber whose business is showing no signs of cooling off. >> been a nasty winter. >> reporter: still, this winter is producing stunning scenes like nantucket's nearly frozen waves, this bald eagle keeping her little ones warm, and along lake superior so cold it's now safe for wisconsin's famed ice caves to welcome guests again. spring barely three weeks away. peter alexander, nbc news, arlington, virginia. >> and don't look now, just about three weeks to spring and there is another big snowmaker on the way for much of the country. janice huff is in the weather center.

janice, notice i no longer ask you if there's relief in sight. i know the answer. >> you know what, lester, some parts of the northeast that have been dealing with this brutal cold for so long will get a bit of reprieve next week for a brief time. but overall we're still stuck in the pattern. and now a snowstorm that will be developing over the southern rockies is going to move out into the plains over the next couple of days. so for tonight around denver south towards albuquerque in the higher elevations up to a foot of snow expected. that spreads towards dallas on friday afternoon with some light snow, looking like maybe one to three inches towards oklahoma city. and then another snowstorm, another piece of energy forms another snow area on saturday afternoon. that's wichita, oklahoma city, that spreads towards st. louis by sunday morning and then towards chicago later in the day on sunday and the afternoon. south of that towards cincinnati a mix of rain, maybe some sleet in the warmer air. temperatures across much of the northern tier are still in the single digits. windchills are still below zero in many spots. and we're still going to see waves of that cold coming

through over the next several days, lester. >> janice huff, thanks very much. now you've heard all this talk about the future of the internet. it may have just been decided in a landmark vote today by the fcc. it concerns net neutrality, which supporters say will ensure open access to the web for everyone. opponents however say it amounts to government control over the internet. nbc's tom costello explains what it all means for you. >> reporter: to understand what net neutrality means, think of the internet as a super congested highway with most of the wider lanes taken by big fat trucks carrying content like amazon, netflix and hulu. the fcc's new rule means those big companies would not be able to pay to dominate the fast lanes. all of us from students at home to mom and pop businesses to the amazons of the world will be guaranteed equal access to the fastest service. >> the internet is simply too important to allow broadband providers to be the ones making the rules.

>> reporter: the new fcc rules will also prohibit internet service providers like verizon, at&t and comcast, nbc's parent company, from slowing down internet traffic and blocking access to competitors. that means a vast majority of us will see no change to our internet service. and internet providers will not be allowed to limit what we see at home or on our smartphone. >> this is about preventing a future where some websites would have gotten preferential treatment over other websites. >> reporter: critics say the new rules amount to government overreach. >> this is not what the internet needs. and it's not what the american people want. >> reporter: expected now, a vigorous legal challenge to this new law of the web. tom costello, nbc news, washington. we turn now to a hollywood mystery after the oscars, a heist involving one of the biggest stars on the red carpet. academy award winner lupita nyong'o, she's missing something that's very expensive that tens of millions of people saw days ago stolen right from under her nose. nbc's hallie jackson reports on the race to find it.

>> reporter: it's a hollywood whodunit. a jaw-dropping dress that dropped off the radar. just three days after actress lupita nyong'o wowed at the oscars winning raves on the red carpet. nyong'o says it took a village to get her into the gown, weeks to create it, but it disappeared in a matter of minutes from a high-end hotel in west hollywood where the actress had been staying. the custom calvin klein created from 6,000 rare pearls worth an estimated $150,000. >> i have never, ever heard of an oscar gown being stolen. >> reporter: this dress has become so famous. what can you do with it once it's stolen? >> it's true. they can dismantle the dress, restring the pearls and nobody would know those pearls came from that dress. >> reporter: l.a hope surveillance video from the hotel, which says it's working with police, tips them off to whoever took the dress.

nyong'o's not commenting and neither is francisco costa, one of the designer who helped elevate the look. for a fashion icon it's now a stunning wardrobe malfunction no one saw coming. hallie jackson, nbc news, los angeles. a lot more news ahead tonight including our nbc news exclusive, breaking her silence about the tragic loss of her father. robin williams daughter speaks for the first time about the questions surrounding his death. also, the slow-speed chase in the wild west that captivated folks all across the country today. the ending, you just got to see for yourself. the ending, you just got to see for yo (woman) the constipation and belly pain feel tight like a vise. how can i ease this pain? (man) when i can't go, it's like rocks piling up. i wish i could find some relief. (announcer) ask your doctor about linzess-- a once-daily capsule for adults with ibs with constipation or chronic idiopathic constipation. linzess is thought to help calm pain-sensing nerves

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in the six months since his death robin williams family hasn't said much publicly, preferring to mourn in private. but now his 25-year-old daughter zelda is breaking her silence in an exclusive interview with our national correspondent kate snow about her father's legacy and how she copes with questions surrounding her sudden loss. >> gets a lot of attention. >> reporter: after her father's death zelda williams tattooed a hummingbird on her right hand because she wanted to see it every day. >> i like hummingbirds. humming birds are fun and flighty and strange. it's hard to keep them in one place. and dad was a bit like that. keeping a conversation in one moment was impossible with him. >> look at the car! look at the car! >> for me it was a reminder i wanted. >> reporter: i lost somebody to suicide too, so i know that there's often that sort of, why

did this happen question. >> i don't think there's a point. >> reporter: you'll never know. >> no, it's not important to ask because it's -- >> reporter: that seems to me what all the people who knew your dad as a fan and loved him, when it happened everybody wanted to know why, how could this happen. >> diseases are until we find out exactly how they work, we don't have an explanation. a lot of people who have been through it and lost someone in any way, the ones that i found that have gone to lead very full lives found that they just had to know that there's no point questioning it. and there's no point blaming anyone else for it. there's no point blaming yourself or the world or whatever the case may be.

because it happened, so you have to continue to move. and you have to continue to live and manage. >> reporter: on friday in los angeles zelda williams will present a noble award to a group that robin williams worked with for years that provides prosthetics to athletes with disabilities. >> he's done charity as long as he had the ability to do it. that was what his favorite thing other than comedy really was. >> reporter: she wants to carr on her father's charity work because it was so important to him. she knows she's not the only one who misses her father. and everyone has a favorite memory. >> the world, as i said, keeps spinning. doesn't mean he was never on it. >> reporter: kate snow, nbc news, los angeles. and we've got more to tell you about as we continue tonight. we'll be back with a story that had a lot of o talking. also, excitement building tonight after a mysterious announcement by apple. announcement by apple. apples fall, but the apples of your cheeks don't have to. defy gravity. juvéderm voluma® is the only fda-approved injectable gel

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will hold an event on march 9th with a message that reads simply spring forward. it comes amid speculation that the launch of a highly anticipated apple watch is near. the company has previously said the watch would ship in april. a major moment for g giffords, the former arizona congresswoman who survived a shooting attempt on her life. a navy combat ship named in her honor hit the water for the very first time this week in alabama. it won't officially launch until later this year. in the meantime the u.s.s. gabrielle giffords will get some finishing touches. and about last night, we had an overwhelming response to our "making a difference" story. we brought you about the prospector movie theater in ridgefield, connecticut, and its mission to give people with disabilities what they say they want most, jobs and meaningful employment. the staff watched from the theater and sent us this photo. they've heard from people across the country, some who want to bring the idea to their own communities. if you missed the report, it's on our facebook page at nbcnews.com.

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for annuities, insurance and it was a desperate chase today for two fugitives and it gripped the nation as it played out live on the tv. in the spirit of butch and sun dance, or maybe thelma and louise, they made a break for it together in the phoenix suburbs. these were no ordinary o and reigning them in was no easy task. nbc's miguel almaguer has the wild tale. >> reporter: in sun city today this may have been the very definition of the wild west, a slow, sometimes high speed pursuit of two lamas on the loose breaking away from their owners, at times from each other, seizing their moment and their shot at freedom. >> something you don't see every day. >> we'll keep an eye on this, folks. >> reporter: the two-hour chase carried live on local, even cable news. this wild tale dubbed lamas on the lam. the lama drama trending on

twitter. the arizona cardinals ag one-year deals w loose. the lama chase, the biggest since o.j. it's gotten wild out west before. we've seen bears in backyards running from the law. >> there goes momma climbing to get her baby. >> reporter: ducks have made a dash, or at least a slow waddle along the freeway. and a moose on the loose brought traffic to a standstill. but this was lamas. lamas. >> at one point one of the deputies was trying to capture a lama with crime scene tape. >> reporter: like most getaways it didn't end well for the suspects, running out of breath and time, they were lassoed by modern day cowboys. a good run while it lasted. miguel almaguer, nbc news, los angeles. that will do it for us on this thursday night. i'm lester holt. for all of us at nbc news, thank you for watching and good night.

lights, camera, access. ♪ >> what caused madonna's fall and a lot more went down at the brit awards. i'm billy bush. what did kanye do to cause these