p this is "nightline." p>> tonight, how social media pturned into a gateway to danger pfor a 13-year-old girl. p>> i think that's why she pstarted going to facebook. psomeone to give her attention pand make her feel loved. p>> new details from prosecutors ptonight about the killing of a pvirginia middle school student pwho chatted with her alleged pkiller on an app used by pmillions of american kids. p plus -- p there's a star man p>> the biggest game of the year pfor advertisers. p on my cell phone p>> they're paying a fortune to pgrab your attention for 30 pseconds during the super bowl.

p>> the white and gold dress that pcaused a civil war -- p>> the mystery inside the taco pbox. p>> really? p>> tonight the strategy behind a p$5 million super bowl ad. pbut first the "nightline 5." p>> let's give these dayquil pliquid gels and go. p>> these liquid gels are new, pmousse pmucinex fast max, max strength pand fights mucous. plet's end this. p>> your baby's chubby hand platches onto your fingers so phard it's like she's saying i plove you. pthat's why aveeno's oat formula pis designed for your baby's psensitive skin.

p good evening. pthank you for joining us. ptonight we begin with the pshocking crime that landed two pvirginia tech students behind pbars. paccused of kidnapping and pmurdering a 13-year-old girl. pnow we're learning new details pabout how they allegedly planned ptheir horrifying step by step lot to end the girl's life with pchilling detachment. pabc's eva pilgrim takes us pinside the case. p>> i never had one of my friends pdie. p>> reporter: she was the sweet pvirginia middle schooler found pmurdered. ptonight the details of nicole plovell's short life and gruesome pdeath coming into focus along pwith new concerns about the pdangers of social media. p>> she seems like she was a nice pgirl. pany understanding of why they pbehalf made fun of her? p>> just from her scars. pjust because it's middle school. p>> reporter: nicole faced pterrible medical problems as a pchild. p>> at the age of 10 months old, pcolie received a liver

plife. p>> reporter: the scars were pfading, she was older, making pconnections on social media. p>> that's why she started going pto facebook. psomeone to give her attention, pmake her feel loved. p>> reporter: making that awkward ptransition from childhood to pyoung adulthood and her friend psays she was meeting men online. p>> i found out she was dating a pguy that was over the age of 18. pyou could tell he was way too pold. p>> reporter: shortly after, she psays, another mysterious january man. pjanuary 27th, nicole climbed out pher bedroom window carrying only pher phone and a minion blanket. p>> i have had it to right here pwith people suggesting that this plittle girl is somehow presponsible for all of this. pwhat does she know about pflirtation and dating and sex? pthe girl was lured out holding pon, clutching on to her binky, pher minion blanket. p>> reporter: the police say she psnuck away to meet this man and pwhy wouldn't she have trusted phim?

pstar, good-looking, successful. p>> i realize in the moment that pi am doing things that other eople wish they could be doing. p>> reporter: he'd been on ptelevision. p>> yet i still have goals for pmyself because there are people pwho are better than me. pand i will personally not stop puntil i reach my peak erformance. p>> reporter: nicole never came pback. psoon almost 1,000 volunteers pwere searching and authorities pscoured for leads until they pwere able to track the last pmessages from nicole's phone pleading them to eisenhower. p>> the investigation led us to p18-year-old david e. eisenhower, pa virginia tech student. p>> reporter: with eisenhower in pcustody authorities soon locate pnicole's body, 80 miles away in pnorth carolina. pit's about two miles from a home powned by his extended family. p>> i'm sure that it's something pnicole's family would like to pknow, why did she have to end up phere, left in this condition, pdiscarded in the manner she was? p>> reporter: the investigation

pand arrest what they say is an paccomplice, a friend and another pstudent from virginia tech, pnatalie keepers, charged with phelping eisenhower dispose of pthe body in these woods. p>> i'm assuming that it was robably done after dark and pthey may have thought they were pfurther away from the road than pthey actually are. pbecause there's no lighting out p>> reporter: prosecutors allege pkeepers also helped eisenhower lan the gruesome murder, lotting for weeks, they say pscouting locations, and even pbuying tools. pwhen police showed up to talk to pkeepers, prosecutors say she pimmediately tried to warn peisenhower, texting him p"police." pit was then she allegedly told pfbi investigators eisenhower pkilled noik ankle and put her pbody in his lexus, keepers pallegedly saying she was excited pto be a part of something psecretive and special. p>> that's really a stunning pcomment. pthere is a great deal of pcallousness about that. pshe and eisenhower discussed how pthe murder would be committed, pcutting this little girl's pthroat, as though they're ptalking about an object.

rofiler dr. mary ellen o'toole psaying this is a complicated pcase with multiple motives pspelling disaster. p>> there's synergy that came ptogether that made this a very plethal pair. p>> a very preliminary pdetermination of the cause of pdeath is stabbing. p>> reporter: for nicole's pmother, it's too much to bear. p>> her favorite color was blue. pnicole was a very loveable erson. pnicole touched many people pthroughout her short life. pi can't do that part. p>> reporter: while authorities pwait for the results of an pautopsy they have concluded that pnicole was using a messaging app pcalled kick to communicate with peisenhower, raising questions pabout possibly dangerous pencounters. p>> i'm willing to say kick is a pdevil for young children. pit's like a free ability to ptext. panything you want. arents can't see the phone pnumbers that are coming in and pout.

pthese anonymous apps are popular pwith teens and predators. p>> you can sign up as anybody pyou want to be. pit really becomes a private phunting preserve for some of pthese pedophiles. p>> reporter: here's how kik pworks. pdownload the app for free, add pany name and any photo, send pmessages, photos, and videos, pand you don't even need texting pservice. p>> parents sometimes take away pthese data plans thinking that, pwell, the child has abused it. pbut they only need a wi-fi psignal to be age ble to pcommunicate. p>> reporter: abc reached out to pkik who told us kik cooperated pwith the fbi for their pinvestigation, kik cooperates pwith law enforcement to combat pchild predators anywhere in the pworld, even upon provision of a pcourt order or emergency psituations like this one. psorted by geographic location, pby school, by age. phow do you keep your family psafe? p>> the first thing parents need pto do is set ground rules.

pknow how the parental controls pwork. pthird, they need to talk to ptheir kids, have ongoing pconversations about safety, so pthat kid when it comes time pmakes that safe and smart pdecision. p>> reporter: and it's not just pkik. pthere are many other apps kids pcan use to hide things from ptheir parents. pblogger liz gambener showed pdavid wright how easy it is to phide incriminating photos. p>> when you open it up and i ptype in my password and hit the ercentage sign it's a hidden hoto album. p>> reporter: sending photos as peasy as point and click. pkid swap the files in apps such pas snapchat, kik, yik yak, whis er, making sharing large pnumbers of files fast and easy. p>> kids will always be savvier pthan mom and dad, one step ahead pof us, that's the nature of the pgame. p>> reporter: nicole's friend pcarrie said she tried to tell an padult months ago after she pnoticed nicole was communicating pwith an older man.

pand wrote down his name on a iece of paper and handed it to phim. p>> reporter: the blacksburg olice department denying she palerted the officer about peisenhower saying, had a student por even nicole herself reached pout to him in advance of her pdisappearance about anything pthat could cause concern, he pwould have act the on it through pthe appropriate channeled schannels. p>> no. pi think if he would have done psomething he could have seen the pguys on her facebook and he pcould have stopped all of this. p>> reporter: nicole's family pfiling into court wearing blue pribbons hour before her burial, pmourning a daughter gone too psoon. p>> a preliminary hearing for peisenhower has been scheduled pfor march 28th. p next, inside the super bowl pof advertising. phow madison avenue is rewriting pthe play book book on how americans penjoy the biggest sporting event pof the year. p counting down to tomorrow

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p it's the nfl's biggest game pof the year but it's also the phighest-rated show on ptelevision, making the super pbowl the perfect marriage of psports and media. pthis year's expected to pgenerate, get this, $377 million pin advertising revenue. pand while the stakes are high pfor the teams on the field, they pmay be even higher for the teams pand the ad agencies across pamerica. pabc's nick watt takes us inside psome of the nation's most pcreative minds. p>> reporter: sunday night

p>> caught for the touchdown! p>> reporter: men in tight pants, phard helmets. poff the field in commercial pbreaks there's another just as pintense. p>> america has seen the light! p>> and there's a butt in front pof it! p>> this behind the scenes battle pis between women, men in beards pand buns, working from pindustrial space, doodling. p"madman" was then. p>> this is the greatest padvertising opportunity since pthe invention of cereal. p>> reporter: this is now. pin this battle deploying every pweapon from amusing it girl -- p>> it's not too big. plike you could handle it. p you used to call me on my cell hone p>> reporter: to canadian prappers. p>> these changes don't ruin the psong at all. p>> reporter: recently deceased prock stars. p star man p>> reporter: athletes. p>> you're holding it upside pdown.

p>> reporter: ugly aliens. pand septuagenarian celebrities pwith socks on their hands. p>> there are those who expect pmore. p>> reporter: every slot costs proughly $4.8 million for the air ptime alone. pit's up 75% in just the past 10 pyears. pwhy? pbecause over 110 million will pwatch sunday night. pthe highest-rated show on ptelevision. p>> you're talking about an paudience that is larger than any pother audience out there. p>> reporter: and then the pbragging rights. p>> i've never been a rofessional athlete but i know pwhat it's like to be a rofessional marketer. raising to be on pthe biggest game of the year. p>> reporter: the way doritos pdoes it, competition, a $1 pmillion prize for the best pamateur submissions which they pair sunday night. phere are two of the three pfinalists. pme and the dog the stars in this pone.

p>> exactly, everybody likes pdoritos. p>> competing with huge ads pcreated by mega companies, we pdon't have all that access, so pwe've got 30 seconds to make eople relate and maim peek plaugh and remember it. p>> relate, laugh, remember. p>> yeah. p>> reporter: for the pad-obsessed, youtube offers ptheir ad blitz channel where pfans can watch and vote on their pfavorite commercials. p>> what is up, guys? p>> reporter: videos from social pstars like millennial ava pgutowski part of the draw. p>> it's about the concept. pno matter if you're putting a pton of money mind it or one plittle blog camera, people are pgoing to go to whatever they pwant to watch. p>> reporter: the big dogs also pleverage social media, leaking pteasers, trailers, sometimes the pactual commercials, online ahead pof time. pit's now the norm. p>> when it comes to game day, if pyou've seen this commercial palready you're going to say, pwait a minute, everybody, stop, ut your beers down, check this pout.

pand goliath agency in l.a. p>> doors will open to reveal the pnew optima -- p>> reporter: we'll call them pteam kia. ptheir walken kia spot is already pracking up hits on youtube. p>> what is that? p>> the new kia optima. p>> reporter: in manhattan, team pbud light airing their offering pearly online. p>> so far, so good. pon track i would say. p>> america has seen the light! p>> and there's a butt in front pof it! p>> reporter: now to deutsche in pl.a. p2011, they intentionally leaked pthis gem for volkswagen. pand set a trend. p>> why put it out there before, pwhy not keep it for the super pbowl? p>> we thought, if there's that pmuch thrust irst and hunger for this pcontent, just give it to them, pjust lean into it. pso that blew up huge.

pwas doing that. p>> reporter: but this year they pare team taco bell. pand taking a different tack. p>> the toppings would stay in pbetter if we flipped it. p>> it's become standard now for pbrands to drop their ads early. peverything's out of the bag psometimes a week, two weeks pbefore, you know, the spot even pcomes out. pbut this year taco bell and i pthink a lot of advertisers this pyear have chosen to hold back. pi don't think as many people are pshowing everybody what they've pdone before super bowl sunday. p>> you're holding it upside pdown. p>> really? p>> reporter: there are teasers. pjames harden really does not pknow what he's advertising. p>> taco bell won't talk about pthe product they're launching puntil sunday. pthey won't show the commercial puntil sunday. peverything's a mystery. p>> i mean, how top secret can a ptaco bell product be? p>> you can preorder the product, p700 people as of this morning reordered something they don't pknow what it is. p>> that's genius advertising. pyou're selling something to

p>> you don't know what it is but pyou already want to eat it. reorder now. p>> do you know what it is? p>> no idea. p>> what can they do to a taco? p>> reporter: who wins this and parguably the bigger battle psunday night? pit stands to critics, sales, psocial media reaction, and the plooks on friends' faces. p>> looking around the room pseeing people -- p>> yeah, yeah. p>> if they're actually -- p>> hey, nice, you did pretty pgood, that's great, brad. p>> that's not good. p>> not good, that's the fake pone. pthen there's, "that was good!" pthat's the one i'm looking for. p>> i've got something for you, pgirl. pknowledge. panywhere you want it. p>> reporter: i'm no stranger to pthe ad game. pwe made this for "nightline" a pyear or two ago. plong story as to why. panyway. pto get an idea how this pmulti-million dollar creative rocess begins, a challenge. p>> i'm a very difficult client. pwe have a tv show called p"nightline." pyou need to think of a super pbowl commercial for our tv show.

pyou're all crazy people, throw pthem out. p>> "nightline" is better than pany other show? p>> we are better at topical news pbut funny. p>> do you want to tug at the pheart strings? p>> no, i don't want any pschmaltzy stuff. pi want belly laughs. plike smutty bell -- laughs. p>> if you guys were the first to pcreate an icon outside -- pnontraditional icon, like maybe pa talking cat. p>> reporter: stay with me. p>> do you have an enemy? p>> james corden. p>> seth meyers and james corden. p>> so take down seth meyers. p>> fall asleep to us instead. p>> reporter: is they nowhere pnear as inspiring as christopher pwalken with a sock. phere's why. p>> as much as we'd probably love pto come up with a great super pbowl commercial for you for p"nightline" right at the table ptoday -- p>> it would take eight, nine pmonths. p>> reporter: the goal of every pagency is and forever has been

pthe commercial that started all pthis super bowl commercial pbattle back in 1984. papple. pcan anyone trump it this year? p>> we shall prevail! p>> reporter: schumer perhaps? p>> that's why we're forming the pbud light party. p>> reporter: walken? p>> pizzazz! p>> war hawk, this is good! pdon't know really what it is! p>> reporter: or whatever it is pin that taco box. pi'm nick watt for "nightline" in plos angeles. p next, counting down to the pbattle for the granite state. pwe'll have a preview of tomorrow pnight's final republican residential debate right here pat abc before tuesday's decisive pnew hampshire primary. (music) woman: i' ll never rememberr all the projects, t presentations, or meetings i gave upt

p (music' s drums intensify) but days like this,r i' ll never forget. get out there,p in the 2016 ford escape. t be unstoppable. p this is my fight song p take back my life song v(music) p if you could see your cough, r it's just a cough. you'd see how often yout cough all day p and so would everyone else. new robitussin 12 hour delivers fast, powerful cough relief that lasts up to twelve hours. new robitussin 12 hourt cough relief. nbecause it's never just a cough. hey, need fast heartburnvrelief? 5{ try cool mint zantac. it releases a cooling sensation in your mouth and throat. zantac works in as little as 30 minutes. nexium can take 24 hours. try cool mint zantac. no pill relieves

p hmm hmm hmm-hmm-hmm-hmm p hmm hmm hmm hmm hmm-hmm let us be lovers, we'll marryr our fortunes together t [ cheering ] i've got some real estatet here in my bag counting the carsp on the new jersey turnpike

r [ cheers and applause ] all comer to look for america all comer to look for america to look for america i'm bernie sanders,

the american people can't afford to wait for ideas that sound good on paper... but will never make it in the real world. the grandmother who has to choose between paying for medicine and paying rent... can't wait. the single mom who desperately needs a raise... can't wait. the student with a mountain of debt can't wait. p we can make real progress, r right now for people p and families who need it. p i'm hillary clinton and i

p finally tonight, the race pfor new hampshire and the stakes pcouldn't be higher in the prepublican contest. pdonald trump will be front and pcenter for their final debate pmoderated by our own david muir pand martha raddatz. pgiving us a sneak peek tonight. p>> hey, good evening. pthe excitement is mounting here pat st. anselm college in pmanchester, new hampshire, as pour abc news crew is putting the pfinishing touches on our debate pstage. ptop three candidates -- donald ptrump, ted cruz, marco rubio -- pwill be taking center stage here ptomorrow night and if there's pone thing we can count on it's psome heated exchanges. pall the candidates are gunning pfor momentum. pjust ahead of the crucial new

peverybody wants to make their pmark, survive this debate, and pmove forward. pbut it may be the last chance pfor some. p>> thank you, martha. pmartha and david muir will pmoderate that debate tomorrow pnight at 8:00 eastern, 7:00 pcentral time, right here on abc. pit was former president george ph.w. bush who said, if anyone ptells you america's best days pare behind her, they're looking pthe wrong way. pthank you for watching abc news. ptune into "good morning america" ptomorrow. pas always we're online on our p"nightline" facebook page and pabcnews.com. pgood night, america. phave a good weekend. p pshelley: now at 11:00, some pseacoast towns are cleaning up pover half a foot of snow. pand the wet, pasty snow made

pmike: after a snowy friday,