p this is "nightline." p>> tonight, apple versus the pfbi. pit is an abc news exclusive. pcook. pwhy he is refusing to comply pwith a federal demand to unlock pthe iphone of one of the san pbernardino killers. hone. pthis case is about the future. p>> how it feels to be in the eye pof the storm in a fierce pnational debate over security pversus privacy. p>> it's not just about privacy, pit's also about public safety. p>> and what he has to say about papple. p plus dalia dippolito made

paccused of trying to have her pnow ex-husband killed in an palleged murder for fire plot. pwe're there in court as she pfinally takes the stand. p and an emotional comeback pfor celine dion in her first phusband. pthen the powerful encore. p first the "nightline 5."

p it's dat bate pitting the pfbi over apple. pto be night apple ceo tim cook pon why he is refusing to help pthe feds break into the phone pused by the san bernardino pgunman. p"world news tonight" anchor pdavid muir also gets cook to prespond to calls by donald trump pfor an apple boycott. p>> as we sit here you know some pof the families of the victims pin san bernardino have now come pout in support of the judge's porder that apple help the fbi punlock that iphone. pone family reportedly saying, pwe're angry and confused as to pwhy apple is refusing to do pthis. pwhat would you say to those pfamilies tonight? p>> they have our deepest psympathy. pwhat they've been through, no pone should have to go through. papple has cooperated with the pfbi fully in this case.

pall the information we had on pthis phone. pand we gave everything that we phad. pbut this case is not about one hone. pthis case is about the future. pwhat is at stake here is can the pgovernment compel apple to write psoftware that we believe would pmake hundreds of millions of pcustomers vulnerable around the pworld, including the u.s.? p>> and you'd have to write that psystem in order to unlock that hone? p>> yes. pthe only way we know would be to pwrite a piece of software that pequivalent of cancer. pwe think it's bad news to write. pwe would never write it. pwe have never written it. phere. p>> the fbi though says it pbelieves syed faruk used that pwife, his accomplice. pdo you struggle at all with the ossibility there could be pinformation on that phone that pcould reveal other plots, other eople involved in planning the

p>> david, if we knew a way to pget the information on the phone pthat we haven't already given, pif we knew a way to do this that pwould not expose hundreds of pmillions of other people's pissues, we would obviously do pit. p>> i want to get to what the fbi pdirector james comey said. phe said it's not about a pslippery slope, it's about "14 eople who were slaughtered and pmany more had their lives pruined. pmaybe the phone holds the clue pto finding more terrorists, pmaybe it doesn't. pbut we can't look the survivors pin the eye and ourselves if we pdon't follow any possible lead pdo you understand where he's pcoming from? p>> i do understand where he's pcoming from. pand this is an incredibly pcomplex issue. pthink about this. pif a court compels apple to pwrite this piece of software, to lace a back door in the iphone, pwe believe it does put hundreds prisk. p>> reporter: we asked tim cook

pwould have to create to break pinto the iphone. p>> the pass cord on the front piphones. pafter a certain number of tries pit auto-erases? p>> what they want is they want pus to develop a new operating psystem that takes out the psecurity precautions, then they pwant a ability to go through a pnumber of passwords at the speed pof a modern computer. p>> a computer would do that? p>> a computer would do that. pthat is what they're asking for. pwe believe that is a very pdangerous operating system. p>> you hear that from the prepublican front-runner, donald ptrump -- p>> what i think you ought to do pis boycott apple until such time pas they give that security pnumber. p>> is that the right route in psaying boycott apple? p>> the best thing is -- pamerica's strongest when we all pcome together. p>> is a boycott a way to come ptogether? p>> you know, i think a democracy

pbut this -- i love democracy. pthat is who we are vinita nair. pi think the best thing to do is pto discuss and collaborate and pwork together on whatever the psolution may be. p>> let me ask you this. pyou've invite med to apple pbefore. pthe stories are legendary about pnew products with black drapery pover them, locked doors, psecrecy. pany american company can keep a psecret, it's apple. pto those who might say, why pdidn't the fbi and apple team up pfar earlier in one of those psecret labs and get this done pand no one would have had to pknow about it? ptactics of the fbi. pthey've chosen what they've pdone. pthey've chosen to do this out in pthe public. pfor whatever reasons that they phave. pwhat we think at this point, pgiven it is out in the public, pis that we need to stand tall pand stand tall on principle. pthere's probably more pinformation about you on your hone than there is in your phouse. pour smartphones are loaded with

pfinancial data, our health precords. pthey're also loaded with the plocation of our kids, in many pcases. pso it's not just about privacy, pbut it's also about public psafety. p>> if you didn't think this pwould set a precedent, if you pdidn't believe this would be a pslippery slope, is this psomething your engineers could pit? p>> we've never done it before so pi don't know how long it would ptake. pwould i do it? pin a perfect world where none of pthe implications that i'm ptalking about exist? pyes, we would do it. pwe would obviously do it. pbut we don't live in a perfect pworld. p>> in your quiet moments, do you phave any concern about you might pbe able to prevent a terrorist hone? p>> david, some things are hard. pand some things are right. pand some things are both. pthis is one of those things. p>> in this case, you believe pthere are some things that just pshould never be created? p>> correct. p>> reporter: today steve jobs

pcook says not a day goes by that phe doesn't think about his piconic predecessor. p>> have you thought about what phe would have done in this psituation? p>> steve always did what he pthought was right. pand it is so clear to me that he ploved what america was founded pon so much and would do nothing pto put all these customers at prisk. phe'd be doing the same thing. p>> reporter: tim cook tells us pthey talked to the fbi early on, pgiving them advice, he says, on pother ways to best get pinformation from that iphone, to lug it in, to back it up to the picloud. p>> did they do that? p>> unfortunately, in the days, pearly days of the investigation, pfbi directed the county to reset pthe icloud password. pwhen that is done, the phone pwill no longer back up to the pcloud. pand so i wish they would have pcontact the us earlier so that pthat would not have been the pcase. p>> how crucial was that missed popportunity? p>> very crucial. pthe white house said this week

p"limited in scope." plimited in scope, do you agree pwith that? pand have you talked to the resident on this? p>> i have not talked to the resident. pi will talk to the president. pdo i think it's limited? pno. p>> you have talked to the resident before on these issues pof privacy and security. p>> yes. p>> are you disappointed there pwasn't more of a dialogue with pthe administration before this pswift action from the justice pdepartment? p>> yes. p>> you wish there was more done? p>> yes. pi think there should have been. pthis filing -- we found out pabout the filing from the press. p>> reporter: apple must respond pto the court order by friday. p>> i'm curious, tim. pdid you ever think that you'd pfind yourself at the center of psuch a crucial national debate? p>> no. pthis is not a position that we pwould like to be in. pit is a very uncomfortable osition. pto oppose your government on psomething doesn't feel good.

pwhere we are advocating for pcivil liberties, which they are psupposed to protect, it is pincredibly ironic. p>> david, thank you for that pexclusive report. pin response to our interview ptonight a government official is ptelling abc news that it wants papple to be the only one who pknows how they develop a new way pinto their phones, that the fbi pdoesn't want or need to know pthat secret. pthe debate continues. p up next on "nightline," the pwoman at the center of a psensational case takes the pstand. pdid dalia dippolito high to hire pa hit man to hill her husband? p celine dion singing all by phers in her first vegas concert psince losing her husband. p p all by myself p don't want to be all by myself panymore what if we did for mortgages what the internet did for buying music and plane tickets and shoes? you would turn an intimidating

you could get a mortgage on your phone. and if it could be that easy, wouldn't more people buy homes? and wouldn't those buyers need to fill their homes with lamps and blenders and sectional couches with hand-lathed wooden legs? and wouldn't that mean all sorts of wooden leg-making opportunities for wooden leg makers? and wouldn't those new leg makers own phones from which they could quickly and easily secure mortgages of their own, further stoking demand for necessary household goods as our tidal wave of ownership floods the country with new homeowners, who now must own other things and isn't that the power of america itself now shrunk to fit the hands of a child, or, more helpfully, a home-buying adult. anyway. that's what we were thinking. with my moderate top severe ulcerative colitis, p the possibility of a flarepwas almost always on my mind.

p p p zshe told me x helps people like me x get uc under and keep it x when certain haven't worked humira can lower fight infections, serious, sometimes fatal infections and cancers, including lymphoma, have happened; as have blood, liver, and nervous system problems, serious allergic reactions, and new or worsening before treatment, get tested for tb. tell your doctor if you've been to areas where tcertain fungal infections are common, and if you've had tb, r hepatitis b, are prone to infections, r or have flu-like symptoms or sores. don't start humira if you have an infection. raise your expectations. ask your gastroenterologist about humira. with humira,

p it is the alleged murder for phire case that made national pheadlines. ptonight the woman at the center pof it, dalia dippolito, takes pthe stand with an unusual pdefense. phere's abc ace linsey davis. p>> i'm positive, like 5,000% psure. p>> reporter: dalia dippolito, pthe woman caught on tape saying pshe was 5,000% sure she wanted a phit man to hill her husband, was pback in court yesterday. ptaking the stand for the first ptime since her arrest in 2009 pand her conviction in 2011 -- p>> i have been accused of psomething that i didn't do. p>> reporter: trying to explain paway that incriminating video. pher explanation? pshe was simply acting.

psomething you guys are going to ut online so you can get ublicity? p>> on social media, right. pso he can try to get an acting pjob from it. p>> reporter: dalia says it was art of a plan she hatched with pher then husband michael pdippolito and former lover to pget famous. p>> this is acting? p>> yeah. p>> reporter: prosecutors say pthat was no act. pand allege she promised to pay pthis undercover cop posing as a phit man to kill her husband of psix months. p>> she parked the third space pfrom here. p>> you know, he gets two in the phead. p>> reporter: her now ex-husband pmike dippolito said he couldn't pwait to see what she said in pcourt. p>> let me know, i'll be sitting pin the back with popcorn. p>> walking on the sidewalk, this pdoesn't happen very often. p>> no, it doesn't happen at all. p>> reporter: in an exclusive retrial interview with "20/20" pthis past december dalia pdippolito said she's pmisunderstood. p>> who is dalia dippolito?

pcompassionate. p>> because of that -- p>> reporter: at the time her pnewly hired high-powered pattorneys wouldn't let her talk pabout certain parts of the case, articularly those seemingly pdamning videotapes, because pshe's now facing a new trial pafter her first conviction was poverturned on a technicality. pbut yesterday there was no pavoiding them. pshe's forced to watch that pmoment we've all seen again and pagain. p>> 5,000 percent sure. p>> that's all mohammad told you pto say, right? p>> yes, he told me to say that. p>> 5,000% sure? p>> i needed to project pconfidence. pand yeah. pbut that's what he told me, to pmake it look believable. p>> reporter: perhaps the most psurreal moment in the courtroom, pwhen the prosecutor plays an paudiotape of her trying to pexplain to her then-husband mike pthat she actually didn't pay to phave him killed. p>> please, i need an attorney, pcan you help me? pit's not true. p>> you said you wanted to have

ptrue! p>> reporter: according to her, pmike was in on the performance pfrom the beginning. pso why, asks the prosecutor, is phim? p>> you claim it was all made up, art of a script. phow could that not be true? p>> reporter: her attorney, brian pclaypool, says dalia is the pinnocent victim of a fame-hungry olice department. p>> this case is about a police pdepartment that tossed her under pthe bus for purposes of getting pfame on a "cops" tv show. p>> reporter: the now-infamous pmoment when police staged a fake pcrime scene and told dalia pdippolito her husband was dead. p>> is your husband michael? pi'm sorry to tell you, ma'am, phe's been killed. p>> this special edition of p"cops" is filmed on location -- p>> reporter: he says it's all art of the plan so be on the preality tv show "cops" when pmohammad came to them with the pstory about a beautiful woman pwanting to have her husband pkilled. p>> what the police department

pattractive woman, in their minds pthey're like ching ching ching, pthis is a perfect skit to get on ptape. p>> reporter: not long after pfilming the exchange between the olice and dalia, the police osted the video online. p>> why did you go back to the olice department and pimmediately post, on youtube, a pvideo of the staged crime scene pof dalia dippolito? p>> well, we posted it as part of pour entire plan of publicizing pthe arrest in this case. p>> you agree with me there's pstill a pending investigation on pdalia dippolito and you posted pthe youtube video, right? p>> yes. p>> reporter: dalia's attorney psays it adds up to only one pconclusion, she was framed. p>> there's no question about it, pthat the boynton beach police pdepartment was dead set on pmanufacturing a crime here. p>> reporter: abc news senior plegal correspondent sunny hostin psays that remains to be seen.

p>> do i think that the police pofficers could have done better? pyes. pand you certainly don't as the olice spokesperson upload that pvideo to youtube. pis that a case killer? pno. pit isn't. p>> seems unusual, correct me if pi'm wrong, but for police to lie pon camera and create a crime pscene, make this elaborate pcircumstance to say, oh, your phusband's dead, when he really pisn't. p>> that is unusual but not punheard of. pi have to tell you that sting poperations happen all the time. p>> reporter: the boynton beach olice department stands behind ptheir investigation telling abc pnews -- p>> the "cops" show happened to pbe here at the time of this pinvestigation are we're not in pthe business of producing ptelevision. pwe're in business of saving plives and we believe we did that pin this case. p>> reporter: yesterday issuing a pstatement, we trust in our state pattorney to successfully rosecute this case and we are pconfident we have given his poffice sufficient evidence to

pstill, dalia's attorneys filed a pmotion to dismiss the case based pon evidence of what they say is olice misconduct. pif the case isn't dismissed a pnew trial is set to start this pspring. pand there's one person who says phe has no doubt dalia is guilty. p>> i am 5,000% sure she tried to pkill me. p>> reporter: for "nightline" i'm plinsey davis in new york. p>> thanks to linsey davis. pyou may have noticed sunny phostin providing legal analysis pduring that report. pwe would like to welcome her to pabc news. pshe's joining us as senior legal pcorrespondent and analyst. p up next here, celine dion psinging "all by myself" for the pfirst time since the death of pher husband. p don't want to be all by pmyself dad, you can just droppme off right here. r oh no, i'll take you up totthe front of the school. that's where yourzfriends are. seriously, it's,pit's really fine. you don't want to be seent with your dad? no,pit's..no.. oh, there's\

p [ forward collision warning ] bye dad! the newly redesigned right now you can get a $1,000 presidents' day bonus on new 2015 or 2016 passat, jetta, or tiguan models. red lobster's lobsterfest so come try the largest variety of lobster dishes of the year, like lobster lover's dream or new dueling lobster tails. it's a party on every plate, and you're invited.

p finally, what happened when pceline dion took the stage for pthe first time since the death pof her husband? phere's abc's deborah roberts. p>> reporter: last night celine pdion making an emotional return pto the stage of the coliseum in plas vegas. p with one more look at you p>> reporter: performing "with pone more look at you," a oignant tribute to her late phusband and manager rene pangelil. p>> every time i close my eyes, i pfelt rene on stage with me. phe's always been on stage with pme. pand nothing will ever change pthat. p>> reporter: it's been just a pmonth since she lost her beloved

pbut there was never a question pdion would return. p"my career was in a way his pmasterpiece. pthe idea of leaving it punfinished would hurt him pterribly." p all by myself p>> reporter: a heartbreaking pmoment when dion broke into ptears singing "all by myself." ausing to collect herself pbefore powerfully finishing the pset. pi met dion last spring and pthough angelil was ill, he pjoined us on that very stage. pdespite it all, encouraging his pwife to perform. p>> sometimes, and i think i'm pneed to feel. pjust do it. p>> i did. pbecause i love him. pand i did. pand it was very hard.

pthat love, celine singing once pagain. pfor "nightline," i'm deborah proberts in new york. p>> our thanks to deborah roberts pfor that report. pour thanks to you for watching. ptune into gma first thing in the pmorning. pwe're online 24/7 on our p"nightline" facebook page and at pabcnews.com. pthanks again for watching and pgood night. p pmike: more like spring tonight pas rain, thunder, and climbing ptemps move through. phow much rain to expect, and how pwarm it gets. ptom: the mild weather giving proad crews less wintry mess to pclean up.

pbudget has been used and what pthe surplus might pay. p>> they have to pay attention, pknow their surroundings. pwe want everyone to be safe. pshelley: warm temperatures not pstopping the ice fishing derby pin meredith. pwhy organizers and fish and game psay anglers should be very pcautious out on legs -- out on plakes. ptom: and, super tuesday is less pthan a week away. pthe role one political professor pbelieves 13 states will play in pthe nomination process. p>> no one covers new hampshire plike we do. pshelley: route nine is closed in pstoddard. pnew hampshire dot says the pclosure due to poor road pconditions. ptonight, the state is expecting pheavy rain, even the chance for pa possible thunderstorm povernight. pgood evening, i' m shelley pwalcott. ptom: and i' m tom griffith. ptomorrow temperature will reach pback into the 50' s. plet' s head right over to chief pmeteorologist mike haddad to