this is "nightline." >> tonight, apple versus the fbi. it is an abc news exclusive. one on one with company ceo timy he is refusing to comply with a federal demand to unlock the iphone of one of the san bernardino killers. >> this case is not aboutthis case is about the future. >> how it feels to be in the eye of the storm in a fierce national debate over security versus privacy. >> it's not just about privacy, about public safety. >> and what he has to say about donald trump's call to boycott apple. plus dalia dippolito made national headlines after she wasg to have her

alleged murder for fire plot. we're there in court as she finally takes the stand. comeback for celine dion in her first concert since the death of her husband. "with one more look at you."erful encore.

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it's dat bate pitting the fbi over apple. to be night apple ceo tim cook on why he is refusing to help the feds break into the phone usedrdino gunman. "world news tonight" anchor david muir also gets cook to respond to calls by donald trump for an apple boycott. >> as we sit here you knowilies of the victims in san bernardino have now come out in support of the judge's order that apple help the fbi unlock that iphone. one family reportedly saying,nd confused as to why apple is refusing to do this. what would you say to those families tonight? >> they have our deepest at they've been through, no one should have to go through. apple has cooperated with the fbi fully in this case. they came to us and asked us fore had on

and we gave everything that we had. but this case is not about one is about the future. what is at stake here is can the government compel apple to write software that we believedreds of millions of customers vulnerable around the world, including the u.s.? >> and you'd have to write that system in order to unlock that the only way we know would be to write a piece of software that we view as sort of the software equivalent of cancer. we think it's bad news to write.rite it. we have never written it. and that is what is at stake here. >> the fbi though says it believes syed faruk used that phone to wife, his accomplice. do you struggle at all with the possibility there could be information on that phone that could reveal other plots, other people involved in planning the

get the information on the phone that we haven't already given, if we knew a way to do this that hundreds of millions of other people's issues, we would obviously do it. >> i want to get to what the fbi director james comey sa about a slippery slope, it's about "14 people who were slaughtered and many more had their lives ruined. maybe the phone holds the clue to finding more t doesn't. but we can't look the survivors in the eye and ourselves if we don't follow any possible lead out there." do you understand where he's coming from? >> i do understand where he's coming from. and this is any complex issue. but it is about the future. think about this. if a court compels apple to write this piece of software,k door in the iphone, we believe it does put hundreds of millions of customers at risk. >> reporter: we asked tim cooks new system they would have to create to break into the iphone.

like we all use to get into our iphones. after a certain number of tries it auto-erases?nt is they want us to develop a new operating system that takes out the security precautions, then a ability to go through a number of passwords at the speed of a modern computer. >> a computer would do that? >> a computer would do hat they're asking for. we believe that is a very dangerous operating system. >> you hear that from the republican front-runner, donald trump -- >> what i think you ought to do is boycott time as they give that security number. >> is that the right route in saying boycott apple? >> the best thing is -- america's strongest when we all come a boycott a way to come together? >> you know, i think a democracy

but this -- i love is who we are vinita nair. i think the best thing to do is to discuss and collaborate and work together on whatever the solution may be. >> let me ask you this.o apple before. the stories are legendary about new products with black drapery secrecy. any american company can keep a secret, it's apple.ht say, why didn't the fbi and apple team up far earlier in one of those secret labs and get this done and no one would have had to know about it? >> i can't talk abouof the fbi. they've chosen what they've done. they've chosen to do this out in the public. for whatever reasons that they have.this point, given it is out in the public, is that we need to stand tall and stand tall on principle. there's probably morebout you on your phone than there is in your house. our smartphones are loaded with our intimate conversations, our

cases. so it's not just about privacy, but it's also about public didn't think this would set a precedent, if you didn't believe this would be a slippery slope, is this something your engineers could do and how quickly could they do>> we've never done it before so i don't know how long it would take. would i do it? in a perfect world where none of the implications that i'mt? yes, we would do it. we would obviously do it. but we don't live in a perfect world. >> in your quiet moments, do you have anyht be able to prevent a terrorist attack by breaking into that phone? >> david, some things are hard. and some things are right. and some thingsone of those things. >> in this case, you believe there are some things that just should never be created? >> correct. s would have turned 61. cook says not a day goes by that

iconic predecessor. >> have you thought about what he would have done in this situation? >> steve always did what he was right. and it is so clear to me that he loved what america was founded on so much and would do nothing to put all these custo he'd be doing the same thing. >> reporter: tim cook tells us they talked to the fbi early on, giving them advice, he says, on other ways to best get iphone, to plug it in, to back it up to the icloud. >> did they do that? >> unfortunately, in the days, early days of the investigation,ed the county to reset the icloud password. when that is done, the phone will no longer back up to the cloud. and so i wish they would have contact the us that would not have been the case. >> how crucial was that missed opportunity? >> very crucial.

that the fbi's request is limited in scope, do you agree with that? and have you talked to the president on this? >> i have not talked to the talk to the president. do i think it's limited? no. >> you have talked to the president before on these issues of privacy and security. >> yes. >> are you sn't more of a dialogue with the administration before this swift action from the justice department? >> yes. >> you wish there was more done? >> yes.ere should have been. this filing -- we found out about the filing from the press. >> reporter: apple must respond to the court order by friday. >> i'm curious, tim. did you ever thinkfind yourself at the center of such a crucial national debate? >> no. this is not auld like to be in. it is a very uncomfortable position. to oppose your government on something doesn't feel good. and to oppose it on

civil liberties, which they are supposed to protect, it is incredibly ironic.or that exclusive report. in response to our interview tonight a government official is telling abc news that it wants apple to be the only one who knows how they develop a newheir phones, that the fbi doesn't want or need to know that secret. the debate continues. up next on "nightline," the woman at the center of a sensational case takes the stand. didlito high to hire a hit man to hill her husband? celine dion singing all by hers in her first vegas concert nd. all by myself don't want to be all by myself anymore f we did for mortgages what the internet did for buying music and plane tickets and shoes? you would turn an intimidating

phone.uld be that easy, wouldn't more people buy homes? and wouldn't those buyers need to fill their homes with lamps auches 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 whichuickly 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 homeownerngs and isn't that the power of america itself now shrunk to fit the hands of a child,, a home-buying adult. anyway. that's what we were thinking. th my moderate to severe ulcerative colitis, the possibility of a flare was almost always on my mind.

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it is the alleged murder for hire case that made national the woman at the center of it, dalia dippolito, takes the stand with an unusual defense. here's abc ace linsey davis., like 5,000% sure. >> reporter: dalia dippolito, the woman caught on tape saying she was 5,000% sure she wanted a hit man to hill her husband,rt yesterday. taking the stand for the first time since her arrest in 2009 and her conviction in 2011 -- >> i have been accused ofn't do. >> reporter: trying to explain away that incriminating video. her explanation? she was simply acting.

put online so you can get publicity? >> on social media, right. so he can try to get an acting job dalia says it was part of a plan she hatched with her then husband michael dippolito and former lover to get famous. >> this is acting?>> reporter: prosecutors say that was no act. and allege she promised to pay this undercover cop posing as a hit man to kill her husband of six she parked the third space from here. >> you know, he gets two in the head. >> reporter: her now ex-husband mike dippolito said he couldn't wait to see court. >> let me know, i'll be sitting in the back with popcorn. >> walking on the sidewalk, this doesn't happen very often. >> no, it doesn't happen at all. >> reporter: in an eerview with "20/20" this past december dalia dippolito said she's misunderstood. >> who is dalia dippolito? >> understanding, sweet,

newly hired high-powered attorneys wouldn't let her talk about certain parts of the se seemingly damning videotapes, because she's now facing a new trial after her first conviction was overturned on a terday there was no avoiding them. she's forced to watch that again. >> 5,000 percent sure. >> that's all mohammad told right? >> yes, he told me to say that. >> 5,000% sure? >> i needed to project confidence. and yeah. but that's what he told me, to make it look reporter: perhaps the most surreal moment in the courtroom, when the prosecutor plays an audiotape of her trying to explain to her then-husband mike that she have him killed. >> please, i need an attorney, can you help me? it's not true. wanted to have me killed, i heard that. >> it's not true, that is not true!

mike was in on the performance from the beginning. so why, asks the she trying so hard to convince him? >> you claim it was all made up, part of a script. how could that not be true? >> reporter: her attorney, brian claypool, says dalia is the of a fame-hungry police department. >> this case is about a police department that tossed her under the bus for purposes of getting fame on a "cops" tv >> reporter: the now-infamous moment when police staged a fake crime scene and told dalia dippolito her husband was dead. >> is your husband michael? i'm sorry to tell you, killed. >> this special edition of "cops" is filmed on location -- >> reporter: he says it's all part of the plan so be on the "cops" when mohammad came to them with the story about a beautiful woman wanting to have her husband the police department did is found out she's an

they're like ching ching ching, this is a perfect skit to get on not long after filming the exchange between the police and dalia, the police posted the video online. >> why did you go back toartment and immediately post, on youtube, a video of the staged crime scene of dalia dippolito? >> well, we part of our entire plan of publicizing the arrest in this case. >> you agree with me there's still a pending investigation on dalia dippolito and you posted the youtube video, right? >> reporter: dalia's attorney says it adds up to only one conclusion, she was framed. >> there's no question about it, that thedepartment was dead set on manufacturing a crime here. >> reporter: abc news senior legal correspondent sunny hostin says that remains to be case of entrapment? >> do i think that the police

yes. and you certainly don't as the police spokesperson upload that tube. is that a case killer? no. it isn't. >> seems unusual, correct me if i'm wrong, but for police to lie and create a crime scene, make this elaborate circumstance to say, oh, your ly isn't. >> that is unusual but not unheard of. i have to tell you that sting operations happen all the time. police their investigation telling abc news -- >> the "cops" show happened to be here at the time of this investigation are we're not in the business of producinge in business of saving lives and we believe we did that in this case. >> reporter: yesterday issuing a statement, we trust in our state attorney to successfullyase and we are confident we have given his office sufficient evidence to

still, dalia'son to dismiss the case based on evidence of what they say is police misconduct. if the case isn't dismissed a new trial is set to start this spring. and there's one person who says dalia is guilty. >> i am 5,000% sure she tried to kill me. >> reporter: for "nightline" i'm linsey davis in new york. >> thanks to linsey davis.iced sunny hostin providing legal analysis during that report. we would like to welcome her to abc news. she's joining us as senior legal correspondent and analyst. up next here,nging "all by myself" for the first time since the death of her husband. don't want to be all by myself dad, you can just drop me off right here. oh no, i'll take you up to the front of the school. that's where your friends are. seriously, it's, it's really fine. you don't want to be seen with your dad? no, it's..no.. oh, there's tracy.horn honking ]

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finally, what happened when celine dion took the stage for the first time since the death of her husband?roberts. >> reporter: last night celine dion making an emotional return to the stage of the coliseum in las vegas.ne more look at you >> reporter: performing "with one more look at you," a poignant tribute to her late husband and manager rene >> every time i close my eyes, i felt rene on stage with me. he's always been on stage with will ever change that. >> reporter: it's been just a month since she lost her beloved husband to throat cancer.

dion would return. "my career was in a way his masterpiece. the idea of leaving it unfinished would hurt him terribly." all by myself >> reporter: a heartbreaking moment when dion broke into tears singing "all by myself." pausing to collect herself before powerfully finishing the set. i met spring and though angelil was ill, he joined us on that very stage. despite it all, encouraging his wife to perform.hink i'm used to it, don't feel what you need to feel. >> go on and i did. and it was very hard. as a tribute to

again. for "nightline," i'm deborah roberts in new york.nks to deborah roberts for that report. our thanks to you for watching. tune into gma first thing in the morning. we're online 24/7 on ourk page and at abcnews.com. thanks again for watching and

hollywood, almost live. it's comics th your host, byron allen. tonight, byron welcomes andy vieira. aaron jackson. and paul w, the man who thinks that video games will be very popular one day, byron allen! >> yeah! yeah!