this is "nightline." tonight, facing a judge, the undocumented immigrant who allegedly shot and killed an innocent young woman out for a stroll with her father and flaming a national debate. why was he here in this country after being deported several times. is it true he found the gun and could this tragedy really have been just a deadly accident? plus actress beverly johnson who claims bill cosby drugged her, speaking out after a document comes to light indicating that cosby admitted in a deposition that he bought drugs intending to give them to young women with whom he wanted to have sex. is this now a vindication? and an underwater adventure. in search of some of the world's

largest sharks and they're doing it without protection. tonight, what they found in an unprecedented american mission into waters off of cuba, but first, the "nightline" five. if you're suffering from constipation or ig irregularity dulcolax is designed for dependable re lief. when salonpas began, it has now evolved into a complete family of pain relievers for targeted relief.

good evening. and we begin here with the

undocumented immigrant accused of murdering a young woman who was just out for a stroll with her dad. the alleged shooter showing his face in court today. this is a case reigniting the long-simmering battle in america over immigration. and tonight here what the alleged shooter is saying and the blame game over whether this horror could have been prevented. today in a courtroom in san francisco, the undocumented immigrant at the center of a horrific murder case and a bitter national debate was formally charged. >> no guilty. >> reporter: the nightmare unravelled on a summer evening last wednesday. >> gunshot wound to the back. >> reporter: kathryn steinle and her father jim were out taking an early evening stroll on san francisco's pier 14 when out of nowhere kate was shot. >> she was fighting no question. >> reporter: kate later died at the hospital. the alleged shooter, a man she

had never met, francisco sanchez, seen here on cell phone video in police custody shortly after the killing. today in court, sanchez, 45 was arraigned on a murder charge and pleaded not guilty. >> this was an accidental shooting. there is no motive whatsoever. >> reporter: sanchez is a citizen of mexico who's been deported from america five times and was arrested on drug charges earlier this year. so why was he released? >> once you've done your time you've done your time. >> reporter: now this seemingly random act of violence has set off a national firestorm about immigration policy and the disconnect between the federal officials who wanted sanchez deported and the local officials who ultimately let him go. >> a mandatory minimum five-year sentence on any illegal alien that's deported and then comes back. >> reporter: despite his plea of not guilty today, sanchez earlier told a reporter this.

>> did you shoot kate steinle? last wednesday? >> yes. >> why did you do that? was that an accident? >> yeah. >> reporter: sanchez says he was delirious that afternoon on some kind of sleeping pills. he says he simply found a gun on a bench at the pier and accidentally fired the shots that killed kate steinle. >> san francisco is a sanctuary city. did you keep coming back to san francisco because you knew they wouldn't deport you. >> yes. >> reporter: and that right there is why this case has become such a flash point. san francisco is known as a sanctuary city. >> three are efforts by local officials to say we think it's more important to be able to develop relationships with undocumented immigrants than it is to report them. >> reporter: the idea is that immigrants are more likely to cooperate with police if their

cooperation doesn't mean they run the risk of deportation. san francisco is one of dozens of major american cities that have enacted some form of sanctuary law. >> the position of those who support these kinds of laws is that we need help solving crimes. we need these people to assist us. >> reporter: officials from immigrations and customs enforcement, also known as ice say they specifically asked in writing to be notified when sanchez's drug case was completed. but they say it needs a warrant. >> this individual came into the country five times, was deported a number of times, so obviously we had issues at the border. but if the local officials had notified ice this individual wouldn't have ended up on the street. >> reporter: with the presidential election heating up donald trump has seized on the case as part of his already incendiary the comments about immigrants. >> they're bringing drugs,

crime, they're rapists, and some i assume are good people. >> reporter: he claims steinles murder proves his point. what do you say to the family of kathryn steinle, killed because we can't secure our border. >> i think trump is preying on fear and using a tragedy opportunistically. >> reporter: hillary clinton is now joining the fray as well. >> how many people running for president on the republican side try to demean immigrants. >> reporter: she has supported sanctuary laws in the past, but today on cnn she said that san francisco officials should have listened to the federal government. >> the city made a mistake not to deport someone that the federal government strongly felt should be deported. >> reporter: this is not the first time that sanctuary laws have been questioned. in 2008 also in san francisco, an immigrant named ramos shot and killed a father and two

sons. ramos had a history as a minor but was shielded by the policy. to be clear, there are no statistics showing that illegal immigrants are more likely to commit crimes than american citizens. in fact illegal immigrants only make up a tiny 3% of america's prison population and there's essentially no correlation between immigrants and violent crime says a study from northwestern university analyzing nationwide statistics. >> politicians love to paint certain groups of people often based on their race, their class and nationality. edwin lee spoke out in defense of the city's law, saying it is not intended to protect repepeat serious and violent felons. we want people to report crime. but today the head of the police union in san francisco seemed to blast both ice and the sanctuary

law. >> if that individual, mr. sanchez, was where he belonged which was in mexico and if he had remained in mexico after he'd been deported five separate times, yes, ms. steinle would be alive today. >> reporter: meanwhile tonight in california sanfrisco sanchez is held on $5 million bail behind bars. his next court appearance is july 27th. ago for kate steinle, her family wants her to be remembered for the person she was, not for the man who took her life. >> kind thoughtful spiritual, deep caring. loving. all those positives. just a beautiful woman. >> reporter: her family says before the shooting she was on her way to visit her brother and sister-in-law who were expecting their first child. >> my baby won't get to meet her aunt. but i hope there's just a little piece of kate's soul when i look in my baby i can remember her.

>> reporter: next on "nightline," the model and actress who accused bill cosby of drugging her, coming forward again tonight after a shocking revelation. what cosby appears to have admitted in sworn testimony, just unveiled. and what some of his defenders are saying tonight. do you like the passaaadd? it's a good looking car. this is the model rear end event. the model year end sales event. it's year end! it's a rear end event. year end, rear end check it out. talk about turbocharging my engine. gorgeous. what kind of car do you like new, or many miles on it? get a $1000 volkswagen reward card on select 2015 passat models or lease a 2015 passat limited edition for $209 a month after $1000 volkswagen bonus. only nexium 24hr gives you nexium level protection for frequent heartburn all day and all night. try nexium 24hr, the #1 prescribed acid-blocking brand, and get all day, all night protection. nexium level protection.

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tonight, we are hearing from one of bill cosby's most prominent accusers in the wake of a blockbuster court document that's come to light saying that cosby bought drugs to give to women with whom he wanted to have sex. >> reporter: for model beverly johnson, one of the two dod women who have accused bill cosby of sexually assaulting or drugging them the news of his admission is a relief. >> i am very happy for the women. i see that a lot of them are relieved and feel vindicated and validated, and that's good. perhaps maybe we can all start a

healing process. >> reporter: last night a sealed court document was made public stating the embattled comedian said yes when asked under oath if he purchased quaaludes to give to women he wanted to have sex with. a lawyer asks him you gave them to other people? cosby answers yes. when you got the quaaludes, was did in your mind that were you going to use these quaaludes for young women that you wanted to have sex with? again, cosby answers yes. the seeming admission released after a judge released the deposition from a 2005 case brought against him by andrea constand accusing him of sexually assaulting her in his pennsylvania home. cosby settled case in 2006 for an undisclosed amount but we were told that the only reason he settled is because it would have been embarrassing in those days to put all those women on

the stand, and his family had no clue. that would have been very hurtful. two months ago i sat down with bill cosby for an exclusive interview. he refused to address the allegations directly. >> it's interesting. this is a situation that's unprecedented. my family my friends, i have been in this business 52 years, and i will, i've never seen anything like this. and reality is the situation. and i can't speak. >> reporter: still, the testimony has refuelled the court of public opinion. >> you know you need the proof. and then i'll be able to give my judgment here or there, and i think -- >> quaaludes to women to have sex. >> in america, still, i know it's a shock, but you actually were innocent until proven

guilty. >> reporter: musician jill scott who's repeatedly defended cosby took to twitter to change her stance tweeting proof will always matter more than public opinion. sworn testimony is proof, completely disgusted. as one of the first successful african-american models beverly johnson became a household name after being feature on more than 500 magazine covers. she was the first african-american woman to grace the cover of vogue back in 1974. but as she transitioned to acting she met bill cosby who she claims drugged her in the '80s when she auditioned for a role on the kogs by show. >> i was invited down to the studio. and then bill cosby asked me to meet at his brown stone to go over the role. >> reporter: in her memoir the face that changed it all, an entire chapter has been devoted to her alleged encounter with cosby.

she shared her story with "nightline" last year. >> i took a couple sips of the cappuccino, and in a second i knew i had been drugged. i feel very lucky that i wasn't raped. i, and i don't think i was raped. but i, i don't know how i got home. i don't know how i got upstairs. i was devastated. i was disappointed. it was almost like a family member had betrayed me. it was such a huge sense of betrayal for me. >> reporter: a barrage of women have recountedilar stories over the years, accusing america's favorite dad of drugging or assaulting them. >> there was a time when i was at dinner at his brown stone, and i had one glass of wine. and the next thing i knew, i was slumped over the toilet,yilet throwing up. i was sick, i was confused.

i was foggy. i had really no idea what was happening. the next thing i remember i was on the couch, and he was removing my underwear. >> he had no right to do that. >> reporter: cosby's legal team has issued a number of denials to these allegations and cosby has never criminally been charged. instead, the subject of a media firestorm. do you feel that the media has been fair? >> let's leave that alone, because that's a fight. >> reporter: okay. >> thank you. >> reporter: it's yet to be seen just how this newly unearthed document will affect the charges against him, but beverly johnson says it's a small victory for her and the other women who allege abuse at the hands of this media titan. are you hopeful this will bring about some charges? >> we have a moment where there is some kind of validation in what they've been saying and what we've been saying. the truth always comes to light.

>> reporter: for "nightline," i'm linsey davis in new york. up next here on a risk emission in the home of the largest sharks on earth, with no protection. abc news "nigh brought to you by progressive. i heard you lost a close one today. look, jamie, maybe we weren't the lowest rate this time. but when you show people their progressive direct rate and our competitors' rates you can't win them all. the important part is, you helped them save. thanks, flo. okay, let's go get you an ice cream cone, champ. with sprinkles? sprinkles are for winners. i understand. guys, it's just the two of you. the setting is just right. but here's the thing, about half of men over 40 have some degree of erectile dysfunction. well, viagra helps guys with ed get and keep an erection.

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finally, tonight it's called the gardens of the queen, but this is no place for a tea party. it's home to some of the largest sharks on earth, and tonight, the explorers who went in there with no protection. >> reporter: these men are in

dangerous waters searching for legendary beasts. the recent political thaw between cuba and america allowing scientists to team up for the first time ever in search of the largest sharks on earth. in fact these waters are where the largest shark on record was caught. a great white said to be over 21 feet and weighing over 7,000 pounds. >> could sharks like this really exist here? could they really be this big? we're here and we're going to head down here to the gardens of the queen. >> reporter: a mission leads them here to the gardens of the queen, called the final frontier of the caribbean, this marine ecosystem is untouched by american researchers. ? this sh a very important place in the garden of the queen. this is a spot where we have catch the largest number of shark. >> reporter: they plan to attach

the sharks' monitors. it is risky. anything could go wrong. ? we're not going to have the gear to stop something like a 21-foot great white shark. we don't have any cages. we know that's part of the reality on this expedition. that we're going to have to jump in and not know exactly ha it is we're going to see. >> reporter: they dive in with nothing to protect them. >> at least a dozen sharks. some of the biggest i've ever seen. >> look at that. >> that is a big mama. >> that's a big female. >> oh, another one. >> reporter: watch as the team tags this massive 19-foot silky shark with their bare hands. >> i did it! [cheers and applause] they did it! >> reporter: next they journey north to the same waters in which el monstro once swam.

finally, the call they've been waiting for. one of the boats has hooked an exceedingly rare long-fin maico. >> it's a long-fin maico! >> all right! look at that beauty! >> you got it! >> reporter: they catch him. >> there you go. >> reporter: tag him. >> good job, good job! >> reporter: and cut him loose. >> get ready. more slack! >> away going to swim? >> all right. there you go man. >> nice. >> so 70 years after el monstro was caught confirm that this is clearly a place where big sharks come. >> reporter: the mission, a success, a partnership born a question not if but when the next one will appear just beneath the surface.

>> only improving my affection for dry land. shark week airs on discovery on sunday. as always we're online 24/7 on our "nightline" facebook page and on abc news.com. thanks for watching and goodnight. that was really a great dinner, huh? yeah, yeah. happy anniversary. hey, you know what i was thinking? since this is our tenth anniversary, why don't we let the kids stay at grandma's and grandpa's all night, if you know what i mean. hey, hey we could watch our wedding video. i guess you don't know what i mean. no! come on.

why? why, why? well, for one thing, watching our wedding video might make tonight seem like a honeymoon. gimme. sit down. you don't know how to use this. you never did, really. can we fast-forward through the chicken dance, please? unless this turns you on. [mumbles chicken dance] you can save that for later. mmm. oh. oh, see, i love this. isn't this romantic? yeah, yeah, yeah. oh, look who i get. what, did you hit something? did you hit something? no, no it's still going. then why am i seeing football? i--i don't know. where did our wedding go?