this is "nightline." >> tonight, breaking news. a rescue diver has died in the effort to save the 12 boys and their soccer coach trapped in that cave in thailand for two weeks. what went wrong and the latest on the rescue mission. plus maze of madness. a murder mystery unraveled through the eyes of a police chief. >> i just sat back in my chair listening and thinking, this can't be. >> a love triangle, homicides, and accusations of cannibalism. >> well, it was definitely something i never ate before. it was like a transparent kind of meat. >> the cunning plan to trick a su killer into confessing. and a husband and wife's twisted secret exposed. and inside giphy.

the $600 million team putting out nearly every gif on the internet. critics point to some people using popular gifs of oprah and real housewives. >> when you represent people in cookie cutter ways that looks like racism. >> first the "nightline 5." >> when i received the diagnosis i knew at that exact moment, i'm beating this. my main focus was to find a team of doctors. it's not just picking a surgeon, it's picking the care team and feeling secure where you are. >> visit carrycenter.com/breast. overwhelming air fresheners can send you running. try febreze one with no aerosols or heavy per soups so you can spray and stay. febreze one. >> and number one is coming up >> and number one is coming up in just 60 seconds. at ikea, we believe your perfect student deserves the perfect room for the perfect price. and... who's there? hey. a boy? you never told your dad and me about any... wait, what's going on now?

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good evening. we begin tonight with breaking news. a sad development in thailand where 12 boys and their soccer coach are trapped in that cave. they've been in there for two weeks now. and tonight we are learning that a rescue diver, a former thai navy s.e.a.l., has died while working to deliver supplies to the team. the diver passed out and died from a lack of oxygen while on a mission supplying oxygen canisters. his death raises fears about the dangerous path to safety for these boys who have no diving experience. at a news conference, a local commander said despite this death, they will continue and they will accomplish their mission. we will have much more on this breaking story first thing in the morning on "gma." we turn now, though, to a twisted murder mystery. this case involves a married couple accused of unthinkable crim aeged cannibism. it a ts back to their bizarre prewedding pact.

here's abc's linsey davis. >> what would the biggest piece of bone be that you -- i mean -- >> torso. >> torso? >> reporter: kelly cochran, in handcuffs, is leading iron county police chief rizzo to a breakthrough, all caught on body cam. >> she's saying everything is here, the skull -- >> reporter: a man named christopher regan has been missing for 18 months and kelly is the only person alive who may know what happened. >> dog's indicating. >> that's what it does? >> yep. >> without indication as to where kelly had just shown me, the dog went directly to that tree and indicated the scent and the source of human remains. >> reporter: for nearly two years, chief rizzo doggedly pursued this case that made headlines. brutal murders. allegations of cannibalism. and a cat and mouse hunt for justice across several states. this became your life?

>> it did. >> it consumed you? >> it did. >> oh my god! >> reporter: chief rizzo's hunt for the truth is showcased in a two-part investigation discovery series "dead north" which weaves hours of real police body cam and tear deviation footage with glossy re-enact manies. >> it's not a missing person case, this is a murder. >> reporter: it michigan's upper peninsula, october 2014, christopher regan is recorded missing from iron county. chief rizzo is on the case and learns regan has been sleeping with a married woman named kelly cochran. she questions kelly and husband jason and sees red flags right away. what's your initial reaction when you meet them? >> watching and listening to the interviews, you know, at that point i knew that there was -- something wasn't right, there was most definitely a possibility of their involvement. >> hi, i'm chief rizzo with iron county police, nice to meet you -- >> reporter: chief rizzo wonders if jealousy over the affair may have something to do with the missing man.

she eventually gets a search warrant to enter the cochran house. police gather evidence. but make no arrests. then, under the cloak of darkness, the cochrans flee to indiana. >> normal people pack their things and take them, they don't just leave everything behind. which is what they did. >> reporter: the neighbors they left behind in michigan tell chief rizzo the cochrans began behaving strangely around the time chris regan went missing. using power tools in the middle of the night. then came an invitation for dinner. >> kelly and jason asked if i want to come over for dinner one night. i was like yeah, sure. this is two days after chris was

missing. >> all of a sudden, in one week, they're having them over to their house for dinner. and they've got all this meat. how'd they get all that meat, where'd they get the money for it? >> it was definitely something i never ate before. it was like a transparent kind of like meat. like a lobster or shrimp. >> how much more disturbing did that make this whole scenario? >> that was the first time i was ever brought to think that they could have dismembered him. i just sat back in my chair listening and thinking, this can't be. >> reporter: while michigan authorities struggle to make headway in chris regan's disappearance, across state lines in indiana, authorities receive a phone call that sparks their own investigation. >> lake county 911.

>> reporter: again, kelly cochran is at the center of it. she calls 911 about her husband, jason. >> his face is like blue, he's breathing barely, i don't know what's wrong. >> reporter: jason cochran ends up dying. >> i kept thinking that something was going to happen. either he's going to kill her and kill himself, or -- i just kept thinking someone's going to end up dead. and it happened. >> reporter: the autopsy report rules jason's death a homicide. toxicology showed a large amount of heroin in his body. but he had been suffocated before an overdose could kill him. now that signs point toward kelly being involved in her husband's death, hobart indiana detective jeremy ogden sees an opportunity to get kelly talking. >> you can help with things to do with that as a witness, not a suspect. >> reporter: he hopes this case will lead to answers about what happened to chris regan too. >> i wanted all the pieces of the puzzle to come together. i knew from the beginning that

the only way to solve both of these murders was to get her to admit what happened to chris regan and disclose the location of chris regan. >> reporter: detective ogden comes up with a plan to spook kelly using a close friend of jason's named walt ammerman, calling with a red herring, pretending her husband jason mailed him a letter before his death. >> you could take all the acting classes in the world and it's not going to prepare you for that. >> very nervous. >> the note says, if something were to happen to me, please send this in a few weeks, do not open it. and there's an envelope in there with no return address. to the iron river police department. it's like i'm supposed to mail this, but i just wanted to tell you. >> uhh -- please don't. >> you hear her with this big sigh, and then she kind of starts to suck it back up and

gain composure again. the next thing you know it's, do what you have to do. >> reporter: kelly cochran almost immediately reaches out to detective ogden. she's ready to drop a bombshell about chris regan's disappearance. >> what happened? what happened? how? what did he do with chris? >> cut him up. >> reporter: kelly claims that her husband shot chris regan as part of a marriage pact the couple made. >> finally got her to admit that, you know, she lured chris regan to the house. she said that her and jason had this pact on the night of their wedding, if one cheated on the other, that it was the responsibility of the one who cheated to kill their lover. if they didn't do it, that the spouse could then k arrested. police look to her to help find the body. >> help bring chris home. i want something of chris' so his kids can bury him and have a

proper service. >> reporter: kelly agrees to take chief laura rizzo to where his body parts are buried. and there the cadaver dog detects the scent of human remains on a plastic bag. >> i would say probably 600 yards or so from where that bag was found, ultimately the dog ends up in this open field and there's the skull laying right in the middle of the field. >> what was that moment like for you? >> indescribable, really. i felt like -- for a minute like -- you know, is this really happening? is it really him? i mean, you're just kind of thinking, i've been looking for so long and thinking i'm never going to find him. >> cochran is charged with homicide in connection to regan's death -- >> reporter: kelly cochran stands trial for chris regan's murder. although she admits involvement, she pleads not guilty. >> i felt guilty for chris not

being here and prevent that. >> reporter: she is convicted. >> kelly cochran guilty on all charges -- >> reporter: later she pleads guilty to killing her husband, but both chief rizzo and detective ogden, who interviewed her many times, believe kelly might be guilty of much more. do you think she's responsible for more than two murders? >> absolutely. the way she controlled herself, the education she gave herself to do these things and get away with them. >> you think she's a serial killer? >> yes. >> how many people? >> i don't know the number. it's not as great as what she's claimed. she claimed at one time she killed 21 people. >> reporter: kelly cochran is now serving a life sentence. jail for life? >> forever. >> how do you feel about that? >> i'm very glad that she's there. and i mean -- there's others like her out there. but at least she can't hurt anyone else. >> reporter: for "nightline," i'm linsey davis in new york. >> you can watch all of "dead

north" on investigationdiscovery.com. next on "nightline," cultural appropriation in three seconds or less. why some critics say gifs are encouraging people to stereotype. stuffy? e still smell that's because your home is filled with soft surfaces that trap odors and release them back into the room. so, try febreze fabric refresher. febreze finds odors trapped in fabrics and cleans them away as it dries. use febreze every time you tidy up to keep your whole house smelling fresh air clean. fabric refresher even works for clothes you want to wear another day. make febreze part of your clean routine for whole home freshness. (vo) imagine a visibly healthin 28 days. purina one. natural ingredients, plus vitamins and minerals in powerful combinations. for radiant coats, sparkling eyes, and vibrant energy. purina one. 28 days. one visibly healthy pet.

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to the headquarters of a gif giant. they're used in almost everything we do. gifs are a cultural obsession. >> there are thousands of ways to express yourself in three frames or less. most of us have seen the more famous gifs, like this one, "white guy blinking." or "crying michael jordan." some critics are concerned communicating in short form leads us to stereotype and generalize entire swaths of the population, seen by some as a form of cultural appropriation. this "new york times" video examined how gifs and memes can be a digital blackface. >> women of color in particular are called on frequently to express emotions for us. >> reporter: writer lauren michelle jackson says people outsource their emotions to giffs, in particular gifs of women of color such as oprah or the real housewives. >> you're sass, you're delight. >> the internet likes things that are exaggerated.

and so when you already have a group of people that are stereotype for being over the top, you know, you meet that with the internet and it goes viral all the time. >> reporter: she wrote about this in an article for "teen vogue" urging users to be cognizant of what we share and how we share. >> when you start to represent people in cookie cutter ways and they're not afforded the full range of humanity, i mean, that is racism. that looks like racism. >> reporter: the largest purveyor of gifs worldwide is a company called giphy. over 300 million people use its platforms every day to send and share gifs and memes. they say they too have had to confront this idea of digital blackface. you think it's a trend? >> any time there's culture put out, other cultures will appropriate the culture. at some point it becomes part of mass culture. there is a responsety for media companies to look at what they're doing and how they are a citizen in this kind of

community. >> reporter: these guys, who may look better suited to making artisanal chocolate, are the cofounders of a burgeoning tech giant worth an estimated $600 million. you can't tell people what gifs they can use? >> no, but we can try to -- >> we can. >> -- to make sure we have the best types and representative gifs across all types of interests. >> reporter: after this racist meme found its way onto the platform the company had to make changes. how did that happen? >> that was a bug in our moderation filters. once we were alerted to that content we took it down immediately, within minutes. we did an entire review of our moderation system. >> people can't get into your system if they're putting out rationally charged -- >> no. >> reporter: the first gif to go viral was the dancing baby. now there are millions of them. part of the reason, experts say, for the explosion in popularity in gifs is human impatience. scientists say the average human attention span for any one thing

is 12 seconds. are you sure, though, thatnd sh and shorter is an unalloyed positive? >> i think there's a lot of concerns on the internet. if you think about the average time anybody's watching video online, it's really small. good or bad? i don't know yet. >> it's a massive science experiment. >> yeah, that we're conducting in realtime. >> i think it's really more about the content being delivered. >> reporter: sherry turkel is a psychologist who studies people's relationships with technology. she thinks gifs are leading us to forget the art of real conversation. >> so gifs are a great language for some things. a terrible language for others. the trouble is you start to get attached to your gifs and you can forget how much you're not communicating. >> this is a fake noadcast we d a tion, they're tryg to add to it. there are subtle, complex decisions you face all the time that i don't know that a gif is going to help you with.

>> certainly isn't to say, discussing some very, very delicate nuance is going to go out the window and get solved with a gif. maybe it will. it's totally possible. but we're not trying to replace things that are really, really useful, we're trying to add to the new ways that people are using technology. >> what's the business model here? how do you make money? >> at our core, we're a search company. paid search and promoted search. >> reporter: in their studios in new york city and los angeles, they have celebrities come by and create original content. they even let me give it a try. >> do you have mantras or things like that? >> peace. >> reporter: somewhat lamely. this is vegan leather? there's going to be hell to pay. i'm texting my wife. where i would see it? the guys still had to teach me how to text gifs to my wife. i can't believe i let you guys take over communication with my

wife. >> i'm sorry to dan's wife, we think you're great, and you are now part of a live television story. >> reporter: she thought someone stole my phone. >> what is happening, she wrote, she's calling me. >> better hang up. >> i'm doing a story at a company called giphy, they make gifs. >> sorry. >> reporter: hopefully gifs will not replace books or television or heaven forbid actual human interaction. but they are an important part of our digital landscape and mi news anchors, should know about them. next here, they dance like no one was watching. and now it's gone viral. this is a cell. so are all these. they work together, doing important stuff...

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finally here tonight, you might call it a random act of rhythm. when officer sandy fernandez spotted this little girl sitting on the sidelines in her wheelchair during a quintera, he

asked her to dance. the deejay captured it on video and his post went viral. the officer even recorded a message for the young girl and her family to put a smile on her face. her name is saria, 5 years old, she suffers from spina bifida. saria clearly loves to dance. we're told she will be meeting officer fernandez again for lunch and another spin. and maybe that too will go viral. thank you for watching "nightline" tonight. as always we're online 24/7 on our "nightline" facebook page. thank ♪ strummed guitar you can't experience the canadian rockies through a screen. you have to be here, with us.

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