this is "nightline." tonight, the fallout from the killing of a 450 pound endangered guerilla to save a toddler. new details on the investigation. the online mom shaming and many wondering did the silverback have to die? not happy with donald trump? for hillary clinton, could this be a moment for the third party to rise up? meet the libertarian. go inside the libertarian convention but are they more burning man than commander and chief. she lost her arm in a shark attack and was back on the water in less than a month and now she's crushing the waves and the competition.

but first, "the nightline five." >> covering is caring because covering heals faster. for a bandage that moves with you and stays on all day, cover with a band-aid . number

♪ good evening and thank you for joining us. we begin after the backlash of a killing of a silverback named

horambe at a san diego zoo. he's seen grabbing the toddler. tonight, the boy's mother under investigation and many are asking did horamb ire have to d? >> reporter: the images jaw dropping. tonight, a viral mix of out rage and mourning, focussed on this 17-year-old endangered silverback guerilla, whose death at the hands of cincinnati zoo officials has caused a fire storm of back lash. >> he died at no fault of his own. >> i'm sorry, when you have animals, everything should be shot. there should not be a way for a kid to climb up and over, there just should not be a way. >> the child's life was in danger. second guessers don't understand that you can't take a risk with a silverback guerilla.

>> reporter: many are placing the death squarely on the parents. a scene unfolding on saturday, 10 minutes of desperate horror. the boy's mother helpless from above. athortuthorities say the child climbed over the barrier and climbed through bushes before getting through the mote. and a three foot high railing that separates the crowd from the exhibit. >> and a 3-year-old child has fallen into the guerilla cage. >> reporter: suddenly onlookers scream as the boy is dragged and grabbed through the water. >> this child was being dragged around, his head was banging on concrete. >> i heard the kid crying. i think the guerilla was reacting to everybody's panic. everybody else screaming.

>> reporter: at one point, the primate stops and appears to hold the child's head, later propping the boy up from behind and eventually dragging him all the way to the other side of the inclosure. >> he then went around the corner and that's when everybody got there and started evacuating, telling people they needed to get out of the area. >> reporter: it's what you don't see here, an off camera decision being made by zoo officials to end it. >> you could tell it was a high powered rifle. my heart sank. i knew at that moment what had happened. >> reporter: horambe the guerilla who celebrated his 17th birthday on friday, dead. the zoo defending its decision not to use a tranquilizer. >> in the real world you make difficult calls. i'm proud of the team that handled it. >> reporter: the child was

immediately rushed to the hospital, reportedly with a concussion. he's now safe and back home with his family. the horrific ordeal over, but the backlash just beginning. >> it's heart breaking. even talking to you right now, i'm ready to break out in tears. >> reporter: today zoo staffers working on the inclosure. >> we're here to give -- to remember this animal that died and our hope is through his death, there will be more of an awareness and perhaps something like this won't happen again. >> reporter: online, reaction was swift and immediate. celebrities weighing in. the guerilla's death making headlines on "the view" today. >> i would maybe rally everied

bey, le -- everybody, go in there. >> even if it a kid creepy crawls away from you, there should never be a way for a child to get in there. >> reporter: this almost reminiscent of the internet fuelled fire storm of the death of cecil the lion at the hands of an american trophy hunter which sparked a massive public shaming. and animals from other zoos say the difficult situation was handled correctly. >> unfortunately, when we're talking about a large silverback that is showing aggression, there was no other decision. >> reporter: noting that while tragic for the animal, the child's life was at stake. >> i'll bet my life right now, that child would not be here today and you wouldn't want to see this on any tv show. >> reporter: the only word from

the parents, a now deleted facebook post. >> i think boys' parents are taking the bulk of the blame for this. this is a sad, terrible thing that happened. there weren't easy answers at the time they decided to pull the trigger. >> reporter: a brooklyn mom who wrote this post after being disgusted by what she sees as outicized parental back lash. >> even the most vigilant parents are at risk of losing their kids now and then when they're out with their kids. there's no right amount of parenting. if you do too much, you're criticized. if you do too little, you're criticized. really, parents can't win. >> reporter: you see a guerilla carrying an injured boy who had fallen into an inclosure to zoo

keepers for help. >> there's way too many ifs. it's what you call a no-win situation. sglerks but the >> reporter: 2007 when a 350 pound siberian tiger got out of her habitat at the san francisco zoo. the tiger immediately killed a 17-year-old carlos jr. and injured two of his friends. just last month this woman nearly lost her life trying to grab a fallen hat from a tiger pen at the toronto zoo. luckily neither woman or animal was hurt. it's easy to forget the sheer power of these beasts. harris travelled to south africa to see silverback guerillas like horambe. todd is a wildlife researcher who has dedicated her life to endangered animals.

but kwi . >> i think it's hard for you to imagine how agresz gressive thet to be. he's got huge teeth and extremely strong. >> reporter: for tautd todd, a delicate dance between friend and faux. and so many are turning out to mourn and protest the death of this magnificent beast. they're still reviewing the facts and circumstances that led to the incident. the zoo saying they're investigating what changes need to be made to stop saufuch a tragedy from happening again. next, a political convention featuring "star wars" characters and merlin supreme. this is a real political party, one that could potentially play a decisive role in this

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prosspect of an independent candidate. >> there's a part that is thought committed to donald trump. >> reporter: drawing an instant sneer today from trump. crystal is right about one thing, 2016 won't just be a choice between clinton and trump. >> the nominee for president of the united states, governor gary johnson. [ applause ] >> reporter: meet gary johnson and his running mate, bill well, the newly minted libertarian party ticket. they locked up the nomination sunday in orlando. he was the governor of massachusetts in the early '90s. >> i feel the government should do a very few things but do them well. >> reporter: he was the republican governor of new mexico in the '90s. >> i'm grateful to be in a position to make a difference, a positive difference in people's lives. >> reporter: sensing an opening

for someone like them in 2016. >> when cruz dropped out, my google hits went up 5,000%. >> reporter: but the libertarian party is unorthodoxed to say the least. is this a libertarian voter? how are you? do you know gary johnson. >> how are you? >> reporter: not likely to run into a jawa from tatarine at a democrat or republican convention. one candidate actually performed a strip tease, baring it all for the party. this weekend's convention took place in the shadow of mega-kon. so, everything once in a while you'd see swamp thing or a wizard from hog warts. as political conventions go,

this was like from star wars. . vermin supreme, and star child, the one in the transparent raincoat. >> transpartsent, not bipartisan, transpartisan. >> reporter: they're serious people who believe in small government full stop, lower taxes, fewer regulations, more freedom. >> we're looking at the likelihood of a very close race between two historically unpopular candidates. how does the libertarian party play in that mix? >> at the end of the day, i think it's equally from both sides. >> reporter: and fiscal conservatism is going to play well with republicans, especially moderate republicans. >> the raungleonald regan of mes

going to have to say tear down this wall. >> i don't think they have a shot of winning but i think they have a shot at affecting the voters. >> reporter: a new poll puts johnson's chances at 5%, compared to 37% for clinton and 30% for trump. if the libertarians can boost their polling up, they meet inclusion in the presidential debates, exposing them to a much bigger audience. >> we need to get to 15%, then put money in the kitty, so people know we're serious about being competitive. >> i think the majority of the people in this country are libertarian and they just don't know it. >> mied idea of a perfect government is one guy who sits in a small room at a desk and

the only thing he's allowed to decide is who to nuke? >> when government fears its citizens, libberty thrives. when citizens fear government, that's tyranny. >> reporter: it has the potential to grab votes from both sides of the aisle. providing a home for dissolutioned democrats and wooful republicans alike. >> there's potentially going to be a lot of broken hearted bernie sanders voters looking for a place to go? >> all the social issues, marriage equality, legalized marijuana, let's stop dropping bombs, crony capitalism is alive and well, but when we get to the tee in the cross roads in economics, he goes one way, and we go the other. >> reporter: the more successful they are, the more they could be a wild card.

in 2000, ralph nadir got enough votes to throw the election to george w. bush. does any part of you worry you could go douwn as the ralph nadr of 2016? >> not a bit. >> reporter: several of the folks in full costume told us they won't be voting for clinton or trump. >> trump and hillary are definitely no go for me, 100%. >> i'm voting for gary johnson. >> reporter: you're voting for gary johnson? >> there's nowhere else to go. >> reporter: plenty of comic books feature superheroes with unlikely origin stories and in the libertarian party, even in these costumes, these folks fit

right in. david wright. next, she lost her arm in a shark attack at age 13 and was back on the board in a month. and wait until you see what she's done now. abc news "nightline" brought to you by nissan. ♪ ♪ take on the unexpected with a car that could stop for you. nissan safety shield technologies, available in the altima, sentra and maxima. trust number one doctor recommended dulcolax constipated? use dulcolax tablets for gentle overnight relief suppositories for relief in minutes

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♪ and finally here tonight, you may remember the young female surfer who lost her arm to a shark and got right back in the water. well, tonight she's wowing the world all over again. >> reporter: arguably the world's most famous surfer, bethany hamilton, continues to out do herself, this time at the fiji women's pro. >> her ability to avoid the w e wipeo wipeouts. >> she's a super 450uhuman. >> the 26-year-old mom advanced to the semifinals where she

eventually faced third. tweeting beyond stoked to finish third thin wild card, loved competing and looking forward to more adventures. >> i haven't had a good heat in a while, so feels really good. >> she was a top amateur surfer at 13 when a tiger shark took off her right arm. she was back in the water within a month. she spoke with abc's budroe about the experience. >> reporter: tell us about the day you decided to go back into the water. >> i kind of struggled on my first couple waves and didn't get up and then i got up on my third wave and road it all the way to the beach. >> from ket competing in the amazin