the last to know. prescription for cheating. they read our x-rays but a cnn investigation reveals a disturbing question over the certification of many radiologists. isn't it cheating? revealing investigations. fascinating characters. stories with impact. this is cnn presents, with your host tonight, brooke baldwin and dr. sanjay gupta. we begin with a rare look inside anonymous. >> they're the motley group of activists who answer to no one, drawn together by love of internet mischief. >> now they're evolving into this movement of social change, a real driving force behind the wall street occupiers. they're hated by security and hunted by the fbi. >> who are these people and why are they taking to the streets? to get some answers, amber lyon stepped into the shadows. >> reporter: it's a dark and disturbing vision. a world where riot police attack with impunity. >> what happened? what happened? >> he got hit. >> he got shot! >> reporter: where democracy is corrupted by greed and dissent is crushed. that's how anonymous sees america and they say that's why they're fighting back. >> we are legion. we do not forgive. we do not forget. >> reporter: it's a movement that defies description. leaderless, faceless, anarchic. >> this is our space! >> reporter: a loose collective born on the internet, it has no official members and no hierarchy, but within the group some individual anons have greater standing, earned by their skills as hackers, video makers -- >> to see it with my own eyes and record it myself. >> reporter: -- and increasingly street level activists. troy, not his real name, is one of them. >> this is what happens when the people have had enough. this is what happens when greed goes unchecked. >> reporter: troy said he was drawn to occupy wall street after watching his mother struggle with medical debts. he himself is working two jobs to make ends meet, despite having a college degree. >> you lose track of day, lose track of time but it worth it. it's all worth it. >> reporter: we met him at the occupy wall street camp at zuccotti park. >> there's no specific person i talk to. it's move like a hive, an idea is brought up and whoever agrees with it, if the overwhelming majority of people agree with it, then we go with it. >> reporter: so we're following troy and he's been out here policing, kind of making sure that all of these protesters are getting along with the community and not causing any problems. >> we're handling internal affairs as far as damage control within the community, making sure that everybody is respecting the local small businesses around here. >> reporter: but he's not just watching over the protests. he's also watching the police. part of the evolution of anonymous from hackers to activists. anonymous was born a decade ago in one of the weirdest and darkest corners of the internet, an anything goes board called 4chan. the users post anonymously and the name stuck. the group adopted a distinct identity and its own symbolism, a mask taken from the movie "v for vendetta," a retelling of the story of the english rebel guy fox and his plot to blow up the house of lords in 1605. instead of gun powder, anonymous uses the internet. anonymous attacks its targets by flooding and crashing corporate and government web sites or digging up and publicizing highly embarrassing information. it's called trolling. they troll targets out of genuine outrage but also just for fun. >> lulz -- it's a bastardization of laugh out loud. >> reporter: new york university professor gabriela has been watching anonymous for years. >> it's a term that sort of denotes the sort of pleasure, humor, laughter, everything from something which is quite playful, harmless to engaging in a full-fledged trolling attack that humiliates. >> reporter: anonymous's campaigns, known as operations or ops, can be dramatic. in late 2010 a distributed denial of service attack took down the web site of paypal. after the company cut off support for the online whistleblower site wikileaks. >> they continue to withhold funds from wiki leaks. >> reporter: 16 anons were arrested by the fbi, charged with conspiring to intentionally damage paypal's computers. >> this is a message from anonymous. >> reporter: this summer, anonymous attacked the san francisco area's public transportation system b.a.r.t. b.a.r.t. had cut cell service within the transit system as a way of disrupting anti-police brutality protests. anonymous's reaction was devastating and vicious. >> we will not issue anymore warnings. >> reporter: onbart included the release of a naked photo of a senior bart employee. >> sometimes it makes you laugh, sometimes it makes you cringe, sometimes it makes you laugh and cringe at the same time. all of a sudden you're like, oh my gosh, there is this dagger that's being thrown. >> reporter: and a naked photo? >> yes. >> reporter: do you feel there is a fear out there of what they could possibly find or leak about a certain individual? >> absolutely. i mean, that's what makes them who they are is that they are kind of bad boys and rude boys to some degree. there is a dual sort of fascination and horror that goes on at the same time. >> be aware. be vij rant. >> reporter: anonymous was evolving, using its power to shock and disrupt to effect social change. during the arab spring, the collective emerged as a full fledged activist group. taking up the cause of tunisians fighting against a repressive regime, literally saving lives. >> the tunisian government has made itself an enemy of anonymous. >> they did everything from take down government web sites, they wrote scripts to stop the fishing of passwords, brought massive media attention to tunisia. >> reporter: and last fall anonymous broke cover here at home, stepping out from behind their secure computer screens for a new cause, occupy wall street. >> there is a revolution brewing. >> reporter: suddenly the symbols of anonymous were everywhere, in flags, masks, banners. >> we are the 99%! >> reporter: when we return, pepper spray and anonymous strikes back. how are they getting the personal information of these officers? 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[oinking] [hissing] [ding] announcer: cook foods to the right temperature using a food thermometer. 3,000 americans will die from food poisoning this year. check your steps at foodsafety.gov. will be giving away passafree copies of the alcoholism & addiction cure. to get yours, go to ssagesmalibubook.com. the shadowy internet group known as anonymous has grown far beyond its hacker roots and is emerging as a forceful public relations weapon for the occupy wall street movement. amber lyon takes you inside anonymous. >> reporter: anonymous likens itself to the air force of the occupy movement. >> everyone, everywhere will occupy their capitals and other public spaces. >> reporter: anonymous has an array of people on the streets, we're talking medics in san francisco, tech support in washington, d.c. and here in new york guys like troy. troy, not his real name, is part of an army of citizen journalists documenting the movement and the police by broadcasting live video over streaming sites. when they see evidence of what they believe is police misbehavior, anonymous strikes back, releasing personal information about specific officers. >> hopefully he'll think twice before he pulls out his baton against somebody who is holding a sign saying we just want peace. >> reporter: how are they getting cell phone numbers and personal information of these officers or bankers? >> i'd rather not say. >> reporter: in september an nypd officer was filmed pepper spraying two protesters. anonymous took action. one of the most active subgroups within anonymous is called the cabin crew. their specialty is doxing. it's shorthand for combing the internet for all the information you can find about a target and then releasing it publicly. >> cabin crew have noticed injustices being committed by the new york police. >> reporter: cabin crew compiled bologna's name, his home address, past legal actions, even the names of his family members and put it all online. after a police investigation and public pressure, bologna was placed on leave and reassigned to staten island. what do you think that did to the nypd when they saw this officer's information get posted online? >> i think they would see it as a form of vigilanteism. they're pushing the boundaries of the law. but i think their actions reveal the ways in which either private security companies or police are also acting outside the boundaries of the law. >> reporter: its biggest coup in the propaganda wars was this. an anon group by the name operationleaks posts the clip on youtube. the next day the clip tops 100,000 views. three days later one and a half million. the casually spraying cop had it all. it was outrageous, ridiculous, lulzy and effective. >> pepper spraying student protesters. >> reporter: the incident was picked up by mainstream media and replayed over and over again. anonymous wants to frame the narrative of the occupy movement as a contest between peaceful protesters and a militarized police state. >> oh, my gosh. >> reporter: reality, though, isn't quite so clear cut. at occupy oakland, some protesters attacked the police with rocks and bottles. others erupted in a fury after the city tore down their encampment. >> some people are trying to tear down this fence and head into the main area but others are trying to keep them quiet and calm so that the police don't have to get reinvolved. >> we need some more help over here. >> we're non-violent. >> you're willing to fight us but not the police? you're doing their job. >> reporter: the anonymous pr machine focused solely on instances where the cops got out of line. and they have plenty of ammunition. >> what happened, what happened? >> he got hit. >> he got shot! >> reporter: during one night of chaos, police apparently fired a projectile directly at a former marine named scott olson, who was protesting against the crackdown peacefully. anonymous went into overdrive, scanning the video for police badge numbers and names, offering a reward for anyone who could identify the officer responsible. the case is still under investigation. the department of homeland security has put out several alerts to law enforcement and corporate security focused mainly on the group's hacking activities, and the fbi has made more than a dozen arrests. >> we are living in a police state. >> reporter: but there's no indication that has cramped anonymous's style. their latest op? >> merry christmas and a happy new year to all on planet earth. >> reporter: on christmas day members crashed the web site of a security research company, hacking its client list along with their credit card numbers in order to steal $1 million for donations to charity. >> we are anonymous. expect us. our correspondent amber lyon joins here in studio. a little frightening, a little scary. >> especially for law enforcement in many aspects. >> what if they get it wrong? what if they put up personal information that is inaccurate? do they have any accountability? >> there's very little accountability because of the way it's organized, anyone can claim to be anonymous. there's a lot of extreme outliers. law enforcement is intimidated by anonymous. we tried to get an interview with anyone federally or locally and they refused to send an officer forward to the chopping block because they feared he could become a target of anonymous. >> coming up, is it possible schools could be making your child sick? my investigation finds it's a hidden problem all around the country and it's one the kids can't avoid. you're giving me the silent treatment? ummm, yeah. jen, this is like the eighth time you've called... no, it's fine, my family has free unlimited mobile-to-any-mobile minutes. i can call all i want. i don't think you understand how the silent treatment works. hello? 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[ male announcer ] the new capital one cash rewards card. the card for people who want 50% more cash. what's in your wallet? sorry i'll clean this up. shouldn't have made it rain. the parents say public school 51 in the bronx, they thought they had won the jackpot. their children won the lottery to get coveted spots in one of new york's best public elementary schools, but they found out the school had a problem. it wasn't the teachers or the test scores or even the other kids. the problem was the building. it's toxic. that's right. it wasn't safe for the children. and p.s. 51 isn't alone. it's part of my ongoing reporting on toxic towns, our investigation found all over the country children are going to schools that can make them sick. our first stop was p.s. 51. >> i need your lunch bag. >> okay. >> marisol is helping her son brandon get ready for the first day of school. brandon seems excited but marisol seems nervous. this is more than just a case of first day jitters. ♪ i cannot wait to get to school ♪ >> reporter: in august just weeks before school started, marisol saw this emergency meeting notice taped to brandon's school, p.s. 51 in the bronx. that night she joined an auditorium packed with worried parents. chancellor dennis wolcott opened the meeting with a dramatic statement. >> first i want to start out by apologizing to all of you. >> reporter: he followed the apology with disturbing news. >> we decided to do environmental reviews. your school came with a result that we were not satisfied with, with an elevated level of tce. >> tce is a carcinogen, prolonged exposure can cause parkinson's, cancer, even death. tests at p.s. 51 showed tce levels at a hundred times worse than what's considered safe. >> based on the final confirmation, we thought we needed to shut the building down. >> reporter: parents are upset. >> you are using euphemisms. you're trying to be nice. that was a building that was storing chemicals that were cancer causing agents and because of the vicinity and the children that are involved, you didn't care. >> and you guys, board of ed, first allowed it to be used as a school for our children. i think it's so inappropriate. >> reporter: but the parents were even more upset by the fact that the department of education discovered the contamination in january, yet parents weren't told and their children were kept in class through the end of the year. >> i voiced my displeasure with our folks as far as the timeliness of the notification. from this point on, whenever we get a positive notification around some type of environmental issue, the parent community, the staff and the school community will be notified immediately. >> reporter: i met marisol outside that contaminated school. so the staff, the kids, all the people essentially in this building a good chunk of their days knew nothing about in? >> no. the chancellor said he was sorry. >> reporter: how worried are you? >> very worried. this is the school right here. >> reporter: marisol says even brandon, who is normally upbeat, is worried. you like this new building? >> mm-hmm. >> reporter: you know why you're in the new building? >> yeah. >> reporter: why? >> because it closed down because of tce, a chemical. >> what do you know about tce? >> it's a cancer causing chemical. >> reporter: we wanted to ask chancellor wolcott about why he didn't tell parents about it until months after he knew about it. after repeated requests, his office declined to speak with cnn. >> for the sheer callousness and recklessness of the behavior toward kids, this is as bad as i've ever seen. >> reporter: lawyer sean collins has won a number of tce contamination suits for communities around the country. >> the people who ran this school and their environmental consultants knew for at least six months that there were dangerous levels, in some cases off-the-charts levels of chemicals in the air that these kids were breathing and yet they let those kids go there day in and day out every day for the rest of a semester. unconscionable. >> reporter: collins said the building should never have been a school. >> it's an old industrial site, not a place to have kids going to school. >> reporter: new york city records show p.s. 51 did house a car garage and a lamp factory. tce, once used to degrease metal, could have been leftover waste. many schools around the country are built on old industry sites according to lenny segal, who digs up the past of toxic schools. >> we don't consider contamination before we decide where to put the school, and particularly in new york city where they have so many schools on leased properties, most of which are former industrial sites or at least many of which, i don't know the exact number, they had a policy of not looking for problems. >> reporter: segal believes ground and water testing should be mandatory. he also says p.s. 51 was probably always problematic. just weeks before brandon and the other p.s. 51 kids started school, parents were hit with more unsettling news. tests revealed slightly elevated level of a common but toxic dry cleaning chemical, pce. parents showed up at another meeting in october to confront the chancellor. >> i first have to say dennis wolcott, how dare you! >> reporter: the chancellor dismissed the results at the new school as insignificant. >> there was an open container and so once that was corrected, the levels came back down. it was fine. >> reporter: but parents like marisol no longer trust the school system. what are you going to do? what's the plan? >> i'm just going to watch him consistently. any little thing that he gets is going to be an alarm for me. he's 8 years old and it's scary and i have to see what's going to happen with him. i pray that nothing's going to come of this but you just don't know. >> reporter: when he come back -- >> about a third of our schools have some kind of problem that causes respiratory problem