>> bill: and he can really get after it. he has improved. >> jim: averages 3 a game. he has 10. hicks. on the floor. three by adebayo. >> grant: and they swarm on defense. way to move your feet and not foul. >> bill: same play. >> grant: he stayed on his left hand and he went right. >> jim: that's kentucky's biggest lead of the game. >> bill: back screen. can pick that. >> jim: rattles out. >> bill: this is where you h good selection by kentucky and dig deep defensively for the heels. >> jim: step-up jumper. humphries again. >> bill: this kid will get player of the game. >> jim: a career-high for humphries. you got something. own it and smell great with new axe you, a unique masculine fragrance. everyone, shut up! and... listen! (chittering) do you hear that? you always... have been... my... best... friend... forever. to friendship. (cheering) ( ♪ ) latte for candice. ♪ you're a barista guy! ♪ ♪ but you're also a guy who loves buzzer beaters and dunks! ♪ ♪ and you don't wanna miss a thing! ♪ with directv from at&t, you can stream all your live ncaa march madness games on your devices. ♪ and we'll take some of these croissants! ♪ get directv for $25 a month when you have the new at&t unlimited plus plan. ♪♪"let me tell you 'bouts" the birds the beesn ♪ ♪ ♪ and the flowers and the trees♪ ♪ and the moon up above ♪ and a thing called love. ♪ ♪ let me tell you 'bout the stars in the sk♪, ♪ a girl and a guy ♪ ♪ and the way they could kiss on a night like this ♪ life's as big as you make it. introducing the all-new seven seater volkswagen atlas ♪ and a thing called love. >> jim: tonight on cbs, "60 minutes, "ncis: los angeles" and "madam secretary." >> bill: and this is usually for monk or willis, not for isaac humphrey. you keep playing like this, you will be sir isaac. >> grant: and then a one-on-one situation. fantastic minutes. too good a player to stay quiet for long. isaac humphries, stepping up. >> jim: north carolina led by 6 with 10 minutes to go in the game. it's been a 17-6 run by the cats. >> bill: carolina has to reach inside of their offense. be solid. trying to >> grant: adebayo on berry after the switch. >> jim: 5 to shoot. runner. pinson. >> grant: looks like carolina is going to a zone, to stop the momentum of zone. >> bill: this is where fox is good. they come out of this on the drive. >> jim: humphries tries it again. misses. meeks, career-high 17th rebound. >> grant: humphries, he checked there to see if he could make it. >> bill: wide open, pull the string. if carolina runs the zone, they have to know where monk is. >> jim: they drive it. first on briscoe. half. >> bill: have to load up in there. >> jim: shot clock running down. floater. back to the rim. >> grant: great defense. better offense always wins out. >> bill: briscoe is a good driver. and always looms large on any penetration. there he is. >> jim: taken to the basket. hits the floor. >> grant: and let me tell you -- we're used to seeing point guards go up and block shots what a fantastic play. these guys are leaving it all on the court. kentucky up one. play-by-play: a minute and twenty seconds to go... kansas and kentucky... down to the wire... what?!? no! the whole street is out! over there! lights! look! c'mon! that block has power! ♪ ♪ play-by-play: kansas with a huge play, and just two seconds left.. excuse me, are you aware of what's happening right now? we're facing 20 billion security events every day. ddos campaigns, ransomware, malware attacks... actually, we just handled all the priority threats. you did that? we did that. really. we analyzed millions of articles and reports. we can identify threats 50% faster. you can do that? we can do that. then do that. can we do that? we can do that. link to keep their global campus connected. and why a pro football team chose us to deliver fiber-enabled broadband to more than 65,000 fans. and why a leading car brand counts on us to keep their dealer network streamlined and nimble. businesses count on communication, and communication counts on centurylink. >> jim: your summary. north carolina headed to the line to shoot two. big foul by fox, his third. here's the capital one cup impact performance. >> grant: it's been humphries stepping up and making plays. the the field, so the bench has stepped up. second half, all that man right there, humphries. >> bill: he played so well, i knighted him. >> jim: knots it at 64-64. >> bill: charming young guy, isn't he? >> jim: yes. they've turned to him for attitude. the last six to north carolina it take the lead at 65-64. knocked out. that shot. >> bill: puts pressure on the point guard. >> jim: the heels came from five down late against arkansas to score the last 12 points in that game. they were down five a few minutes ago to kentucky. follow-up. no basket. foul on hawkins. >> bill: couldn't get control. pushing and got maye underneath the glass. >> grant: north carolina will send three guys to the boards. >> bill: it's been a tradition since dean smith. >> grant: i have nightmares. >> jim: seventh team foul on kentucky, so maye, who strokes it with great authority from the outside, has been making 1-1. it's tournament time and he's turned into a new animal. don't miss country music's party of the year, country music awards next sunday after "60 minutes." it's tournament time and he's cree creating all kinds of new numbers for his resume. kentucky down three. >> bill: drive concept with the ball screen. >> jim: to tie it. rebound out to maye. eight unanswered for north carolina. >> bill: have to protect the basketball inside. have to be breaking. >> grant: defensive ly boxing ot after the shot. >> jim: berry off the deck. nice hesitation. this has to be feeling familiar to last week. time-out, kentucky. if you are a tarheels' fan, it's just like a sunday ago. >> bill: the team in blue, little guy that struggled early, able to deliver the sweet kiss in memphis. ♪ you have a side that is retired ♪ ♪ playing tag and gettin' tired. ♪ ♪ you have a side that saves for their tuition. ♪ ♪ but right now it looks like bedtime is the mission. ♪ ♪ a side that owns your own store. ♪ ♪ looks like you need to expand some more. ♪ ♪ they help protect and grow your many sides. ♪ ♪ nationwide is on your side. >> jim: 1:45 left. look who is already set. south carolina headed to the promised land for the first time, same for gonzaga. and oregon hasn't been on this stage since 1939 when they won the championship 78 years ago tomorrow. but who will be the fourth and final team? and the winner to take on the ducks in the semifinals next saturday in phoenix? >> bill: monk without the basketball, dribble exchange. >> jim: stripped away in the hands of berry. >> bill: not a good look either. was for briscoe. want to run your stuff under 10. >> grant: will go one-on-one with berry here. >> bill: that extension, gamer. >> grant: and briscoe, tough physical defender. you're right, pushoff trying to create some separation from berry. acting skills. taking kentucky out of rhythm here in the last 3 minutes. >> jim: no good. come up with the basketball in the last going. kentucky scoreless for the last 4 minutes. and fox commits that foul. >> bill: that's four. >> jim: yep. will be a 1-1. >> grant: the man that didn't play last game, doing a great job on the defensive end and there hitting the free throw. >> jim: there's your reset. each team with a couple of time-outs. arrow, carolina. 12 unanswered. another late 12-0 run. >> bill: briscoe, he will not jump out, because he's not a great shooter, but he has leadership qualities and to drive strong and find the nylon. (mic thuds) uh, sorry. it's unlimited without compromising reliability, on the largest, most advanced 4g lte network in america. (thud) uh... sorry, last thing. it's just $45 per line. forty. five. (cheering and applause) and that is all the microphones that i have. (vo) switch to unlimited on verizon now and get our best android smartphones for as low as $15 a month. >> jim: tonight on cbs, "60 minutes," "ncis: los angeles, 0 i . >> bill: a couple of years ago kentucky didn't go big on the ball and something strange happened. >> grant: and you don't have to r try to create a turnover. don't foul in the backcourt. >> bill: they're big on the ball. >> grant: watch the home run pass here. >> grant: and meeks, the division-maker. can see over the traffic. >> jim: in trouble. interesting that he took it out. >> bill: not quite the great decision-maker. only advantage was seeing over the top. guys have to screen and step to the ball. >> grant: and you have it have a mental count in your head and know the time-out situation. untimely turnover by the tarheels. >> jim: looked like a quick draw instead. monk, he will take it. >> bill: oh, wow, what a shot. down to one. >> jim: and takes it in. 25 seconds. good defense. and adebayo lost it. on the floor. and is it a jump ball? or possession arrow -- don't you love that effort? >> bill: the effort is sensational and malik monk, big time shot, gathered himself and knocked it in. and, of course, your guy jackson, you love this play. what a great setup. look at the footwork here, j.j.! >> jim: carolina possession. time-out, tarheels. did not feel like a cloud... that driverless car? i have seen it all. intel's driving...the future! traffic lights, street lamps. business runs on the cloud... and the cloud runs on intel. ♪ i wonder what the other 2% runs on...(car horn) >> jim: remember, if there's a full here, as you expect, it will be a 1-1 for north carolina, leading by three. here's the tie-up. pinson got his hands in there to knock it out of the hands of adebayo. >> grant: love it when three big guys on the floor are diving for the ball. >> bill: they don't want him to get fouled. could be part of the reasoning. >>im last time. now he does. >> bill: perfect trap. >> grant: didn't need to foul right there. >> jim: going to send a first team all-american to the line for a 1-1. >> bill: we've seen kids grow up. last year, final four, we spent time with jackson, very quiet, understated. >> jim: different guy this year. >> bill: isn't it great? that's the benefit -- i know there's the reason that kids go and have to leave before the growth. but so impressive for this kid. >> jim: huge shot right here. monk to tie it. looks up. driving in. berry for the win. with .3 seconds to go. >> bill: how about that kid the way he has played and the chain of events. off the screen right now. and malik monk, big time shot. two people hanging all over him, knocking it down and tying up the game. maye has raised his level of play. >> grant: you think maye likes playing in memphis? >> jim: let's talk about what kentucky has to do here. by the way, they confirmed here it's a two. you can tell he's inside the arc. .3 seconds. can only tip it. >> grant: exactly. defensively if i'm carolina, i have everybody back in the paint. might have two on the ball. has to be careful running the baseline, trying to draw a charge. >> bill: it has to be long for a tip. anything in the backcourt, you're dead. >> grant: i agree. >> jim: 25 years ago tuesday theres with a guy that we know, bill, that threw a pass in a regional final at the end of the game. >> grant: and i don't want all the kentucky listeners to be upset. i didn't bring it up. >> bill: who might that be? [laughter] >> jim: i just know it was a good one. >> bill: how about these kids? talk about toughness. coming back. you mentioned the arkansas game and grant talking about how he's played here in memphis. >> jim: this north carolina team just driven, since last summer, to get back to the final four. redemption, that's the term. williams talked about how it gave the team fuel to work harder in the off-season and it carried over all this season and they will put bradley on the inbounds. willis to throw it in here for kentucky. heaves it down the floor. it was never touched. >> bill: checking to see if it was touched. >> grant: if it's not, it's back here on the baseline. >> jim: adebayo saying it touched his >> bill: there were not two people involved, so the rule is -- >> jim: saw jenkins, who hit the championship shot last year in houston. pinson, lood like he at the last minute backed off of it. and i think he did. >> grant: yeah. smart play. >> bill: interesting because the rule is, if two people are involved in it, they good to the monitor. this is such an important situation. >> jim: it will go back to where willis inbounded it. carolina will inbound and give me a scenario for kentucky. >> bill: there's nothing really they can do. just have to inbound it. >> grant: unless there's an offensive foul by north carolina. i cannot imagine anything happening. roll the ball on the floor and it's over. >> bill: or throw it at somebody. and don't push off or do anything silly. a >> jim: it's over. north carolina will be looking for redemption in the desert. >> bill: unbelievable performance. we talked earlier about toughness, about responding, down a few points. this is one of those pleasure to be aboard. >> grant: it was. i thought north carolina went to their zone with 6 minutes left, and took kentucky out. and they were able to close out the game. >> jim: when they went to that, to your point, they were down 64-59. they came out of the time-out and that's when they made the change defensively and went on a 12-0 run, just as they did last week when theye which had a 5-point lead. >> bill: and then it was a time-out and went back to man. so some strategy and some great play. and on to phoenix, huh? >> jim: on to phoenix. yesterday belonged to the west. we have two teams in the final four from the west for the first time ever. today belonged to the carolinas. p>> bill: and roy has a way wit ducks. we saw that today. [laughter] >> jim: south carolina-gonzaga, that will be the first game up, 6:09 eastern time. and then oregon at north carolina, second national semifinal. >> bill: what a pleasure. >> grant: we were treated this afternoon. >> bill: you look at this bracket and there are all kinds of interesting scenarios. you could have the all-west final, gonzor somebody suggested -- if that happens, they should move it to seattle or something. or you can have a north carolina-south carolina championship matchup. tracy, over to you. >> that's a lot, jim, i have the whole team over here. everybody say luke maye, how about the way he's come off in the last two games? >> i'm the guy that wanted him to as a walk-on. how dumb am i? big time plays. made a heck of a drive. i didn't want to call a time-out and fouled luke. congratulate kentucky. they paid three threes in the last minute, but my guys are doggone tough, too. >> what can you say about their toughness and how they showed that? >> i told them it was the same as arkansas. we were down 5 and played our butts off and that's what they did today. >> luke, what your mind? monk ties it up. what were you thinking? >> i was late on the switch and i got out there late and then i shot it like i do every day in practice. >> you are going back to the final four. back to you. >> jim: luke maye, pride of huntersville, north carolina. on their way to phoenix. "60 minutes" leads off the lineup tonight. for bill, tracy, grant, so long from memphis. carolina takes the south regional championship. we'll see you in the final four. closed captioning provided by cbs sports division. ♪ (cover of chainsmokers 'don't l♪ me down') ♪ ♪ the issues we care about can weigh on us. visit state farm's neighborhoodofgood.com to volunteer in your community. it's not about where you were born. it's not about your gender. or the color of your skin. or whether you're rich, poor, or in the middle. no matter what you play. if you have the skill and drive to succeed in school and in sports, we'll provide the opportunity. captioning funded by cbs and ford. we go further, so you can. being watched by the f.b.i. for years, but it didn't stop him from carrying out the first terrorist attack claimed by isis on u.s. soil. it happened in garland, texas. simpson and another terrorist opened fire at a conference center. incredibly, an f.b.i. undercover agent was on the scene. lies on the left and right fed by fraudulent software that scam our social media accounts. click on a fake news site, and publishers like jestin coler make money. >> people in general are quick to believe anything that is... not anything, but, well, yeah, basically anything that's put in front of them in a format that is news-ish. >> alfonsi: until a couple summers ago, the ancient game of chess was still mostly a mystery for the folks of rural franklin county, mississippi. >> what's this called? >> alfonsi: so imagine everyone's surprise when a tall stranger arrived from memphis to bring chess to the country. >> i was like, what? why would somebody come down here? >> alfonsi: less than two years later, a chess boom is under way in the unlikeliest of places. >> people said that country kids couldn't learn chess. >> alfonsi: and? >> we showed 'em different. >> we proved 'em wrong. >> i'm steve kroft. >> e-mail lesley stahl. >> i'm bill whitaker. >> i'm anderson cooper. >> i'm sharyn alfonsi. >> i'm scott pelley. those stories tonight on "60 minutes." see me. see me to know that psoriasis is just something that i have. i'm not contagious. see me to know that... ...i won't stop until i find what works. discover cosentyx, a different kind of medicine for moderate to severe plaque psoriasis. proven to help the majority of people find clear or almost clear skin. 8 out of 10 people saw 75% skin clearance at 3 months. while the majority saw 90% clearance. do not use if you are allergic to cosentyx. before starting, you should be tested for tuberculosis. an increased risk of infections and lowered ability to fight them may occur... ...tell your doctor if you have an infection or symptoms... ...such as fever, sweats, chills, muscle aches or cough. if you have inflammatory bowel disease, tell your doctor if symptoms develop or worsen. serious allergic reactions may occur. see me. see me. see me. on my way. find clear skin... and a clearer path forward. for a different kind of medicine, ask your dermatologist about cosentyx. where plans start at onlycricket $30/month. and more 4g lte coverage than t-mobile or sprint. plus, when you switch now you can get a brand new smartphone for free. cricket wireless. something to smile about. attack in london by a man who had been known to british law enforcement is just the latest reminder of how difficult it is to prevent an attack before it takes place. here in the u.s. in just the past three years more than 100 people have been arrested for isis-related crimes. the f.b.i. devotes significa potential terrorists and sometimes spends years tracking them. the terror attack in garland texas two years ago was the first claimed by isis on us soil. it's mostly been forgotten because the two terrorists were killed by local cops before they managed to murder anyone. in looking into what happened in garland, we were surprised to discover just how close the fbi was to one of the terrorists. not only had the fbi been monitoring him for years, there was an undercover agent right behind him when the first shots were fired. the target of the attack was an event taking place in this conference center on may 3, 2015. a self-described free speech advocate named pamela geller was holding a provocative contest, offering a cash-prize for the best drawing of the prophet muhammad, whose depiction is considered sacrilege by some muslims. security outside was heavy. there were dozens of police, a swat team, and snipers. more than 100 people were gathered inside and the event was ending when two terrorists drove up to a checkpoint manned by a garland police officer and a school security guard. this grainy image shows both law enforcement personnel standing next to an unmarked police car seconds before the attack. bruce joiner, the security guard, was unarmed. >> joiner: it's like they pull up, stop, and the doors open. >> cooper: do you remember seeing the weapon? >> joiner: oh, yeah. definitely saw their weapon. and that's when i locked onto his face cause he's got this smile. >> cooper: he was literally smiling? >> joiner: yeah, like, "i got you. i got you." ( gunshots ) >> cooper: the two terrorists opened fire with automatic rifles. joiner dove for cover, but was shot in the leg. officer greg stevens, returned fire with his handgun. police nearby ran toward the scene. >> and right here ( bleep ) just started shooting at this convention! >> cooper: when this video was rerd terrorists had been mortally wounded by officer stevens, and were laying on the ground next to their car. >> they still shooting, man! >> cooper: a swat team shot them both in the head. >> joiner: because they kept moving and they weren't sure there were explosives involved they had to shoot them. >> cooper: how quick did all of this happen? >> joiner: oh, it's a matter of seconds. i would say 20, 30 seconds. it's very quick. >> cooper: the next day as the fbi picked through the crime scene, the evidence showed garland police had prevented a massacre. the terrorists brought six guns, hundreds of rounds of ammunition, bulletproof and tactical vests, and xeroxed copies of the black flag of isis. they were identified as 31-year- old elton simpson and 34-year- old nadir soofi. just hours before the attack they had sent this tweet pledging allegiance to isis. but simpson was already well- known to the f.b.i. he grew up in the suburbs of chicago, and movo arizona in middle school. he briefly played college basketball before dropping out and converting to islam when he was 20. according to leaders of the phoenix mosque he attended, simpson was well-liked and soft spoken. >> shami: he was always asking questions, attending lectures. >> cooper: usama shami is president of the islamic community center of phoenix. people here thought so much of the young muslim convert, who took the name "ibrahim," that he was included in the mosque's promotional video in 2007. >> when you come together and you pray five times a day with the brothers and you're reminded about the hereafter. >> cooper: but at the time of this interview, simpson had already become interested in radical islam, and the phoenix fbi, which was investigating one his friends, hired an informant, a sudanese refugee named dabla deng, to check simpson out. >> cooper: there are informants inside the mosque? >> shami: yeah. i mean the whole case with elton that he was befriending elton and taping his conversations. >> cooper: dabla deng spent three years pretending to be simpson's friend, and was paid $132,000 by the fbi. he taped more than 1,500 hours of their conversations and finally recorded him talking about traveling overseas to wage jihad. simpson lied to the fbi about it and got three years probation. >> shami: when he found out that this guy was spying on him, and taping him and then finding out that the government was doing that, i think something clicked in him. and the mosque we couldn't do anything. because we don't know what he did. >> cooper: he felt that the mosque had abandoned him? >> shami: yes. and he felt that a lot of people had abandoned him. and that's why he stopped coming to the mosque. >> cooper: he moved into this phoenix apartment complex with nadir soofi, who he knew from the mosque. soofi had just had a bitter owned was going out of business. it was here in this apartment that simpson and soofi began closely following the rise of isis, reaching out to their supporters online, and acquiring weapons for a terrorist attack. >> hughes: simpson and soofi knew what they were getting into and i think they likely knew they were going to die. >> cooper: seamus hughes tracks the online activities of isis sympathizers in the u.s. he served at the national counter terrorism center, and is currently deputy director of george washington university's" program on extremism," where he also trains fbi agents on how to identify american jihadis. why is the garland attack so significant? >> hughes: the garland attack is essentially the first opening salvo when it comes to attacks on the homeland. >> cooper: attacks in the united states? >> hughes: attacks in the united states. these low-level attacks by ones and twos of people who are drawn to the ideology and decide to act. you got to make sense of it all. so what you do is you bring it all together and put it on a board and say who's connected to who. hughes maps out isis' online tentacles into the united states. >> hughes: so you have the two attackers, soofi and simpson. they're also talking to mohammed miski, who's an isis recruiter in somalia. >> cooper: this is somebody in somalia who they're talking to online... >> hughes: uh-huh. yep. through an encrypted app, surespot. they're also talking to junaid hussein. >> cooper: and he's in raqqa? >> hughes: he's in raqqa. >> cooper: raqqa is isis's stronghold in syria. hughes calls junaid hussain an" isis rock star," a british citizen, who communicated online with english-speaking recruits worldwide. he was killed in a u.s. drone strike a year and a half ago." miski," an american living in somalia, tweeted this link about the "draw muhammad contest," in garland texas, and direct- messaged elton simpson urging him to attack it. >> hughes: the most interesting part about this is we're in a hybrid time, right. before we used to be worried about these network attacks, think of 9/11 with the hijackers training for years and then coming over here. and then, we had lone actor attacks, individuals who were kind of drawn to this and decided to act. now, we're in this weird moment in between, where you have a number of individuals in raqqa, reaching out to americans in ohio, new york, and other places and saying "so here's the knife you should use. here's the address of the local u.s. military officer and do what you can." >> cooper: do you think elton simpson would have launched this attack if it wasn't for people in isis overseas who were online whispering in his ear? >> hughes: i think the folks whispering in his ear was a big part of it. >> cooper: the f.b.i. closed the case on elton simpson in 2014, only to re-open it several weeks before the attack because of statements he made on social media. >> hughes: it speaks to a larger problem the f.b.i. has, which is you have an individual who pops into your radar in 2006, but doesn't commit an attack until 2015. so do you want the fbi to watch this individual for nine years? >> cooper: after the attack, phoenix fbi agents became convinced the two men hadn't acted alone, and began investigating elton simpson's friends. they arrested this man abdul malik abdul kareem, a 43-year- old convert to islam who grew up in philadelphia, and accused him of funding the attack, as well as training and encouraging simpson and soofi. witnesses at abdul-kareem's trial testified the three men watched isis execution videos together and discussed attacking a military base or the 2015 super bowl in glendale, arizona. abdul-kareem denied taking part in any discussions about a terror attack and says he rejected his friend's growing radicalization. he was found guilty on multiple counts and sentenced to thirty years in prison. but his attorney dan maynard continued to investigate, and uncovered new evidence the fbi was much closer to the garland attack than anyone realized. after the trial, you discovered that the government knew a lot more about the garland attack than they had let on? >> maynard: that's right. yeah. after the trial we found out that they had had an undercover simpson less than three weeks before the attack to him "tear up texas." which to me was an encouragement to simpson. >> cooper: the man he's talking about was a special agent of the fbi, working undercover posing as an islamic radical. the government sent attorney dan maynard 60 pages of declassified encrypted messages between the agent and elton simpson and argued "tear up texas" was not an incitement. but simpson's response was incriminating, referring to the attack against cartoonists at the french magazine charlie hebdo: "bro, you don't have to say that..." he wrote "you know what happened in paris... so that goes without saying. no need to be direct."ñh but it turns out the undercover agent did more than just communicate online with elton simpson. in an affidavit filed in another case the government disclosed that the fbi undercover agent had actually "traveled to garland texas and was present at the event." >> maynard: i was shocked. i mean i was shocked that the government hadn't turned this over. i wanted to know when did he get there, why was he there? >> cooper: and this past november, maynard was given another batch of documents by the government, revealing the biggest surprise of all. the undercover agent was in a car directly behind elton simpson and nadir soofi when they started shooting. this cell-phone photo of school security guard bruce joiner and police officer greg stevens was taken by the undercover agent seconds before the attack. the idea that he's taking photograph of the two people who happen to be attacked ( laughs ) moments before they're attacked. >> maynard: it's stunning. >> cooper: i mean, talk about being in the right or the wrong place at the right or the wrong time. >> maynard: the idea that he's right there 30 seconds before the attack happens is just incredible to me. >> cooper: what would you want to ask the undercover agent? >> maynard: i would love to ask the undercover a the only communications that you had with simpson? did you have more communications with simpson? how is it that you ended up coming to garland, texas? why are you even there? >> cooper: we wanted to ask the f.b.i. those same questions. but the bureau would not agree to an interview. all the f.b.i. would give us was this email statement. it reads: "there was no advance knowledge of a plot to attack the cartoon drawing contest in garland, texas." if you're wondering what happened to the f.b.i.'s undercover agent, he fled the scene but was stopped at gunpoint by garland police. this is video of him in handcuffs, recorded by a local news crew. we've blurred his face to protect his identity. >> maynard: i can't tell you whether the f.b.i. knew the attack was going to occur. i don't like to think that they let it occur. but it is shocking to me that an undercover agent sees fellas jumping out of a car. and he drives on. i find that shocking. stop... >> maynard: he didn't try to stop them. or he didn't do something. i mean, he's an agent, for gosh sakes. >> cooper: if this attack had gone a different way, and lots of people had been killed, would the fact that an undercover fbi agent was on the scene have become essentially a scandal? >> hughes: it would have been a bigger story. i think you would have seen congressional investigations and things like that. lucky for the fbi and for the participants in the event you know, here in texas, you know, everyone's a good shot there. >> cooper: the f.b.i.'s actions around this foiled attack offer a rare glimpse into the complexities faced by those fighting homegrown extremism. today the battle often begins online, where identifying terrorists can be the difference between a massacre, and the one that never occurred in garland, texas. people brag about stuff. people talk big. one of the difficulties for the f.b.i. is trying to figure out who's just talking and who actually may execute an attack. >> hughes: that's the hardest part when you talk about this, right. there's a lot of guys who talk it's very hard to tell when someone crosses that line. and in most of the cases, you see the f.b.i. has some touch point with those individuals beforehand. there had been an assessment, a preliminary investigation or a full investigation. it's just very hard to know when somebody decides to jump. (man vo) it was may, when dad forgot how to brush his teeth. (woman vo) in march, my husband didn't recognize our grandson. (woman 2 vo) that's when moderate alzheimer's made me a caregiver. (avo) if their alzheimer's is getting worse, ask about once-a-day namzaric. namzaric is approved for moderate to severe alzheimer's disease in patients who are taking donepezil. it may improve cognition and overall function, and may slow the worsening of symptoms for a while. namzaric does not change the underlying disease progression. don't take if allergic to memantine, donepezil, piperidine, or any of the ingredients in namzaric. tell the doctor about any conditions; including heart, lung, bladder, kidney or liver problems, seizures, stomach ulcers, or procedures with anesthesia. serious side effects may occur, including muscle problems if given anesthesia; slow heartbeat, fainting, more stomach acid which may lead to ulcers and bleeding; nausea, vomiting, difficulty urinating, seizures, and worsening of lung problems. most common side effects are headache, diarrhea, dizziness, loss of appetite, and bruising. (woman 2 vo) i don't know what tomorrow will bring but i'm doing what i can. (avo) ask about namzaric today. so i trust nature made vitamins. health and life. because they were the first to be verified by usp for quality and purity standards. and because i recommend them as a pharmacist. nature made, the #1 pharmacist recommended vitamin and supplement brand. hi, i'm frank. i take movantik for oic, opioid-induced constipation. had a bad back injury, my doctor prescribed opioids which helped with the chronic pain, but backed me up big-time. tried prunes, laxatives, still constipated... had to talk to my doctor. she said, "how long you been holding this in?" (laughs) that was my movantik moment. my doctor told me that movantik is specifically designed for oic and can help you go more often. don't take movantik if you have a bowel blockage or a history of them. movantik may cause serious side effects, including symptoms of opioid withdrawal, ain and/or diarrhea, and tears in the stomach or intestine. tell your doctor about any side effects and about medicines you take. movantik may interact with them causing side effects. why hold it in? have your movantik moment. talk to your doctor about opioid-induced constipation. if you can't afford your medication, astrazeneca may be able to help. >> pelley: in this last election the nation was assaulted by imposters masquerading as reporters. they poisoned the conversation with lies on the left and on the right. many did it to influence the outcome; others just to make a buck. the president uses the term "fake news" to discredit responsible reporting that he doesn't like, but we're going to show you how con artists insert truly fake news into the national conversation with fraudulent software that scams your social media account. the stories are fake, but the consequences are real. this past december, edgar welch opened fire in a washington d.c. pizzeria. he told police he was there to rescue children forced into prostitution by hillary clinton. the story of secretary clinton's child sex trafficking operation, in a pizzeria, was invented before the election by fraudulent news sites and shared by millions. james alefantis owns the >> alefantis: it started on november 4, 2016, where i started to get strange messages directly into ag and these direct messages were saying all kinds of very strange and bizarre things. >> pelley: like what? >> alefantis: many of the threats, death threats, i think were some of the worst. people saying that they wanted to see my guts cut out and spill on the floor of my restaurant. one person said that they prayed that someone would come and kill everyone inside. and it was terrifying moments. >> pelley: edgar welch fired into the only locked door in the restaurant and found, much to his surprise, no sex slaves. no one was hurt unless you count alefantis, an innocent bystander at a character assassination. >> alefantis: it went from a few people buzzing about something online or inside of chat rooms that we never would have seen before, to suddenly being blasted to millions and millions of people. >> pelley: the police say there is no sex trafficking conspiracy. but millions read about it on dozens of websites, including one called "danger and play," which wrote, "clinton's inner circle includes child traffickers, pedophiles and now members of a sex cult." danger and play is written by michael cernovich, a southern california lawyer who describes himself as "right of center politically" but who has become a magnet for readers with a taste for stories with no basis in fact. >> pelley: these news stories are fakes. >> cernovich: they're definitely not fake. >> pelley: they're lies. >> cernovich: they're not lies at all. 100% true. >> pelley: do you believe that, or do you say that because it's important for marketing your website? >> cernovich: oh, i believe it. i don't say anything that i don't believe. >> pelley: that doesn't seem like a very high bar. >> cernovich: it's a high bar because i'm an attorney, i know how to weigh and measure evidence. here's the story of my life. >> pelley: cernovich streams commentary daily and publishes on social media. he reached twitter users 83 million times last month.