>> a small man who used his talents such as they were to become not just a symbol of the loss of innocence or of naivete but an enduring lesson in how not to be a human being. >> that's all for this edition of "dateline." i'm natalie morales. thanks for watching. i'm craig melvin. >> and i'm natalie morales. >> and this is "dateline." >> he said, quote, the bastard shot me. >> he was once a kgb agent but turned into a vocal critic of russia. when he was poisoned in london, it made headlines around the world. >> it's polonium. >> a lethal toxin in a cup of tea. >> it's almost a tiny little dirty bomb. >> it's nuclear terrorism. >> why was he killed?

to unravel the mystery we follow the tale of a dark conspiracy. are you frightened for your life? >> we'll meet and confront the prime suspect. >> did you put the polonium in the tea? >> and now is the danger coming closer? >> with two men waiting in the bushes, one man said shoot him. >> an attack on the expert helping us with this story. >> people say, oh, it's never going to happen here. i know it can happen here because it happened to my husband. >> hello and welcome to "dateline." former russian agent alexander litvinenko was a vocal critic of the russian government. but in his world access to information could make you a very rich man or a dead one. his murder set off an international investigation to discover who wanted him silenced. here's richard engel with "spy games."

>> a former russian agent, poisoned. a multimillionaire found dead in his bathroom. an investigative reporter executed in front of her home. their lives had been interconnected. but what about their deaths? random acts or as some suspect part of an international murder conspiracy that stretches across two continents and several world capitals? we'll investigate who wanted them dead and why. the case will take us from moscow to rome to london, into a world of spies and spy-catchers of corruption and those who dare to expose it. a world in which murder happens often. was there a hit list in mind? >> i'm sure there was.

>> reporter: but our story begins closer to home. on a late winter evening, paul joyal, an intelligence analyst, was driving to his house just outside washington, d.c. it was quiet and dark. >> i got out of my car. there were two men waiting in the bushes. they jumped me. one man i fought with, and we ended up on the ground in a tussle. and this one man said to someone else i didn't see, "shoot him." so i covered my heart with my arms, i turned to the side. and a shot went through me. >> reporter: one shot? >> one shot, and then i heard the click. >> reporter: another click? >> right. and nothing happened. >> reporter: so you're shot once. >> right. >> reporter: you're rolling to protect yourself. >> right. i hear a chamber to clear it,

gun jammed. at that point in time, the lights went on in my house. >> reporter: joyal's wife, elizabeth, heard the commotion. >> all of a sudden, i hear a shot. and that just flipped me out. i knew it was a gunshot. i knew it was a gunshot and i knew it was close. >> reporter: she opened the door and saw her husband. >> he's wearing a raincoat, a suit, a hat, and he's doubled over, and you can see that he's in pain, and he looks at me an fled. elizabeth got joyal inside and called 911. >> as soon as that 911 call was done, asked my son to lift my legs up because i wanted to make sure that most of, you know, the blood was -- >> reporter: stays in the body. >> stays in the body. >> reporter: so you don't lose consciousness. elizabeth is a registered nurse. her training kicked in.

>> there was no sign of external bleeding at that point, so that kind of freaked me out, too. as a nurse, i know if it's not bleeding on the outside, it's bleeding on the inside. [ siren ] >> reporter: an ambulance arrived and rushed joyal to the hospital. the 9-millimeter bullet had torn through his bladder and intestines. they had to place him in a drug-induced coma to save his life. he was unconscious for a month. local law enforcement initially assumed the shooting was a botched robbery, but elizabeth joyal believed otherwise. >> i didn't want to seem like this crazy conspiracy theory woman, but i knew that it was not a carjacking. there's just no way that it was just some random guy. it had to have been a planned attack. >> reporter: because nothing was stolen, and the assailants had

clearly been lying in wait. which is why, when joyal came stumbling into the house with a bullet wound, he told his wife to call his business partner, a former russian spymaster. >> and warn him i was shot. >> reporter: so if you're warning your russian business partner that you've been shot, you clearly didn't think this was a botched robbery, carjacking? you thought this was related to your work, related to your russian connections? >> well, i don't think there's any doubt. >> someone had tried to kill him, just like the other guy in -- in london. >> reporter: the other guy? a former kgb agent and friend of joyal's killed three months earlier in london. assassinated with a weapon so frightening and exotic investigators almost missed it. a weapon that raised the specter of state-sponsored murder. >> coming up -- we trace the steps of a mysterious attack from bus to bar to deathbed. >> he was going through

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behind it? >> reporter: american intelligence expert paul joyal eventually recovered from his near-fatal shooting. in january 2015, he traveled with us to london to tell us the story of what happened to an important contact of his just a few months before joyal was shot. >> he was a law enforcement officer. >> reporter: he worked for the equivalent of the fbi? >> yeah, i mean -- >> reporter: in anti-corruption? >> anti-corruption was what really he was most interested in. >> reporter: his name was alexander litvinenko, sasha to his friends. but his interest in fighting corruption had made him a lot of enemies, including in his own agency, the kgb, which was renamed the fsb. litvinenko was forced to flee russia with his wife and son and seek asylum in london where he quickly caught the attention of agents of the british intelligence service mi-6. glenmore trenear harvey was a retired and very charming mi-6 analyst who was asked to

befriend litvinenko. the british wanted to find out what he knew about his former colleagues in the russian secret services. was he credible? >> oh, yes, he was. >> reporter: credible enough that mi-6 began paying him a monthly salary, trading information for money was one way for a former russian agent to make a living in his new home in london. then suddenly in 2006 litvinenko, who had always been fit and healthy, got very sick. >> it was just incredibly strong and heavy sickness, just suddenly and not stopping. >> reporter: litvinenko's wife marina watched him waste away in a matter of just days. >> oh, it was awful. his hair started to be -- >> reporter: to fall out?

>> yes. and he started to look like a cancer patient treated by chemotherapy. >> i knew he was going through unspeakable torment. >> finally they found in his blood he might have be poisoned. >> reporter: poisoned. doctors suspected maybe he'd ingested thallium, commonly found in rat poison and treatable with an antidote. >> finally. finally, we know what happened to sasha. and now we all under control and he will be safe. >> reporter: but it wasn't under control. the antidote didn't work. litvinenko didn't get better. he got worse. before long even close friends, like andrei nekrasov, could barely recognize him.

>> at some point i said to myself, why should this be happening to this young, healthy, handsome, athletic man? what's going on? >> he's fighting for his life. >> reporter: a fight litvinenko would lose. >> we're sorry to announce that alexander litvinenko died at university college hospital at 9:21 on the 23rd of november, 2006. >> reporter: but in the days just before his death, litvinenko did something remarkable. he knew he was dying and decided to help scotland yard detectives solve his murder. he gave them a series of deathbed interviews. the transcripts provide a remarkably detailed account of his movements on the day he was poisoned. litvinenko's account starts at 10:00 a.m. when he received a phone call from an italian contact, mario scaramella, who'd just arrived in london and insisted he needed to meet

litvinenko immediately. he said he had urgent news. they agreed to meet that afternoon. at 3:10:00 p.m. litvinenko and scarramella were spotted on a security camera walking west on piccadilly street. they came to this sushi restaurant, itsu, where litvinenko ate lunch. scaramella said he wasn't hungry. litvinenko and scaramella parted ways after lunch. at 3:48 p.m., litvinenko was caught on another security camera talking on his cell phone. litvinenko then walked about a mile to the millennium hotel, which is literally right across the street from the u.s. embassy. it's that modern-looking building over there. this is one of the most secure neighborhoods in all of london. one of the hotel's security cameras recorded litvinenko arriving in the lobby at 3:59 p.m. he was there to meet andrei lugovoi, another former fsb agent, seen here wearing a black leather jacket.

lugovoi had his own security consulting firm. he and litvinenko had been talking about doing some business together in london. the two had met several times over the past year. this time lugovoi brought along a buddy, a man named dmitri kovtun. he's the one in the black turtleneck. it was a quick meeting. litvinenko drank just half a cup of tea then left. around 5:00 p.m. he caught a ride home. that night, he fell ill. and three weeks later, he was dead. so who slipped litvinenko poison that day, putting his murder into motion? litvinenko told scotland yard detectives before he died he didn't know when or who had poisoned him. but he had no doubt that one or more of the men he had met that day, the two russians or the italian, was his killer.

naturally, we wanted to talk to all three. coming up -- we track down the first suspect litvinenko named. are you frightened for your life? >> when "dateline" continues.

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the results from a battery of tests came in too late. but they did come in. it turned out he was killed by something far more lethal than common rat poison. >> it's polonium. >> reporter: polonium 210 to be exact, a rare and deadly radioactive isotope. the news shocked the world, even though most people weren't exactly sure what polonium was. but paul joyal knew what it was and what it could do. that his friend effectively burned to death from radioactivity. >> it's a horrible death. it's a gruesome death. he lived longer than he -- than any man normally would under those circumstances. and he lived just long enough, within 12 hours long enough, for them to finally determine that it was polonium versus something else. >> reporter: why, if he had died 12 hours earlier, would it have made any difference?

>> because they wouldn't have found out. they would have marked the death certificate as death unknown. he would have been put in the ground, and it would have been just a mystery. unknown -- unknown assailants. turn the page, move on. >> it's the key of this murder. polonium 210 was discovered and now we know exactly sasha was killed by polonium 210. >> reporter: it's an almost perfect murder weapon. polonium has no smell, little taste, and without specialized equipment, it's undetectable. the amount that killed litvinenko slipped into something he ate or drank was no larger than a grain of salt. but that's still 1,000 times the lethal dose. and that tiny bit of polonium would have been enormously expensive. >> $8 million to $12 million to be able to get the portion that went into him. >> reporter: but who could get hold of such an expensive and exotic weapon?

and how did they deliver the fatal dose? when detectives went step by step with litvinenko through the day he was poisoned, he named three potential suspects -- the two russians and the italian. the first one we found was the italian. in rome, we're on our way to see mario scaramella, who hopefully can shed some more light on who killed alexander litvinenko and why. scaramella has been a hard man to pin down. first, he wanted to meet us in naples, then new york, then london. he finally agreed on rome, and we're about to find out why he's been so skittish. [ speaking italian ] >> reporter: how to describe scaramella? he's a lawyer, an academic, a security analyst and also someone litvinenko never completely trusted. scaramella, you'll remember, is the contact litvinenko met at the sushi bar on the day he was poisoned. litvinenko thought you poisoned him?

>> yes. >> reporter: you didn't poison him? >> absolutely not. >> reporter: from his perspective, it does make sense. >> uh-huh. no, sure, everything is very strange. >> reporter: scaramella had been working for the italian government and sometimes used litvinenko as a source for investigations into the russian mob and spy rings. so he was giving you names of russian mafia members. >> yes, names, dates. >> reporter: who were connected to the intelligence service? >> exactly. >> reporter: something that was sure to upset both the mobsters and the fsb. scaramella told us that in october 2006, the month before litvinenko was poisoned, he began receiving frightening e-mails. the final message arrived on the very day of his last meeting with litvinenko. and what did that message say? >> look, there are people ready to kill you. >> reporter: the e-mails amounted to a hit list. the next name up -- >> alexander. >> reporter: alexander, as in litvinenko.

scaramella says that's why he met with litvinenko in london, to tell him about the hit list, to warn him. but he says litvinenko didn't buy it. >> he said, mario, don't care about that. >> reporter: he says it's b.s. >> i think it's just a provocation, but please check what's happening. >> reporter: but after what happened to litvinenko, scaramella says he takes the hit list seriously. are you frightened for your life? >> well -- do you have another question? >> reporter: scotland yard questioned scaramella and eventually cleared him. why? because if you're looking for it, polonium is traceable. using specialized equipment, investigators were able to track it in people and in places. >> once polonium 210 had been identified, then across europe, like the slime from a slug all the way across, polonium was popping up everywhere.

>> reporter: but not in scaramella. no polonium in his body or anywhere he'd been. so scotland yard took a hard look at the two russians, lugovoi and kovtun. when detectives retraced their steps, they found polonium contamination everywhere. >> we see the same fingerprints of the polonium in multiple places where they were. >> reporter: business offices, hotels, a hookah bar, a strip club, a soccer stadium. and the millennium hotel's pine bar where they last met litvinenko? that's were investigators hit the jackpot. these 3-d graphics put together by scotland yard show the entire pine bar was contaminated with polonium with extreme hot spots on a table and chair. and the levels found inside this teapot? off the charts. paul joyal wonders how many

people were unwittingly exposed. >> do we know, ultimately, what the final cost of this use of polonium is? someone who was washing dishes in the pine bar or in a hotel, cleaning crew? >> reporter: five months after litvinenko's death, scotland yard issued an arrest warrant for lugovoi. kovtun's would come later. the two responded with a press conference in moscow stating their innocence. [ speaking foreign language ] >> reporter: russia refused to extradite them, so we traveled to moscow to find the men who are wanted in connection with litvinenko's murder. >> coming up -- the stakes get even higher as we confront a top russian official. when "dateline" continues. s. psst! psst! allergies don't have to be scary. spraying flonase daily

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a new "washington post" article alleges governor cuomo ran a hostile environment for decades. the cuomo's office says, "the governor is direct with employees if their work is subpar because the people of new york deserve nothing short of excellence." his office also responding to a new "wall street journal" article regarding a third former aide describing inappropriate workplace treatment. cuomo's office says public displays of affection are "what people in politics do." now back to "dateline." in the dead of winter 2015, we arrived in moscow in an effort to find out not only who killed former russian agent alexander litvinenko but why. this is home to andrei lugovoi and dmitri kovtun, hunted by both scotland yard and interpol, suspected of killing litvinenko.

around the world they were villains in a tale of international intrigue and murder, yet here in russia we found plenty of people who thought if the two did kill litvinenko he probably had it coming. thank you very much for talking to us. in the duma, russia's parliament, the pugnacious leader of the ultra-nationalist party has nothing but disdain for litvinenko. >> translator: who needs this little petty person? he was just a piece of rubbish. >> reporter: vladimir zhirinovsky told us that here in russia litvinenko made plenty of enemies going back years. back in the 1990s, russia was in chaos after the collapse of the soviet union. it was a time when enormous fortunes were created and outrageous crimes committed, sometimes by the very people sent to investigate them. back then, alexander litvinenko was a young fsb agent who claimed to be disturbed by what he saw. litvinenko specialized in

organized crime investigations but became obsessed with what he believed to be corruption within the fsb. crimes committed by the cops. he compiled a dossier, complete with flow charts detailing his allegations and presented it personally to the head of the agency. and the result was? >> opposite. >> reporter: surveillance on your family? >> exactly. >> reporter: an outraged litvinenko now did the unthinkable. he led a nationally televised press conference. a group of agents, several of them in disguise, claiming the fsb had become corrupted by russian mafia money. litvinenko even claimed he'd been ordered to assassinate a prominent billionaire, boris ber zofsky but instead warned him that his life was in danger. >> the essential motivation of this very simple man was his feeling that his country was being betrayed by the

leadership. >> he believed he didn't do anything wrong. he was a good officer. >> reporter: and he didn't think it would get him in trouble? >> he said they will kill me or they will arrest me. >> reporter: he was jailed for nine months. but that billionaire he'd warned, berezovsky, bailed him out and helped litvinenko and his family flee to london. there litvinenko kept up the drumbeat of criticism against the russian government. he even wrote a book accusing the fsb of starting a war in chechnya for political reasons. in response, russia branded litvinenko a traitor. his image used for target practice by russian special forces. this wasn't just symbolism. in march 2006, eight months before litvinenko's murder, the russian parliament passed a law

authorizing the liquidation of enemies of the state anywhere in the world. >> you don't pass that just for the sake of passing it. you have to have somebody in mind. >> reporter: seven months after the law was passed, someone was liquidated. a prominent russian journalist, shot in the head outside her moscow apartment. she was a friend of litvinenko. three weeks later, litvinenko himself was poisoned with polonium 210. duma leader zhirinovsky certainly didn't shed any tears when that happened but laughs off the notion that the russian state was connected in any way. for one simple reason. he thinks russian agents would have done a better job. >> translator: i'm surprised that the uk special services and the uk court accuses russia and lugovoi that with a bag of polonium they came to london and were just throwing it around. >> reporter: it just doesn't make sense to a lot of people that russia didn't kill him. >> translator: for a hundred years, the russian special

services have been using the kind of substances for killing people that you never will be able to recognize. why do we have to go into some kind of bar and put it in someone's tea cup and everyone's laughing at it? i mean, the state cannot be involved in that. >> reporter: litvinenko's friend paul joyal, who believes he was the target of a botched assassination, agrees that in some ways litvinenko's killers were indeed clumsy and careless. but he says that's because they were probably just pawns in a much bigger game. >> do you think that any of them knew what that substance was? do you think that they knew they were handling polonium? >> reporter: why wouldn't they have known what they were handling? >> because you don't want them to know. >> reporter: but they could have done a better job not spreading it all over the place if they knew. >> they also might say no, there's no way i'm going to do that. >> reporter: i don't want to handle that radioactive material? >> i am not going to kill myself in the process. >> reporter: to get closer to the truth about who killed

litvinenko, we had to talk to the suspects themselves, andrei lugovoi and dmitri kovtun. in kovtun's case, it wasn't easy. a few weeks after litvinenko died of polonium poisoning, kovtun was hospitalized and lost all his hair. he hasn't been seen publicly since 2012. that left lugovoi. when we got here, he didn't want to speak with us. but on the second day of our trip he called and said he was ready to talk. >> coming up -- we ask the question the world wants answered. >> did you put polonium in the tea? >> when "dateline" continues. one of the worst things about a cold sore is how it can make you feel. but, when used at the first sign, abreva can get you back to being you in just 2 and a half days. be kinder to yourself and tougher on your cold sores.

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meet andrei lugovoi. one of the men scotland yard believes conspired to poison former russian agent alexander litvinenko. we'd been negotiating an interview for weeks. he agreed, then backed out, then finally sat down with us. what did you think of litvinenko? were you friendly? would you consider yourselves friends? >> translator: i have always said that we have never been friends. he was a very complicated person, slightly crazy i would say. he was given to conspiracy theories, to blowing things up out of all proportion. >> reporter: he and litvinenko both used to work for the fsb. both had served time in jail.

it was a bond between them. lugovoi had done very well in business after that and opened a security consulting firm. he says he and litvinenko met several times in london to discuss doing business there together including that now infamous meeting in the pine bar where scotland yard says litvinenko was poisoned. lugovoi says the meeting was no big deal. so what do you remember about sitting there at the table? >> translator: i remember that we talked with litvinenko about nothing in particular. and now for eight years, i am under suspicion. >> reporter: you're under suspicion because the investigation says there was polonium in that teapot. did you put any polonium in the tea? >> translator: of course not. i was tested for polonium, and i tested positive. did i put polonium into myself? am i an idiot? am i crazy?

>> reporter: but scotland yard's detectives don't believe lugovoi's denials. in fact, they think he tried to kill litvinenko more than once. that's because they found polonium on the table in a conference room where he and litvinenko had met two weeks before the pine bar encounter. was anything spilled on the table? >> translator: richard, you are asking questions. i remember some things. i don't remember other things. i cannot answer these questions because these can be used against me in the court, which is done frequently. >> reporter: as for his last meeting with litvinenko at the pine bar, lugovoi says there's no way he brought polonium on that trip because his wife and children were with him. >> translator: a person's weakest spot is his family. and i'm a rational man. even if i had taken part in an operation, even if i had known what was in the container, would i take my family along? i'm a rational man. i couldn't do it.

>> reporter: not only did he continue to maintain his innocence, he offered his own theory about who poisoned the tea. could someone have put something in there without you noticing? >> translator: no. why don't you think the polonium may have been put there into the cup after our meeting the next day or by a guy from mi-6? he brings the polonium and pours it into the cup. that's agatha christie stuff. >> reporter: mi-6 is british intelligence. lugovoi says perhaps the brits killed litvinenko to embarrass russia. retired mi-6 analyst glenmore trenear-harvey says that's nonsense if for no other reason because mi-6 would never use such an expensive weapon to kill anyone. >> if the british wanted to kill him, then he would have fallen out of a hotel window. he would have been placed in front of a car. we'd have spent $12 million in a slightly more cost-effective fashion. >> reporter: you would have made it look like an accident? >> indeed.

things are done less expensively, more cost effectively. old-fashioned bullets in bodies work rather effectively and quite cheaply. >> reporter: why not just shoot him? >> i didn't say they would have done. they could possibly. we -- >> could possibly have done -- >> we -- we don't do that sort of thing. >> reporter: also remember, litvinenko was working for mi-6 and it was lugovoi and his partner dmitri kovtun who left a radioactive trail all over london especially at the pine bar. lugovoi is hardly hiding here in russia. he did our interview in one of the restaurants that he owns. he's a member of parliament. and he's even become something of a pop culture icon hosting his own tv show. the program, appropriately enough, is called "traitors." it names and shames individuals who are supposedly enemies of the russian state. lugovoi's high profile here is just one reason that many people

who suspect him of murder don't think he acted on his own. another reason? all of the polonium 210 in russia is under the control of the state. >> it's impossible to use a state-controlled substance like this without the knowledge of the very top of the country. >> reporter: because you're unleashing a radioactive substance? it's almost -- it's a tiny, little dirty bomb. >> it's nuclear terrorism. >> of all his enemies, lit vin enko may have infuriated one more than any other. coming up -- >> i said this is a very dangerous thing to do because you're personalizing this. >> when "dateline" continues. cs you could take your ulcerative colitis treatment in a different direction. talk to your doctor about xeljanz, a pill, not an injection or infusion, for adults with moderate to severe ulcerative colitis when a certain medicine did not help enough. xeljanz is the first and only fda-approved pill for moderate to severe uc.

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gotta respect his determinatio. it's easy and affordable to get started. get self protection for $10 a month. >> reporter: while in london we had a hastily arranged meeting with another man who's convinced his life is in danger. akhmed zakayev is a wanted man in russia, a rebel leader from the breakaway chechen republic, and a close friend of the former kgb agent alexander litvinenko, who he says gave him an important piece of advice -- never trust old friends. >> he said, someone will come from your past. but you shouldn't trust him because he will be your killer. >> reporter: sasha told you that? >> sasha told me. >> reporter: which may be what

happened to litvinenko. after all, andrei lugovoi was a person from his past. but as we've seen, there were a number of people in litvinenko's past who may have wanted him dead. the fsb colleagues he denounced. the russian mobsters he was investigating. perhaps someone who thought he was a traitor for working with british intelligence. for years now litvinenko's widow, marina, has been asking how big was the conspiracy? who was behind it? how high did it go? dangerous questions, as she knows better than anyone. >> you think you play chess, but they play russian roulette. >> reporter: those who were closest to litvinenko believe the kill order may have come from the very top because litvinenko picked a fight with the wrong person from his past. none other than russian president vladimir putin. >> sasha was on a mission. he was trying to prove that putin is as corrupt as anybody in post-communist russia.

>> reporter: the mission may have started years before when litvinenko made that flow chart of corruption in the fsb. the head of the agency at the time was putin. after litvinenko fled to london, and putin became president of russia, litvinenko attacked him relentlessly and by name. >> i and others said that this is a very dangerous thing to do because you're -- you're personalizing this. >> reporter: you told him that? >> yes. >> reporter: but marina and others believe the ultimate motive may not have been personal at all, rather, it was all about money. we learned that in 2005 and 2006 litvinenko made multiple visits to spain helping prosecutors take down a major organized crime ring. one that litvinenko publicly claimed had financial ties to president putin. putin's office has never responded to that allegation. anne applebaum, a pulitzer prize

winning author and expert on russia. >> i think anything that litvinenko was doing that came close to the source of putin's personal wealth would have been by far the most dangerous things that he could do. >> reporter: in addition to a possible motive there was also the means. paul joyal says the fact that polonium was used to kill litvinenko leaves little doubt as to who authorized the murder. so does that mean it had to be putin? it could have been someone else with access to -- >> come on, come on, you're not going to engage in an act of nuclear terrorism in downtown london without the knowledge of the office of the president. >> today we begin the open hearings in the inquiry into the death of alexander litvinenko. >> reporter: in january 2015, a public inquiry opened in london. it's a victory for marina, who, along with her attorneys, fought an eight-year legal battle to make it happen. on the opening day, her attorney

argued the evidence leads to one disturbing conclusion, which litvinenko himself reached before he died. >> mr. litvinenko came to the awful realization that he had been the victim of a political assassination by agents of the russian state. >> reporter: an expert witness testified the polonium that killed litvinenko could only have come from russia. president putin's spokesman declined our request for an interview. and in march 2015 putin gave lugovoy a medal, the order of merit to the fatherland second class, for his work in the duma. you think russia will ever come clean and this will be known? >> i believe one day we will know this. it will be very obvious for people to decide. >> reporter: in the years she's been looking for answers, other questions have multiplied, other deaths have been recorded. there was boris berezovsky the

russian oligarch litvinenko said he refused to assassinate. another prominent critic of putin. in 2013, he was found dead in his london home. originally called a suicide, a judge said he couldn't rule out murder. >> the way he killed himself -- >> reporter: he hanged himself with a scarf. >> with a scarf, in the bathroom, and the fact that his bodyguard was not there, it raises questions. >> reporter: in february 2015 another putin opponent, boris nemtsov, was gunned down in the shadow of the kremlin. the victim was about to lead a major rally against putin. it went on without him. five chechen nationals were arrested and put on trial. they have denied involvement in the murders. nemtsov's party colleague vladimir karamutza suspected

putin was behind the assassination. >> people shouldn't be killed for their political activity and because they happen to be disagree with the government. the leader of the russian opposition boris nemtsov was killed, gunned down because he opposed the putin regime. for no other reason. >> reporter: putin's office has denied involvement in nemtsov's killing. less than three months after nemtsov's murder kara-murtza himself became the target of an assassination attempt. in may 2015 kara murtza double became very ill. what was italianly thought to be heart problems turned out to be poison. he recovered but in 2017 he was poisoned again. >> i woke up because my heart was racing. the heartbeat was getting faster and faster and faster p. >> you woke up to this feeling. >> yeah. sxl i don't think there are words to describe this.

to describe how you feel when you're trying to breathe and you cannot. and when you just slowly feel your whole body just giving up. >> this time he barely escaped with his life and spent almost two weeks in a medically induced coma. he has never found out how he was poisoned. >> who do you think was responsible? >> i can only presume that this was done by people with at least with connections to the russian special services. >> reporter: the kremlin has denied any involvement in kara-murtsa's poisoning. since the 2016 u.s. presidential election a number of russian diplomats and operatives have been killed or died under mysterious circumstances around the world. in march 2017 the u.s. senate held hearings on russian involvement in the election. >> the american people need to fully understand the threat that we face and what we must do to protect ourselves in the future.

>> reporter: former fbi agent clint watts was called to testify before the committee. >> follow the trail of dead russians. there's been more dead russians in the past three months that are tied to this investigation who have assets in banks all over the world. they are dropping dead even in western countries. >> reporter: so much of this intrigue and violence may seem very far away. but when nbc news consultant paul joyal was shot just a few miles from the capitol, he and his wife immediately thought it was a hit. a big reason? the timing. >> it's four days after i accused the president of being responsible for the horrible murder of litvinenko on your network. >> reporter: in early 2007 joyal appeared in a "dateline" report on the litvinenko case. >> did putin order it? did he know it? we can't say that. i would find it hard to believe that this information, whatever it may be, has not filtered its way up to the top.

>> reporter: just four days later he was almost murdered himself. you think they were related? >> i don't think there's any doubt. >> people out in the general public say, oh, that's in russia. it's never going to happen here. but i know that it could happen here, too. i know that it can happen here because it happened to my husband. >> reporter: there's no proof the joyals are right, but paul's assailants have never been caught. and elizabeth joyal admits at first she was angry when he agreed to be interviewed again for this program. >> i said, what are you thinking? why do you want to bring notice once again? but then when the man in russia was shot, i had a kind of an epiphany. wait a minute. someone needs to talk about this. someone needs to say this is not right. >> reporter: can i ask you an obvious question? why are you still doing this? why are you talking to me now, against -- >> against the advice and counsel of my family?

well, it may be foolish, but i think it's the right thing to do. ♪♪ i'm craig melvin. >> and i'm natalie morales. >> and this is "dateline." she can lie to you, make love to you, kill you, all in the same week. and not even cry at the funeral. >> she was living that dream california lifestyle. you talk about "housewives of orange county." she could have been on the show. she wrapped him around her finger. just like she wraps so many men around her finger. >> she had it all, waterfront home, fancy cars, millionaire boyfriend. quite the life. until -- >> the shots were in sets of two. he saw his attacker.