Transcript for How the Oklahoma City bombing has influenced white supremacists: Part 1
Reporter: The white power movement -- You will not replace us! Reporter: Hidden in the shadows for decades, now re-emerging across the country. The danger now is that so many people feel more comfortable speaking in racist terms, who otherwise used to be under the rocks, in the crevices. Now they're out. Reporter: The actions of these groups, including their most violent fringe, can be traced back to playbooks decades old. A legacy of one of the most influential and dangeroustill haunts these appalachian hollows. To be honest, I have an awful lot of stuff going through my mind that I think about, going up to this property. You know, my dad -- he gave up everything to go out there. And I know he believed in what he was doing. And, you know, he created this compound, but he was so misguided and so deluded. Reporter: Kelvin pierce grew up with a front-row seat to hate. My father was Dr. William Luther pierce. Reporter: William Luther pierce, dead for nearly two decades, is still considered among the nation's most dangerous white supremacists. Many people call us racists, hate mongers. It's about hatred. It's about racism. It's about exclusion. Reporter: One of the first and most famous leaders of the nation's modern white power movement, William pierce was the founder of a far-reaching extremist group, the national alliance. What worries me a lot is the unchecked tide of nonwhite immigration into this country, both legal and illegal. That is what is really breeding disaster. Reporter: Especially active in the '80s and '90s, the national alliance attempted to bring white power propaganda to the masses. This whole movement was about becoming an enemy of the nation, to unseat the federal government, create civil disturbance, and for many people, it's imagined as a way to provoke race war. Basically, to create a white-only homeland. Reporter: Kelvin pierce is in West Virginia, trying to find the old compound that today is still owned by his father's group. I guess I'm probably a little nervous. It's been almost 20 years since I've been there. I've only been there twice. Reporter: Kelvin's father moved to this secretive compound after rising to white supremacist infamy with his novel. Jimmy: "The turner diaries." It's sort of like a bible for the whole movement. It truly is the most violent exercise of what it would take to create an all-white state, nationan writings turned from William pierce's fictional fantasies to real-life tragedy. The whole front of the federal building is gone, all floors to the roof. I'm Peter Jennings at ABC news headquarters in New York. A major explosion in Oklahoma City in a federal building in the center of Oklahoma, about 9:00 local time in Oklahoma -- We've got a lot of children hurt. We need to get in. Reporter: The Oklahoma City bombing claimed the lives of 168 people, including 19 children, and injured hundreds more. As the investigation into the bombing unfolded, the evidence pointed to a very diary at. We could also give you a bit of a hint now as to where the government owe peers to be focusing its investigation. On some of the what are called right-wing white supremacist groups in various parts of the country. Early on in the investigation, there was a piece of the vehicle used in the attack that was quickly uncovered. And they found a vin number. And they were able to trace that back to Timothy Mcveigh. Reporter: Timothy Mcveigh, a 26-year-old man from upstate new York, arrested within hourers of the bombing. Here he comes. Mr. Mcvay! All the discussions were about, why did he do this? Where did he come from? Who is he connected to? Reporter: Inside Mcvay's yellow Mercury van, investigators discovered a sealed envelope that would contain evidence crucial. The anti-government novel "The turner diaries" -- Reporter: Written by William pierce, long held sacred by the white power movement. He usually had a copy wherever he went. He oftentimes had extra copies that he would give to others. Reporter: Authorities never did tie the national alliance to the Oklahoma City bombing, pinning the devastating crime on Mcvay and a few accomplices, including Terry Nichols and Michael fortier. But it became clear Mcvay's ties to white power groups ran deep. They're brothers in arms, that is, they're survivalists, quasi-survivalists, and I can get along with them real well. Whether it was a Nazi, whether it was a white supremacist, whether it was a survivalist, whether it was a militia man, he would have fully embraced their views. It took me awhile to accept that Tim had, in fact, joined the Ku klux Klan. He tried to downplay that. But other comments showed that hostile attitude towards people of color. Reporter: Timothy Mcvay was convicted of the Oklahoma City bombing and executed on June 11th, 2001. It is absolutely sad and tragic may most of us knew very little about the development of the movement in which Timothy Mcvay was embedded. We didn't know how far the tentacles reached. Reporter: It turns out there were warnings that something like this could happen. Six months prior to the bombing in Oklahoma City, the southern poverty law center sent a letter to then-attorney general Janet Reno, and we talked about what we were seeing in terms of the threat from the anti-government movement. We saw more and more of this kind of thing happening on the ground. It's time for the government to take a new look at white supremacist groups, hate groups, militias? Is this going to trigger any kind of crackdown? Let me say that we need to finish this investigation. At the time, I don't really think that there was an understanding of how much of a threat we were dealing with within our own country. Reporter: To the white power movement, violence is a means to an end. Something that Kelvin pierce says was ingrained in his upbringing. I remember fantasizing about going into Washington, D.C. And standing on a street corner, holding a machine gun, and mowing down black people with that machine gun. Reporter: But as a college student at Virginia tech, Kelvin began asking questions and distancing himself from his infamous father. I learned that I did not need to attach myself and my self-worth to all of the fearful and hateful thoughts that were continually runni through my mind, and that I had a different choice. Reporter: At the same time, across the country -- Maximum violence upon them. Reporter: The white power movement, far from the spotlight of authorities, continues to add followers. When you talk to experts, the '90s was kind of a heyday with Timothy Mcveigh and the militias of the day. That was kind of the last time we seemed to, as a country, really grapple with this right-wing extremism. This is a difficult moment for America. Today we've had a national tragedy. 9/11 happened. And our focus shifted overseas. We took our eyes off the ball in terms of the threat from domestic terrorism. End immigration! Charlottesville happened in August 2017. For many of us, it was a huge wake-up moment. Blood and soil! Racist Nazis literally showed up. These people felt very comfortable being out in the open, in the light of day, to push their hatred. A short time ago we were dispatched to active gunfire at the tree of life synagogue in squirrel hill. Reporter: 2018 and 2019 saw a historic increase in white power violence. Breaking news, we are learning more about the synagogue massacre. Reporter: With the deadliest attacks against both jewish and Latino communities in American history taking place. 11 people murdered at the tree of life synagogue in Pittsburgh. Shoppers at Walmart running for their lives as gunshots rang out. Reporter: And 23 gunned down at an El Paso Walmart. After El Paso happened, there was a lot of appropriate activity at the white house where they were examining what policy changes might need to occur. Reporter: With the white house now on board, Newmann and her team revived earlier plans to reprioritize white power threats, now the number one threat. Along the way she says she received an unusual request by the white house. They directed me that, your prevention plan is good, we want to support it. We can't talk about it in the framing of domestic terrorism, we need to talk about this in terms like violence prevention. The message was clear that we couldn't talk about domestic terrorism at the white house. Reporter: In a statement to ABC news responding to these claims, the white house said, contrary to these meritless allegations, there is nothing more important to this president than protecting the U.S. From all threats, both foreign and domestic, and he has repeatedly taken strong actions to keep America safe. An ABC news investigation found that since Donald Trump emerged as a presidential candidate in 2015, at least 20 people charged with hate-fueled assaults or threats cited trump specifically in connection to their actions. We couldn't find any such cases tied to either president bush or president Obama. When we return, a son confronts his father's deadly legacy. Can I help you? My name is Kelvin pierce. How are you doing? I was Dr. Pierce's son. Yes. Is there any way we could get permission to walk around? And what experts believe the country must realize before another attack on American soil.
This transcript has been automatically generated and may not be 100% accurate.