Transcript for A deeper look into the life of Martin Luther King Jr., 50 years after his death
Reporter: It is the sound of a dream not yet forgotten. I have a dam today. Reporter: Martin Luther king jr.'s icon I have a dream speech still seared in the minds of so many. I have a dream that one day this nation will rise up, live out the true meaning of its creed. Reporter: But perhaps even more than a dreamer, he is remembered tod as a visionary, a tribute for the civil rights leader who was assassinated in memphi Tennessee, at just 39 years old. The reverend martiluther king, the leader of the nonviolent civil rights movement in the United States was assassinated in Memphis tonight. Reporter: 50 years later, the same men who witnessed Dr. King's assassination, remembered him at the site where he was killed, the Lorine motel, now the civil rights museum. One of many tributes hel across the nation. The country honoring the legacy he left behind. That's not just keep talking about Dr. King. Let's start trying to live and fulfill the mission he was on. And as my brother would say, realize the dream. Reporter: While king's work has long been celebrated publicly, the intimate moments of his private, personal life rarely seen until now. ??? Happy birthday ??? Reporter: Tho candid moments captured in the new HBO documentary "King in the wilderness We know that you really don't need much. Reporter: Dr. Clayton worked with king and was a clo friend of the family. Here she is celebrating what would ultimately be his last birthday. When you go to jail, here are shoestring potatoes. Many of us feel we know a lot about martin Luther Ng, but you knew him personally. People are sprised to know is that he was just the funniest person ever. People can't imagine him laughing and telling jokes and having a good time base when you saw him in public, he was talkingerious issues, so I wasn't clowning around. Martin Luther king Jr. Was a human being. And he was imperfect. He was conflicted, but his love was unchallengeable. Reporter: The new film traces the last three years of his life, a time that those closest to him say his smile began to fade. The most difficult time in his life was the 18 months before his assassination. Ways in Kenya to preach nonviolence. Reporter: It took a turn afr his beyond Vietnam speech April 1967, one year before his death. T greatest purveyor O violce in the world today. My own government. Reporte his stance against the Vietnam war sparked backlash even among his followers. He knew that his enemies often WOU not support his cause, but he expected his friends to support him. He really died, I think, wh that broken heart feeling. Reporter: Those tough moments front and center in the documentary all leading up to the painful details of his death. Clayton was with king's widow Coretta Scott kin they he died. She said to his staff, I don't wantnybody to talk to my children. I want to do that myself. So I don't want them knowing anything except what I tell them. And so they had them sent to their rooms and Waid for her. And so she asked me to stay with her. She said now I got to talk to the boys. Will you go in the room with me? I said yes. She took me in the room, and she had almost a death grip on I H arm as she told the boys. She said later it was the hardest thing for her. Reporte the film's director, Peter conhart, said he thought it was important to have witnesses to history like ayton tell those difficult stories. People kind of think I have a dream marked the culmination of his career when, in fact, there were three very controversial years tt followed. Reporter: A perspective that would shine new light on how we viewed Dr. King. I think king to Thi generation is either a granite statue or a cardboard figure, and we wanted to bring him to life. Reporter: Do you think that his message 50 years ago still resonates as much today, 2018? Ver the years, his belief in nonviolence was kind of yawned over. 'S the patient, nonviolent approach that's radical. I mean, even just a week ago with king's granddaughter standing up a saying, enough is enough. It's being practiced and it's working. I'm granddauger of martin Luther king and Coretta Scott Ng. Reporter: 50 years later king's granddaughter following in his footsteps, reciting his famous words in the March for our LIV in Washington. Electrifying the crowd. I have a dream thatnough is enou. And that this could be a gun-free world, period. Having children participate was one of his secret weapons for change. In fact, when Yolanda stood up D said enough is enough. She then burst into this big smilef a little girl. It was king's smile. I saw king's face come right through her face. Reporter: Today in membrane of Dr. King, his granddaughter joined other boy and girls of every race just as her grandfather had envisioned. These teens marching 50 miles from Mississippi to Memphis. His symbolizes how we've moved forward. Reporter: Three generations walking side by side. These guys will be able T say 50 years from now they were part of making history around Dr. Ks legacy. Rorter: Today's king's youngest daughters speakingut against shootings and police profiling as she told my colleague Steve osunsami. America has to find a way to value life. When you look at the black men being gunnedown by law enforcement officers, it's very troubling. Reporter: At one pnt even melting a handgun at today's rally. I think people need to know that we can't just pause in this moment and honor a great man. We really have to consir embracing his mission. Reporter: They say he ovided us a blueprint, a vision and a dream, all outlined in their father's most recited speech, words that the king family say still mean jt as much today. I have a dream. That my four little children will one day liven a nation where they Wil not be judged by the color O their skin but by theontent of their character. I have a dream. Our thanks to Lindy Davis for her reporting night. The HBO documentary film "King in the lderness" is currently available on all HBO platforms.
This transcript has been automatically generated and may not be 100% accurate.