Transcript for George Floyd’s death reopens old wounds of similar police-involved incidents
Reporter: With every passing second, George Floyd's life was slipping away. Ah, ah. Reporter: This ten-minute video is difficult to watch but impossible to ignore. Now crucial testimony bearing witness to an ugly reality. Mama. Mama. Get up! Reporter: Face down on the pavement, crying out for his mother, a police officer's knee to his neck. My stomach hurts. My neck hurts. Everything hurts. Ah. There's water or something. Please, please. Ah, I can't breathe, officer. Reporter: A bystander's cell phone recording Floyd's pleas for breath, capturing those precious words for those excruciating minutes. His nose is bleeding. Reporter: This, the second video of a black man dying to emerge in less than a month. Seeing ahmaud arbery killed by citizens while he's jogging. Watching George Floyd be killed by police, all these incidents back to back. Please don't tell me he's gone. Reporter: From Eric Garner to ahmaud arbery, all part of a seemingly endless stream of footage, revealing the violence so many have experienced, challenging police versions of events, some like Orlando Castile in Florida. He was trying to get out his id. Reporter: Offering a narrative of lives cut short igniting calls for social justice. It's wrong, period. Reporter: Floyd's sister Bridget left in disbelief. I don't understand how someone could possibly let an individual go out like that. A state of emergency in black America. The pandemic that existed long before the coronavirus of racism and discrimination that often leads to the unjustifiable and unnecessary killings of people of color in America. Reporter: Outrage from the graphic video of Floyd dying, spilling onto America's streets. From Houston to Chicago. What do we want! Justice! When do we want it? Now! Reporter: And Minneapolis. Where police in riot gear fired what appeared to be tear gas. This, the latest salvo in the country's reckoning on race. Video is an indispensable part of our struggle to get justice in these cases. Without video, we're not talking about ahmaud arbery. We're not talking about George Floyd. Video is our evidence. Video is our proof. Reporter: Remembered by his friends as a loving father and gentle giant. The world going to remember his name. The world going to remember George Floyd. He wasn't supposed to go out like that. Reporter: Floyd, seen here in a 1992 high school football game scoring a touchdown. For Steven Jackson, the loss of his 46-year-old friend is like losing family. Floyd was my brother, doing what he was supposed to do, y'all kill might brother, man. Growing up in the streets. Reporter: Both Jackson and Floyd were star athletes growing up in Texas. We same talent, the same dreams, we grew up in the same type of areas. I just had more opportunity. Reporter: In adulthood, Floyd ran into trouble. In 2007 he was charged with armed robbery. In 2009, sentenced to five years in prison as part of a plea deal. He'd been through a lot of stuff in his life. He had gone to Minnesota to start a new start. Reporter: When you hear him saying he can't breathe repeatedly, how does that hit you? Makes me so angry, because Floyd's one of the strongest people you know. And to hear that scream and that cry for help in his voice, and he cried out for help and -- it's just wrong, man. It's just wrong. Reporter: Alvin was Floyd's roommate. He recalled a time when Floyd told him about being pulled over for driving with an expired license plate. He said I know they get intimidated by my size, so I stepped back a little bit, saying I'm sorry, I wasn't aware of it and the officer gave him a pass. Reporter: And tonight new video seeming to contradict a police account showing the moments before Floyd was restrained by officers. In the video, police approach Floyd's SUV, hand cuff him and take him to the sidewalk. Then Floyd and the officers walk across the street where that fateful video was recorded. The fundamental issue hire is when he's in a hand cuff, at that time they're using excessive force. Reporter: Police say they were responding to a forgery in process. The video starkly differs from a statement issued Monday night by Minneapolis police, saying Floyd had resisted officers and appeared to be suffering medical distress. Usually deadly force is allowed when that individual is resisting or commit order about to commit a violent felony. For George Floyd, he did neither. Reporter: Minutes later, the fire department was called for a patient with trauma to his mouth. The city today releasing the disgraced officers' names. Shovin is the officer with his knee on Floyd. The mayor calling for him to be charged with a crime. If you had done it or I had done it, we would be behind bars right now. And I look forward to asking the jury just to watch and stopwatch for nine minutes, in silence, and think about not being able to have sustained breath for those nine minutes. How is that not murder? Reporter: It was just six years ago when those words -- I can't breathe, I can't breathe. Reporter: A plea from garner on the streets of New York turned into a rallying cry. But for Glen Carr, they're the last words she'll hear from her son. When you see this scene of George Floyd going through what he went through, what popped into your mind? It just brought back horrible memories of the day that I found out that my son Eric was murdered. I can feel their pain. I know what they're going through. Reporter: You said you can't bring yourself to watch the video of George Floyd. No, I can't. Reporter: And yet, it's the video that has opened a lot of other people's eyes. Yes. 11 times he's repeated "I can't breathe", but the disconcerned officers, they paid no attention to his cries. They continue murdering him. And this is just like the sentiments of this young man who was killed the other day. The man was trying to only breathe. Reporter: Now, an outspoken activist to bring justice for so many who aren't being heard. I don't want any other mother to suffer like I've suffered. Reporter: A makeshift memorial now growing on the street where journal Floyd took his last breath. For those who loved Floyd the most like his sister Bridget, the loss numbing and the fear haunting, that it could one day take her own sons. You never what could happen when they walk out the door. They need to know how to defend theirself, how to stand up for thrself, how to talk for theirself, because if I don't teach that to them, this world, this cold, cold world will take
This transcript has been automatically generated and may not be 100% accurate.