Three months before he died, the actor Michael K. Williams spent all day at a block party in the Brownsville neighborhood of Brooklyn. In some ways it had the vibe of any block party — a D.J. making people move, kids riding bikes in the street, smoke billowing out of an oil-drum grill. But this wasn’t just another summer day in Brownsville. Mr. Williams and a group of community activists had persuaded seven of the politicians hoping to be New York’s next mayor to show up, granting them a forum to explain why they deserved the support of a Black community that was used to being ignored.One by one, the candidates took turns sitting at a folding table in the middle of the block and fielded tough questions from a panel of young people who lived there. Some of those young people belonged to a gang. Many had lost friends and family members to gun violence, and few had faith in the government’s ability to protect them. Mr. Williams sat at the table, too, listening intently.When Eric Adams arrived, wearing a tight orange T-shirt with the slogan “We Can End Gun Violence,” Mr. Williams expressed concern over his use of the term “law and order” at a recent debate. He chose his words with care, the thumb and forefinger of his right hand pressed together in concentration.“Do you think putting more police on the streets is the way to deal with the violence in our community right now?” Mr. Williams asked.Mr. Adams assured him that he didn’t. “We don’t need an overproliferation of cops,” Mr. Adams said. “People commit crimes,” he added, because “a lack of resources came from the city.”Mr. Williams had an intimate understanding of the kind of violence that results from a lack of resources. Before the world knew him as Omar, the gay stickup artist with a strict moral code from the TV series “The Wire,” he was just a kid from the Vanderveer Estates, a complex of 59 buildings spanning 30 acres of East Flatbush, a largely Caribbean neighborhood deep in Brooklyn. In his memoir, “Scenes From My Life,” which will be published this month, he recalls “The Veer” as a vibrant place where block parties had “the air of family cookouts,” but also as a setting of deprivation and pain. During the so-called crack epidemic, police officers called a local intersection “the front page” because of all the murders that drew reporters to those corners. When Mr. Williams was a teenager, he watched a friend die of a bullet wound right in front of him.Mr. Williams at an event at the Howard Houses in Brownsville in October 2020. Toward the end of his life, he devoted himself to making Brooklyn’s Black communities safer.Sue KwonToward the end of his life, Mr. Williams devoted himself to making Brooklyn’s Black communities safer. He pursued this mission, in part, by helping build a model for organizing that he hoped would eventually inspire a national movement. Through this initiative, called We Build the Block, he and the other organizers held “block activations” throughout Brooklyn, culminating in the mayoral summit in Brownsville. Teenage activists would engage their neighbors in conversations about the political process and register them to vote. The group deliberately chose blocks that the police regarded as gang strongholds, while persuading the police, remarkably, to stay out of the way. “It was a way to say we can take care of our own,” Mr. Williams wrote in his memoir. None of these events, as he noted, were ever disrupted by violence.Last summer, We Build the Block took on an ambitious new challenge. With the help of a Black police captain who was interested in unconventional approaches to crime reduction, they began planning to pay a group of young people touched by gang violence to take part in “healing circles” — weekly conversations led by a therapist. In August, one of Mr. Williams’s collaborators, Dana Rachlin, a white woman in her 30s from Staten Island, texted Mr. Williams that one of their requests for funding was out “in the universe.” Mr. Williams replied, “Damn right it is!”That was the last time she ever heard from him. One week later, on Sept. 6, Mr. Williams was found dead of a heroin and fentanyl overdose in his apartment in Williamsburg. He was 54.Dana Rachlin, who helped found We Build the Block with Mr. Williams.Stephanie Mei-Ling for The New York TimesThe healing circles began the next month. At the first session, a facilitator used singing bowls in an attempt to get the kids to meditate. It didn’t go well. As the kids horsed around and mocked the activity, Ms. Rachlin thought about Mr. Williams. If he’d been there, she thought, the kids would have followed his lead. Lying on a yoga mat, she began to cry. And then she thought about one of the reasons Mr. Williams had been so good at connecting with people: his sensitivity to the pain of others. These boys, she knew, had lost friends too.Mr. Williams’s interest in community organizing can be traced to his mother. He describes her in the memoir as an energetic, caring woman who taught Sunday school, opened a day-care center in their building, and cultivated a network of relationships with community leaders. He loved and admired her. He also feared her. After his father left, when he was 11, his mother tried to protect him from the violence that surrounded them by forbidding him from fighting, a rule that she enforced, as he pointed out, by inflicting violence on him herself. Frustrated by his defiance, she would sometimes tell him that he was unworthy of God’s love.Remembering Michael K. WilliamsThe actor, who starred in the pioneering HBO series “The Wire,” was found dead on Sept. 6, 2021, in his home in Brooklyn. He was 54. Obituary: Williams brought a hard-edge charisma to his portrayal of Omar Little in David Simon’s five-season epic. Tributes: Following news of his death, co-stars, musicians and authors shared their thoughts on the beloved actor. Best TV Performances: Throughout his career, Williams explored provocative intersections of race, crime, sexuality and masculinity. A Legacy Interrupted: To complete the new season of Williams’s series “Black Market,” the producers enlisted the help of some famous friends.He grew to be sensitive and insecure — “the softest kid,” he writes, “in the projects.” After two older men molested him, he “fell into a dark, empty state.” His willingness to venture back into that state, to conjure up his most painful memories for the sake of an acting role, was the quality that would most clearly define him as an artist. The scar across his face, sustained in a razor attack outside a bar on his 25th birthday, seemed to tell of deeper wounds. “We are all broken,” he notes in the book. “And people find it astonishing to see the inside made so visible.”Royal Hyness Allah, one of the young people who helped start the community-organizing campaign, in Brownsville at a We Build the Block event in June 2021.Sue KwonMr. Williams at a graduation ceremony at L&B Spumoni Gardens in Brooklyn.Sue KwonHe was 35 when he landed his most iconic role. A fan of “The Wire” might have assumed that the guy playing Omar shared the show’s political outlook, its outrage at the drug war, but he still knew “close to zero” about politics when the fifth and final season aired. That began to change when an African-American senator from Chicago, running for president that year, declared Omar Little to be his favorite character on his favorite show.Around the same time, Mr. Williams was arrested on drunken-driving charges twice in six months. He had struggled with an addiction to alcohol and cocaine, crack and powder, since he was a teenager. Ordered to do community service, he offered to talk about addiction to high-school kids. What began as an obligation became a passion. While Barack Obama’s praise sparked an interest in the political forces affecting his community, the school visits awakened him to the possibility that he could “redeem” himself by working with young people. But it would still be years before this would become the guiding insight of his life.In 2016, he appeared in “The Night Of,” an HBO drama about the moral rot of New York’s criminal-justice system. Playing a charismatic former boxer confined on Rikers Island, he often thought about his nephew, Dominic Dupont, who was convicted at 19 of second-degree murder. Serving 25 years to life in prison, Mr. Dupont started a mentorship program and, in 2017, received clemency from Gov. Andrew Cuomo.Mr. Williams’s nephew, Dominic Dupont, who was convicted at 19 of second-degree murder. He started a mentorship program and, in 2017, received clemency from Gov. Andrew Cuomo.Stephanie Mei-Ling for The New York Times“The Night Of” told a less redeeming tale, and the performance took Mr. Williams to a dark place. “He was willing to sacrifice himself for some roles,” Mr. Dupont told me. “And those happened to be the characters that people loved the most.” After years of sobriety, Mr. Williams began using drugs on the set, which was an actual prison in upstate New York. It got so bad, his memoir revealed, that the shoot had to be shut down for a day.While promoting the series, Mr. Williams realized he wanted to learn more about the mass incarceration of young people from neighborhoods like his. This led him to make “Raised in the System,” a documentarythat captures the vulnerability and neglect of incarcerated children. Ms. Rachlin, who met him as he was finishing the film, helped him organize a series of screenings for police officers, correction officers, prosecutors and judges. “We wanted the power holders to bring compassion and empathy to the youth before them, their families and communities,” she said.Ms. Rachlin was in some ways an unlikely ally. She had grown up in a conservative Staten Island household. As a teenager, she made campaign calls for George W. Bush. She recalls assuming that people who committed crimes were “bad.” But after college, while working as an advocate for crime victims in the Staten Island courthouse, she found herself, for the first time, spending time around young people who had been arrested and jailed. It was eye-opening. She soon began working with adolescents who had been getting into trouble, eventually starting a nonprofit.As Mr. Williams became an increasingly prominent advocate for criminal-justice reform, Ms. Rachlin continued working closely with him, connecting him with nonprofit groups in the field, teaching him about the inner-workings of government, prepping him for meetings with elected officials. Mr. Williams, for his part, used his fame to attract attention to her work, and served as a personal mentor — “Uncle Mike” — to kids in her organization.Capt. Derby St. Fort with Mr. Williams at a We Build the Block event in Crown Heights in 2020. Captain St. Fort would collaborate with the organization on healing circles.Sue KwonThen, in the summer of 2020, as protests over police violence surged through New York and the rest of the country, Mr. Williams began talking to Ms. Rachlin about how to bolster the role that Black New Yorkers played in shaping the city’s public-safety policies. With the radio host Shani Kulture and five high school students from Brooklyn, they started We Build the Block, the community-organizing campaign.Royal Hyness Allah, one of the young people who helped start the initiative, recalled how down-to-earth Mr. Williams always seemed at their block activations. “He was outside at every event,” he said, “no security, no nothing, talking with the old people and the people rolling dice and smoking weed, getting to know where their head’s at, spreading the word about how to make the community safer.”“He was unique,” Eric Gonzalez, Brooklyn’s reform-minded district attorney, said. “A lot of people with his celebrity, they do social media or they donate money to causes, but he kept it on the ground.”Captain St. Fort felt a deep kinship with Mr. Williams. “With all his success, he didn’t feel deserving,” he said. “I felt the same way at times.”Stephanie Mei-Ling for The New York TimesIn 2019, Ms. Rachlin introduced Mr. Williams to Derby St. Fort, the police captain who would collaborate with them on the healing circles. Captain St. Fort felt a deep kinship with Mr. Williams. “With all his success, he didn’t feel deserving,” he said. “I felt the same way at times.” When he told Mr. Williams about a group of young men who were causing harm in his precinct, Mr. Williams said he could imagine how they felt — unworthy of love, incapable of change. “He looked at the pain of those who caused pain,” Captain St. Fort said. Arresting them wouldn’t change their perspectives. So the three of them developed a strategy that they hoped would.This was how the healing circles came about. Despite skepticism inside the police department, Captain St. Fort fully embraced the idea and even participated in the circles himself. He found it hard to imagine that the kids would ever trust him, but he was open with them, acknowledging that he had made mistakes in his life. Slowly, he said, the teenagers began to open up too. “A lot of times they felt they had done so much harm in their lives that they weren’t deserving of support,” Captain St. Fort said. “We had to challenge that. I told them, ‘You deserve it.’”Two of the participants, Dorian Garrett, 18, and Kareem Holder, 20, now volunteer as community organizers. One recent afternoon, they met with Captain St. Fort and Ms. Rachlin, along with representatives of the Public Advocate’s Office, the NAACP Legal Defense Fund, and other groups in the basement of a public library, where they were leading an effort to plan a back-to-school event for younger kids in their neighborhood. They’d both gotten steady jobs through the program, and neither had been arrested since the sessions began.They’d never met Mr. Williams, but Ms. Rachlin and Captain St. Fort had told them all about the guy with the scar they’d seen on TV — how he made people feel like they mattered, like somebody cared. “That’s something that I definitely want to do,” Mr. Garrett said, “because the stuff that I experienced, I don’t want that for the younger generation.” He wanted those kids to know something. “I’m here, and they are loved.”Mr. Williams at a voter registration in Brooklyn in 2020. “We are all broken,” he wrote in his memoir. “And people find it astonishing to see the inside made so visible.”Sue Kwon More