A young Brooklyn man has pleaded guilty to the unprovoked killing of social justice advocate Ryan Carson in a caught-on-video stabbing that took place as Carson and his girlfriend walked down a Brooklyn street on their way home from a wedding. Brian Dowling, 20, pleaded guilty to second-degree murder Wednesday, accepting a plea offer from Brooklyn Supreme Court Judge Danny Chun. His sentencing, where he is expected to get 20 years to life,  is slated for Feb. 19. Dowling, who was 18 at the time of the killing, sobbed as he was led from a Brooklyn NYPD station house in shackles and handcuffs after his October 2023 arrest. Neighbors described him at the time as a nice kid who got along with others in the neighborhood. Brian Dowling is walked from the 81st Precinct in Brooklyn on Oct. 5, 2023. (Barry Williams for New York Daily News) “Like an average, normal teenager,” close family friend Eric Riddick, 58, told The News. “Just like any other teenager, finding his way, coming up as an adult. … He was working in construction. We talked a few weeks ago on the block, and he seemed fine. He was a great kid.” Carson, 32, and his girlfriend were sitting on a bench at a bus stop near Malcolm X Blvd. near Lafayette Ave. in Bedford-Stuyvesant on Oct. 2, 2023, when a man, later identified as Dowling, passed by them. Carson and his girlfriend stood up and started walking in the same direction when Dowling started kicking and knocking over parked scooters on the corner. “The f–k are you looking at,” Dowling yelled twice. “Imma kill you right now!” A screengrab from a video showing Ryan Carson, 32, and his girlfriend sitting on a bench at a bus stop as their attacker passes by them. Carson repeatedly asked Dowling to “chill,” but he lunged instead,backing the victim and his girlfriend toward the bench they were sitting on. But the attacker instead lunged at the 6-foot-4 victim, backing him and his girlfriend up toward the bench they were sitting on. He punched Carson, then knifed him several times as Carson’s girlfriend begged, “Please stop! Please stop!” “Many of us still shudder when recalling the horrific video showing this defendant viciously attacking Ryan Carson and stabbing him to death for no reason at all,” Brooklyn D.A. Eric Gonzalez said. “Such an unconscionable crime requires the separation of this defendant from our society for a very long time, which is ensured by the promised sentence he’s now facing.” A screengrab from the video showing the stabbing death of budding public policy advocate Ryan Carson. Carson was described as “one of the rising stars in our organization” by the executive director of the nonprofit New York Public Interest Research Group, where he worked as a senior solid waste campaign director. He was working on a project with groups representing bottle and can collectors pushing for legislation that would expand the types of bottles and cans that can be redeemed for tax refunds, as well as increase the 5-cent deposit fee.