She made a note that the case “warrants a closer look,” and then, in June of 2019, another envelope arrived from Chestnut. This time, he had enclosed the police’s investigatory reports. Brian Ellis, the investigator for the Conviction Integrity Unit, was in Lipscomb’s office when she opened the envelope and pulled out the reports, including the one cataloguing leads that the police had received soon after the murder. She started reading, passing each page to Ellis as she finished it. “Are you seeing this?” she asked.

That summer, Bishop received a brief letter from the state’s attorney’s office, citing State v. Alfred Chestnut, et al. “We need to speak with you about the case at a time and place convenient for you,” the letter read. Bishop was now fifty years old, but the letter frightened him, and at first he did not respond. “I was shaky, anxious, nervous,” he recalled. “I felt like it was a trap.” He worried that he might be sent to prison for lying in court in 1984, or for some fabricated crime connected to the murder.

After mulling the letter over for several days, however, he decided to respond. “I’m tired of living this lie, that those three guys did it,” he explained later. “If I have to tell the truth and it sends me to prison, I’ll go to prison.”

On August 8, 2019, he walked into Lipscomb’s office to meet with her and Ellis. They could tell that he was nervous. He kept his gaze down, exhaled loudly, paused between words. But he spoke clearly about the day his friend had been killed, how he had been threatened with arrest if he did not coöperate with law enforcement, how he had lied at the trial. “There was one shooter, and it was Michael Willis,” he said.

Lipscomb asked Bishop to walk through the crime scene with her and Ellis, and five days later he met them at his old junior high school. He had not been back since 1984, but he remembered where he and Duckett had attended their last class together, the route that they had taken to the cafeteria, and the spot where the shooter had confronted them. The visit felt like an “out-of-body experience,” Bishop said later. “I’m looking at myself as a fifty-year-old man, and then I’m hearing my voice saying ‘Oh, this is what happened’ as a fourteen-year-old kid.”

Lipscomb and Ellis knew it was unlikely that, thirty-six years after the crime, the three other students who had testified for the prosecution would all be alive and willing to be interviewed. But it turned out that they were. All three shared what they remembered from the day of the murder, and their memories did not match what they had said at the trial. The female student who had first identified the defendants admitted that she had not even seen the shooting. She had been the youngest of the students who testified for the prosecution; before the trial, she recalled, she had attended so many meetings that she did not know “who was who.” Lipscomb concluded that all the students who had testified for the prosecution had been “coerced and coached.”

Lipscomb set herself a deadline: she would do everything she could to get Chestnut, Watkins, and Stewart freed before Thanksgiving. For four weeks, she spent nearly every waking hour working on a report for Mosby about the case, rereading witness interviews and police documents and hundreds of pages of trial testimony. In her report, she quoted someone who had known the victim and the three men who went to prison, who said, “Everyone knows Michael Willis shot DeWitt.”

On November 22, 2019, Mosby took a trip with Lipscomb and Ellis to three prisons, to visit the men incarcerated for Duckett’s murder. None of them were aware that Mosby was coming. Ransom Watkins, who was at Patuxent Institution, a maximum-security prison in Jessup, was working in the shop that day. Guards hurried him into a room near the prison’s entrance, and through a window he could see a large group of officers staring at him. “Next thing I know, I see Marilyn Mosby come through the door,” he said. “She’s, like, ‘Do you know why I’m here?’ I’m, like, ‘No, not really, but I’m hoping it’s some good news.’ She’s, like, ‘We’ve heard your cries. You’ve been crying for thirty-six years, and we’re here to answer them. You’re going home.’ ”

Three days later, the men were taken to a courthouse in downtown Baltimore. Chestnut and Stewart had been in the same prison the year before, but Chestnut and Watkins hadn’t seen each other in nearly twenty-five years. Chestnut recalled, “When they first saw me, both of them were, like, ‘Man, you did it!’ ”

In the courtroom, a judge apologized to the men, then set them free. “You could hear the sighs of relief,” Stewart said. “My mother was crying, my sister was crying.” Chestnut’s mother was also there. Watkins, however, was missing his closest relatives. “It was kind of bittersweet for me,” he said. “I had lost my mother, father, sister, brother, and everybody.” Outside the courthouse, a small crowd gathered to celebrate their release.

In early 2020, I met with Lipscomb in her office to learn more about this case. Three months had passed since she had finished her reinvestigation, and she was still livid. Speaking about the prosecutorial misconduct that she had uncovered, she said, “This is absolutely the worst that I have seen.” Why did the prosecutor refuse to give the police investigatory reports to the defense lawyers and then bury them in the court file? “I haven’t spoken to anyone yet who can explain why that occurred,” she said. (She couldn’t ask the prosecutor; he had died in 2016.) Among her other findings was a prison record from years earlier in which, she wrote in her report, Watkins said that the “arresting detective” in his case, Kincaid, had told him, “You have two things against you, you’re black and I have a badge.”

The way the police had treated the teen-age witnesses in this case had alarmed Lipscomb, too. Each of the three boys had been brought to the homicide office without a parent, and, at one point, the mother of one of them had come to Police Headquarters searching for him. “He could hear her from the interrogation room raising hell: ‘Let him out!’ ” Lipscomb said. “I just can’t imagine a scenario where these officers would have arrived at a high socioeconomic group in the suburbs and taken three teen-agers without notifying their parents.”

In wrongful-conviction cases, there are often secondary victims: individuals who, having helped incarcerate an innocent person, must confront their own culpability once that person is freed. They can include the jurors who unintentionally convicted the wrong person, and the judges who sentenced those people to prison. Bishop’s situation was slightly different, because he’d known that the defendants were not guilty when he testified against them. But “he was a teen-ager at the time and a direct product of what was happening to him by the police, by the prosecutor,” Lipscomb said. “He set out to do the right thing.”

In Lipscomb’s report, she hid the identities of the students who had testified at trial. Bishop became Student No. 2, and it was evident that he had played a critical role in getting the convictions overturned. He had never spoken to the media about the case, and when I asked Lipscomb if she thought he might be willing to be interviewed she seemed doubtful. But she agreed to pass on a letter, and, as it happened, Bishop had more he wanted to say. He e-mailed me in May of 2020, and when I called him he spoke for more than three hours. (My efforts to speak to the other students were unsuccessful.)

In that call, Bishop described Duckett as “one of the nicest guys ever,” the sort of teen-ager who would “hold the door for the teacher.” He added, “I always thought about what he would have been.” Their school had provided counselling after Duckett’s murder, he recalled, but “to me that little counselling session didn’t even exist because that’s how numb I was. All the grief has been happening over the past thirty-six years.”

He continued, “There’s so many variables . . . feeling shame and guilt, nightmares, flashbacks, all that stuff. And I’m not trying to paint a picture of ‘Oh, feel sorry for me.’ No, I’m fine. I’ve been fine. Been living a good life, I guess.” He did not sound convincing. Chestnut, Watkins, and Stewart had been free for six months, but it was apparent that he was still tormented by his role in sending them to prison. “Those feelings and that history—it will never go away,” he told me. “It’s been a lifelong curse.”

Today, Bishop lives with his second wife in a house in East Baltimore. He has a job at a psychiatric facility, where he teaches coping skills to young patients dealing with depression, extreme anger, auditory hallucinations, and histories of self-harm. They call him Mr. Ron. “I love working with challenging kids,” he said.

Despite having worked in the mental-health field for many years, Bishop has never sought therapy for himself. In the past year and a half, I interviewed him many times, and he seemed to appreciate the chance to unburden himself of secrets that he had held close for decades. “You’re the first one I’ve ever really gotten into detail with about this case,” he told me during our first call. “I’m not trying to get attention from all this—this is more healing to me.”

This past June, I went to Baltimore to meet Bishop. We spent the day driving around the city, starting at his old junior high school. Students were on summer break, and the corridors were quiet. Bishop led me to the scene of the crime, on the second floor. Visiting the hallway did not make him overly emotional—“I’m just numb,” he said—but his ability to remember specific details from 1983 was uncanny. He pointed to the area where the gunman had approached him and Duckett, near locker C-2335.

Bishop then took me to the cafeteria. He stood in the center of the cavernous room for a while, remembering everything that had happened the day Duckett was shot. “Just to see him run in the cafeteria holding his neck—we thought he’d be O.K.,” Bishop said. But after the bullet had entered Duckett’s neck it travelled downward and punctured his lung. Before we left the school, Bishop pulled out his cell phone and took a photo near the entrance. “This might be my last time in this place,” he said.