His phone began to ring in earnest: Junnier, it turned out, was in the hospital, slightly wounded in the face and leg. (Not by Kathryn Johnston, it would eventually be revealed, but by bullets fired by other police officers.) Friends called, jubilant — they had seen the notorious cop’s picture on TV and were delighted by his misfortune; Junnier was widely hated by drug dealers. White was not sad about that side of it — Junnier had it coming. But White could see (though not admit to his friends, who were unaware of his sideline) that, if his handlers got taken down, this could be bad for him financially. And it would be bad for him in every way if they dragged him down with them.

As a low-rent secret agent of sorts, White couldn’t talk to many people about his situation. But there were a couple: Antrecia and an uncle. White also knew some federal law-enforcement agents. His reputation as a reliable informant had spread within the law-enforcement community, and he says he worked with the Atlanta office of the federal Bureau of Alcohol, Tobacco and Firearms (A.T.F.) on several busts of illegal gun dealers while fully wired and monitored by vehicles outside the meeting place — by the book, in other words. (The A.T.F. would not comment. White says he was also used by the Secret Service on a counterfeiting case; the Secret Service would not comment, either.)

According to an F.B.I. report assembled from interviews with numerous officers in the months that followed, White called his A.T.F. agent, Eric Degree, who drove over the next morning. After White unburdened himself, Degree advised him not to take calls from his narcotics handlers and to keep him apprised of developments. Minutes after Degree left, White says, Junnier, out of the hospital, called — and White, unable to resist, answered. Junnier wanted to go over the story that Smith and White had settled on and to make sure White was still with the program. “Uh-huh,” White said as he listened. Junnier said that detectives would be coming by White’s mother’s house to show him a photo lineup of people who could be “Sam,” the man who supposedly sold him crack.

White’s understanding of what happened next diverges from the account that can be pieced together in the F.B.I. report. White told me that he was worried that Scott Duncan, the narcotics detective who came by, could be in cahoots with Junnier, and had come to rehearse White’s agreed-upon story and to test his loyalty. The F.B.I. report, by contrast, paints a picture of a detective innocent of the cover-up, sent by superiors trying to find Sam.

The F.B.I. report confirms that Duncan and White met at an intersection near his mother’s house. White says that he never intended to get inside the car but that he did to remain inconspicuous when some young men drove by. And he meant to keep the door ajar as well, but in a moment of inattention, it clicked shut.

Once inside, the child locks were on, and he worried that he couldn’t get out. They drove to a vacant lot, where Duncan parked and had White tell his story while the car idled. Next they drove over to Neal Street. White grew increasingly nervous. They came to a stop outside the county jail. White said that Duncan and another detective in the car, who never identified himself, told him they were there to collect the photo lineup. But instead, they left him in the car while they stood outside and made phone calls that White couldn’t hear.

White called Degree of the A.T.F. — he wanted him to know the mess he believed he was in, and the danger. At one point, according to the F.B.I. report, Degree instructed him to pass his phone to the officers; he told Duncan that he needed to see White in his office when he was done. The detective replied that he needed to keep White for a while, that the photos weren’t ready, and handed the phone back. White, now increasingly paranoid, wondered whether he was going to be killed — that way he could never undermine the cover-up. His fear growing, he called Degree again. This time, he says, the federal agent told him that he had to find a way to get out of that car.