Although this process amounts to a litany of legal outrages, its effect is primarily very sad. Mr. Williamson was an aspiring baseball star whose career was ruined by the time he was 24. “Man, you’re gonna die in the minors,” he was once nastily told by his hero, Reggie Jackson. That was Mr. Williamson’s closest brush with baseball stardom.

Image John Grisham Credit... Lynne Brubaker

The book provides much evidence of Mr. Williamson’s mental deterioration. His behavior becomes wildly erratic. His substance abuse heightens. His habits turn increasingly peculiar. (At one point he refuses to discuss anything unrelated to presidents of the United States.) Meanwhile Mr. Grisham brings his extensive legal expertise to the job of being dumbfounded by what he describes as the law’s systematic flouting of Mr. Williamson’s rights and by the sadistic manipulation of his paranoia.

In the face of such flagrant abuse of a suspect, Mr. Grisham has a hard time keeping sarcasm at bay. Of the terrible circumstances surrounding the death of Mr. Williamson’s mother, and that he was kept shackled even at her funeral, the author writes: “Such precautions were obviously needed for a felon who forged a $300 check.” (At that point the murder charge had not been brought against him.)

Far worse than her son’s humiliation is that Mr. Williamson’s mother died thinking that she had proved to the police that her son was home watching videos with her on the night of Debbie Carter’s murder. Though her lawyer said he watched her make this statement to a police detective, a video camera apparently failed to record what she said. No evidence of it surfaced in the legal proceedings that followed.

“The Innocent Man” is plural, despite its title. It is about “four men, four average white guys from good families, all chewed up and abused by the system and locked away for a combined total of 33 years.” This is a lot for a nonfiction narrative to juggle, and this book sometimes strains under the burden of so much grim, frustrating data. Mr. Grisham’s report on the construction of an underground, completely daylight-deprived prison provides the most egregious chamber of horrors in a book that is figuratively full of them.

Every now and then “The Innocent Man” provides a tangible reminder of Mr. Grisham’s novels. Take Barney Ward, Mr. Williamson’s court-appointed lawyer, who sounds as if he walked right out of Grisham fiction. This is Mr. Ward’s first death penalty case. He is a wildly colorful character. He is also blind; and just as the case pivots on forensic evidence that requires visual examination, his assistant leaves him in the lurch. Mr. Ward’s relationship with Mr. Williamson is so edgy that Mr. Ward’s son is poised to tackle the client physically should trouble arise.

If this were fiction, Mr. Ward would triumph. And he’d do it in style. But he neglected to use crucial evidence that could have helped his client. Mr. Williamson was eventually assigned a different lawyer. His vindication was bittersweet at best. The process that finally brought him justice could not bring him peace.