On January 24, 2013, the Florida Department of Corrections received a grievance letter from an inmate named Harold Hempstead, who had been imprisoned at the Dade Correctional Institution. The letter was brief and its tone was matter-of-fact, but the allegations it contained were shocking, raising troubling questions about the death of a mentally ill inmate named Darren Rainey, who had collapsed in a shower seven months earlier, on June 23, 2012—a case that I wrote about in the magazine this week. According to Hempstead’s letter, the death had been misrepresented to disguise the abuse that preceded it. The reason Rainey collapsed in the shower, Hempstead alleged, was that he had been locked in the stall by guards, who directed scalding water at him. Hempstead’s cell was directly below the shower. That night, he had heard Rainey yelling, “I can’t take it no more,” he recalled. Then he heard a loud thud—which he believed was the sound of Rainey falling to the ground—and the yelling stopped. Hempstead concluded his letter by calling for an investigation.

A week after receiving this information, the Florida D.O.C. sent Hempstead a terse response. “Your grievance appeal is being returned without action,” it stated. In the months that followed, Hempstead continued to file grievances with the D.O.C. He also wrote to the Miami-Dade County Medical Examiner Department and to the Miami-Dade police. At first, nothing appears to have been done in response to the letters, which is perhaps not surprising: prisoners routinely level false accusations at guards. Hempstead’s allegations might have carried more weight if an employee at Dade had backed them up. However, as I noted in my article, the psychiatrists in the mental-health ward at Dade feared (reasonably) that reporting even minor misconduct could trigger harsh retaliation from the guards, putting their own safety at risk. When Hempstead turned to some counsellors for support and guidance, they urged him to keep his accusations vague and to stop “obsessing” about Rainey. But Hempstead, who has been diagnosed with obsessive-compulsive disorder, was determined to get the word out. With the help of his sister, Windy, he eventually contacted the Miami Herald, which, on May 17, 2014, published a front-page story on Darren Rainey, called “Behind bars, a brutal and unexplained death.”

The literature on whistle-blowers is full of stories about moral crusaders who risk everything to expose misconduct and succeed only in upending their own lives. (This is one of the themes of my own book on the subject, “Beautiful Souls.”) At first glance, Hempstead’s story appears to veer dramatically from this script. Prompted in part by the revelations he made, the Justice Department has launched an investigation to determine whether Rainey’s death was part of a broader pattern of abuse. Some of the guards in the mental-health ward at Dade have been reassigned. The Florida D.O.C. has adopted a series of reforms, including crisis-intervention training for corrections officers and other steps that may deter future violence.

But it is also possible that Hempstead’s story will end less happily, particularly when it comes to the question of whether justice will be done. Although investigations are ongoing, none of the guards who allegedly took Rainey to the scalding shower have been charged with any crimes. (They have since resigned, and their files included no indication of wrongdoing.) Earlier this year, an autopsy of Rainey that was forwarded to state prosecutors ruled the death “accidental,” and did not recommend criminal prosecution.

Meanwhile, Hempstead has paid a steep price for exposing the circumstances under which Rainey died. After the reporter Julie Brown, of the Miami Herald, interviewed him, several corrections officers threatened him with solitary confinement. Hempstead has since been transferred to another prison and placed in “protective management” status by the D.O.C., but his reputation as a whistle-blower (“Miami Harold,” as some now put it) has not been forgotten, and will follow him as long as he remains behind bars.

That will be a long time: specifically, until 2161, the year Hempstead will be released, if he somehow lives long enough to serve the hundred-and-sixty-five-year sentence that Judge Brandt Downey handed him, in 2000, for his involvement in dozens of house burglaries. Hempstead, who is now forty, was twenty-two at the time. He was born in St. Petersburg, Florida, the youngest child of an alcoholic father, who died when Hempstead was seven. For a time, Hempstead was paid by police officers for tips. His mother was institutionalized because of mental-health issues, according to his family, leaving Hempstead and his siblings to fend for themselves on the streets. It was an extremely chaotic upbringing, his sister Windy told me. This failed to move Judge Downey, who called Hempstead “a despicable human being” at his trial, and told him, “I hope you die in prison.”

Hempstead has denied that he was directly involved in the burglaries, admitting only that he fenced stolen goods. Whatever the case, it’s hard to avoid seeing what amounts to a life sentence for a series of property crimes as grossly disproportionate. “By anyone’s definition of a proper sentence for a crime, even multiple burglaries, that’s just absurd,” Randall C. Berg, Jr., the executive director of the Florida Justice Institute, told me. The sentence seems particularly misplaced given what’s happened since. In 2006, Judge Downey agreed to retire early when it was revealed that he had repeatedly downloaded pornography onto the computer in his courthouse (“I feel in my heart that God has forgiven me,” he said).

Hempstead’s sister Windy, who calls him Joey, was one of the first people he spoke to after Rainey died. He told her that he had “crouched in his cell with his hands over his ears, shaking,” she told me. “That night will never leave my brother.” When I met Hempstead, a wiry man with a measured bearing, he gave no indication of this. But near the end of our interview, when I pressed him for details about the night Rainey died, he balked. “It might get me crying,” he said.

According to Berg, Hempstead could try to challenge his conviction on technical grounds, but the odds of getting a retrial are long. Florida’s governor, in conjunction with the Executive Clemency Board members, also has the authority to review the facts in his case and decide to commute his sentence. But the current governor, Rick Scott, is a Republican not known for leniency with prisoners, even a model prisoner convicted of crimes less grave and violent than the brutal one he brought to light. The irony is not lost on Hempstead. As he told the Miami Herald last year, “You know, I made a lot of mistakes in my life, but nothing I did resulted in somebody dying.”