They walked free. Until a reporter knocked at their door.

In the mid-1960s, Mississippi and Alabama were the scenes of some of the most infamous crimes in American history. In June 1963, Medgar Evers – the Mississippi field director for the NAACP – was gunned down in his driveway in Jackson. A year later, three civil rights workers were murdered near Philadelphia, Mississippi. Most horrific of all was the Ku Klux Klan bombing of the 16th Street Baptist Church in Birmingham, Alabama. Four girls were killed. Three were 14 years old. The youngest was 11.

The crimes were compounded by the absence of justice. Evers’ killer, Byron De La Beckwith, was prosecuted twice, but both trials ended with hung juries, despite ample evidence of his guilt. The state of Mississippi refused to prosecute the killers in the Philadelphia case; they were ultimately prosecuted in federal court for violating the victims’ civil rights. None of them served more than a few years. Of the four Klan members who carried out the 16th Street church bombing, only one was convicted of murder – 14 years later.

In 1988, Jerry Mitchell, a Jackson reporter, went to the press screening of “Mississippi Burning,” a film loosely based on the Philadelphia killings. He was horrified to learn – from a former FBI agent sitting next to him in the audience – that the perpetrators, like many others guilty of racist atrocities during the civil rights era, were walking free and living as if nothing had happened.

He decided to do something about it. “Race Against Time: A Reporter Reopens the Unsolved Murder Cases of the Civil Rights Era” is the story of Mitchell’s quest to uncover enough evidence to persuade state prosecutors in Mississippi and Alabama to reopen the cases.

Getting authorities to reactivate cases that had been cold for more than 20 years is a daunting task under normal circumstances. 

Mitchell faced obstacles that would have defeated many other journalists: Police files on the murders were brief and uninformative; in the Evers case the trial transcript was missing; the records of the State Sovereignty Commission – the arm of the Mississippi state government founded to fight the civil rights movement – had been sealed by court order; anyone who had read Sovereignty Commission files and shared what they knew risked going to prison. Mitchell himself was subjected to intimidation and threats.

“Race Against Time” provides the pleasures of both a detective novel and a courtroom drama. As Mitchell recounts how he sifted through court records, reread FBI files, and got suspects to talk, we get the thrill of watching an old-fashioned investigative reporter at the top of his game. And at trial after trial, we see prosecutors relentlessly establish the guilt of men who had gone unpunished. 

We also come to see a personal element in Mitchell’s work, as he becomes friends with Myrlie Evers, Medgar’s widow; he sees the guilty verdicts as bringing some kind of closure to the victims’ families.

And the raw material for “Race Against Time” is storyteller’s gold: a compelling pursuit of justice combined with a real-life Southern Gothic atmosphere. 

Mitchell talks to an unrepentant killer who justifies his racism with twisted interpretations of the Bible and bizarre conspiracy theories. He tracks down a murder weapon to the bedroom closet of a district attorney. And at the murder trial of a former Klansman, the defense attorney regales the court with an effusive retelling of Hitler’s life story.

Most of the crimes Mitchell investigated were committed in Mississippi, and he does a chillingly effective job of re-creating the climate of hate and terror. At the time, the editor of the Jackson Daily News referred to black civil rights activists as “chimpanzees” in his columns. 

Mississippi politicians and law enforcement colluded with the Ku Klux Klan in the physical abuse and murder of civil rights activists: One of the perpetrators in the Philadelphia murders was the local sheriff. Most disturbing of all was the fear felt by journalists, investigators, and witnesses during trials that took place as late as 1998. 

Despite the many virtues of “Race Against Time,” Mitchell (the winner of more than 20 national awards, including a MacArthur fellowship) is a better investigator than he is a writer. As a narrative, the book is uneven and many of the officials could have been fleshed out better as characters. At times, Mitchell has a folksy tone that belies the seriousness of his topic. For example, when considering the possibility that a witness might be dead he writes, “For all I knew, he was pushing up daisies in a cemetery.”

Nevertheless, “Race Against Time” is an important and often compelling book. And Mitchell is a national treasure.