The question of who shot, raped, and burned the bodies of four teenage girls at an I Can’t Believe It’s Yogurt! shop in Austin, Tex., in December 1991 continues to vex local enforcement. Some say it was a Mexican biker gang, while others believe it was a group of rampaging teenage boys. The case has been in and out of the courts, with dozens of attorneys, investigators, and others playing a role in the drama.

Austin was considered a sleepy town at the time, full of students, hippies, and cosmic cowboys. “It was the good place, the kind of place that people never expected a crime of this magnitude to occur,” says Beverly Lowry, whose new book, Who Killed These Girls?, takes its name from billboards that went up around town shortly after the murders. “It’s been said that this was the day Austin lost its innocence,” Lowry notes, over a breakfast of scrambled eggs and (for me) cream biscuits at a diner in booming hipster East Austin, where Lowry has lived for several years. “But,” she asks, “what town is really innocent?”

And truth be told, Austin in 1991 was far from it. After all, it was the site of the 1966 shooting rampage by Charles Joseph Whitman at the University of Texas, in which 49 people were shot and 16 killed. “And in the months before the Yogurt Shop Murders, there were several brutal crack-related killings, while the month following there was another abduction-murder at a local car wash,” Lowry says. “So let’s admit that Austin was hardly crime free.”

The murders drew the fascination of Lowry only years later, when after seeing yet another front-page story in the Austin-American Statesman about the ongoing court cases related to the killings, she asked her son, who has lived in Austin for years, “Will we ever be rid of the Yogurt Shop Murders?”

“He looked at me and replied, ‘No, Mom. They will be with us forever.’ That really stuck with me.”

Lowry, now 78, has lived in and out of Texas and in and out of the Austin area for years, having spent time teaching in Houston, as well as Buffalo, N.Y.; Missoula, Mont.; and Washington, D.C. Born in Memphis, she was raised in Greenville, Miss., and is the author of half a dozen novels set in Texas and Mississippi, starting with 1977’s Come Back, Loly Ray and going up to 1994’s The Track of Real Desires. For the past 20 years, her focus has been on nonfiction, including 2007’s Harriet Tubman: Imagining a Life; Her Dream of Dreams: The Rise and Triumph of Madam C.J. Walker (2003); and the book for which many remember her, Crossed Over: A Murder, A Memoir (1992).

Crossed Over tells the story of Karla Faye Tucker, Houston’s notorious “pickaxe murderer” who, when she was put to death in 1998, became the first woman executed in Texas since 1863. In the book, Lowry reveals that she was herself coping with the then-recent death of her teenage son in an unsolved hit-and-run and describes the emotional challenges of grief—something that unexpectedly bonded her to Tucker. The result is a surprisingly sympathetic portrait of a murderer who is said to have claimed that she experienced an orgasm with each swing of her ax.

Lowry says that she “got very close to Tucker—some say it was too close.” She adds, “But the same type of bonding happened with Barbara [the mother of one of the Yogurt Shop victims]. I found that I could empathize with her because I too had a child who was murdered and the case has remained unsolved.”

Who Killed These Girls? took nearly a half-dozen years of diligent research. Helpfully, several key figures opened up to Lowry, and, even better, many had kept thorough records—transcripts, police reports, journals, and videos of the interrogations—and gave them to Lowry for her research. The primary sources were invaluable in Lowry’s reconstruction of the narrative timeline, something she says she wrote out by hand and that took up nearly 250 pages. “I was documenting the crime, the progress of the investigation, as well as all the events that might have otherwise been in the consciousness of the people involved at the time.”

And the reason that timeline is so long is because the case itself is byzantine. Four men, teenagers at the time of the murders, were indicted for the crime, but all eventually were released. And it is here—in explaining just how manipulative law enforcement was in handing interrogations and evidence—that Lowry takes full advantage of her primary sources. “I was watching the video of the interrogation of one of the suspects, Michael Scott, and it was fascinating to see just how easy it is to create a narrative through repetition. It was so pathetic to me and so terrible how they turned [Scott] into the killer. If this book does anything, I think it’ll be hard for anybody to say nobody confesses to something they didn’t do.”

Lowry dedicated the book to Gary Fisketjon, her editor at Knopf. “It’s the first time I dedicated a book to someone other than a friend or family,” she says. “Gary saw the potential in the book even when it was a shadow of itself. He’s just been great and has really stuck with me. It’s not as if this is a huge money spinner for them.” Lowry is one of several major Austin authors published by Knopf; the list includes Lawrence Wright, Steven Harrigan, and Sarah Bird, though they have all worked primarily with editor Ann Close.

As to whether this new book can be viewed as something of a companion piece to Crossed Over, Lowry won’t say. “That is up for the readers to decide.” Either way, the book does reflect various interests for Lowry, who also teaches an online class for University of Houston–Victoria on crime writing. “It’s very popular,” Lowry notes. “I think there’s a strong interest in this genre in Texas. There was a time, especially during the oil-boom years, when it seemed like a lot of rich women were killing their husbands, and that produced some good books.”

“But as Luc Sante points out in the introduction to Classic Crimes by William Roughhead, this genre has been around a long time,” Lowry says. “I teach everything from In Cold Blood to Dave Cullen’s Columbine. What’s interesting to see is how crime has intensified. For example, when you look at Gary Gilmore’s crime that Norman Mailer wrote about in The Executioner’s Song, things have gotten much worse.” What has also evolved is the level of sophistication with which the police can conduct such an investigation. “People forget that nobody paid attention to DNA until the CSI TV series debuted, and that was 2000. And the first arrest and conviction based on DNA was only in 1988, and that was in England.”

Though she draws no absolute conclusions as to who may have killed the girls, and the case continues, Lowry is content to put out Who Killed These Girls? and let the chips fall where they may. Certainly, the timing is right for the book, with the public eager for true-crime stories that have plenty of ambiguity: one needs only to think of the popularity of Making a Murderer and Serial.

But it’s important to remember that it’s easy to sit on the sidelines as a reader or viewer, and another thing altogether to be immersed in the case itself. “I have lost friends, and people have stopped talking to me after I expressed doubt about their theory of who committed the Yogurt Shop murders,” Lowry says. “But that’s okay. I just don’t think that they understand that that’s what we do. We’re writers. We try to see things in new way; we thrive on ambiguity. Sometimes we get to the truth. Sometimes we don’t. But the one thing we do is make it hard for people to ever forget.”