Alexandria Marzano-Lesnevich first learned about Ricky Langley in a sticky Louisiana law office in the summer of 2003, right after his second trial concluded. It was during that trial that the initial sentence of the death penalty had been overturned, and more than a decade since Langley had committed and confessed to the murder of six-year-old Jeremy Guillory.

Marzano-Lesnevich was a Harvard Law student when she took the internship in Louisiana, and she chose Louisiana specifically because the firm needed help fighting death penalty cases. When shown the tape of Ricky’s confession on her very first day, something unexpected happened. Suddenly, shockingly, she wanted Ricky to die. “When I watched his confession tape for the first time, my reaction threw me into turmoil,” she says. “I very much had this idea of the law as a place where we put personal feelings aside and we focus on the reasoning process. So for me to go [to Louisiana] and be shown something that so ruptured that because it collided with my past, it threw me into this feeling of disarray.”

The Fact of a Body: A Murder and a Memoir pivots around this moment. From the instance she watches the taped confession, Marzano-Lesnevich’s life moves backward as it moves forward. The past she’d tried to leave behind suddenly was all she could think about, and its unexpected parallels to Langley’s own troubled past become more and more apparent during nearly a decade of researching and writing this book.

Full of dramatic turns and unthinkable transgressions, Marzano-Lesnevich’s exquisite prose weaves together a story so taut and gripping that it’s sometimes hard to remember that the book is nonfiction. For Marzano-Lesnevich, because of the content that the book contains, she knew it had to be written this way. “I had to make the pages turn because I was asking the reader to get through a lot,” she says. “And I know that I’m that kind of reader; I like to be told a damn good story.”

And it is a damn good story. But it’s also not for the timid. With brutal honesty, Marzano-Lesnevich not only examines the murder of young Jeremy, but Ricky’s broken life, the legal system’s troubling shortcomings, and the dark secrets families keep. Not far into the book, it is revealed that before killing Jeremy, Ricky had a history of pedophilia. This link resonated deeply with Marzano-Lesnevich, who as a young girl suffered repeated sexual assaults at the hands of her grandfather.

It was this memory of her grandfather, she realized later, that had thrown her into disarray that first morning in Louisiana. “I had been so shocked by the way that I clearly saw Ricky through the lens of my grandfather,” she explains. “I felt like I should have been able to lay my past aside. The real shock was discovering how many people saw Ricky through the lens of their own past. I thought I had failed to do it, and failed to live up to the offices of the law, and then I got the records and I discovered a trial just works that way.

“The legal system functions as much as a truth-making mechanism as it does as a truth-finding one,” she continues. “It’s really important to think of it as not necessarily finding out what happens, but making a story of what happens and then we call that story the truth.”

So what truth is to be found here? Truth: Ricky Langley killed Jeremy, hid his body for three days, then confessed. A simple case, it seems. But three trials, nearly two decades, and 30,000 pages of documented records later, and perhaps there’s only one other definitive takeaway: there is no such thing as a simple murder. There is no such thing as a simple life. Langley is both a murderer and a boy with his own troubled past. Marzano-Lesnevich’s grandfather was both “loving, at times, in his own way,” and “the man who molested” her. For Marzano-Lesnevich, years spent trying to to turn her back to the latter fact, the one that propelled her into this story for a decade, proved impossible. “The past is in our body. The past is coming with us. The thing that let me live with it was to accept the duality of it,” she says. “In the legal system we tend to make a simple story and that covers up what really happens, it covers up the complexity of the narrative. I think we tend to do that in our own lives, too. If something bad happens we want to get away from it, so we make a simpler story, but that in itself could do harm. If there’s a goal for the book it’s to make space for complexity.”

Alex Layman is a writer living in Austin.