"Midway through my first year as a newspaper reporter, I walked through a two-story apartment building in Brownsville, Texas, where a poor young couple had murdered their three children," explains Laura Tillman in the opening sentence of a new book analyzing that crime and its aftermath. Tillman was sent to this unlucky address to cover the debate about whether the building at 805 E. Tyler St. should be demolished, not only because it was falling down but because it was an ongoing symbol of horror and grief to the community.

She would spend the next seven years obsessed with what can only be called an atrocity — the smothering, stabbing and decapitation of children 2 months, 14 months and 3 years old by their parents, aged 22 and 23. She interviewed scores of neighbors, lawyers, police and experts and, most significantly, carried on a lengthy correspondence with John Allen Rubio on death row. (His common-law wife, Angela, serving three consecutive life sentences, didn't respond to Tillman's overtures.)

Tillman quotes John Allen's letters at some length, breathing life into the account of his childhood and character. There would be no way to paraphrase lines as heartbreaking and confounding as these: "I have always wanted to be a father since back when I was a little kid. I promised myself I would be a great dad, nothing like my dad and for the short time I did have with my kids I was, until this happened that is."

Although she was cautioned at the outset that a crime like this is a "black hole" offering no lessons or value, the author was determined to plumb it for herself.

To get to whatever wisdom might be attained, she must first go through the heart of the horror. "Don't Read This Chapter Before Going to Bed" gives a blow-by-blow account of the murders. Equally horrific is her description of the crime scene photographs. When she finds herself inside the apartment during one of her obsessive visits to the building, she is so shaken by what she encounters that she throws away the sneakers she was wearing.

On the other side of these details lies a dogged attempt to understand what happened, a review of the psychological, sociological and spiritual explanations for the crime (John and Angela claimed that they killed their children because the youngsters were possessed by evil spirits), a meditation on the death penalty and on the city of Brownsville.

"The Long Shadow of Small Ghosts," by Laura Tillman

Tillman closes with a last look at the building, still standing. Behind it Tres Ángeles Community Garden now thrives, its name recalling the "three little angels" who "live in each root and stem and leaf." The short lives of these "small ghosts" are given lasting meaning in this book.

Marion Winik is the author of "The Glen Rock Book of the Dead." She teaches nonfiction writing at the University of Baltimore.

The Long Shadow of Small Ghosts
By: Laura Tillman.
Publisher: Scribner, 241 pages, $26.