Confirming the sex of the postcranial bones wasn’t as easy as you might think. During childhood, there’s very little skeletal difference between male skeletons and female skeletons; it’s only during puberty, when the female hips widen and the pelvic cavity deepens, that the difference becomes pronounced. Fortunately, one skeletal feature does hint at the difference, even early on: in females, the sciatic notch — the gap in the lower hip where the sciatic nerve emerges from the spine and enters the leg — begins to widen in the very earliest stages of puberty. The sciatic notch in the ilium from the field in Lenexa was the width of two of my fingers, which made it twice as wide as a male’s would be. The skull had sharp-edged eye orbits and a smooth forehead, as well as small muscle markings in the occipital region — all signs of a little, lightly muscled female.
By now I was almost certain that the bones all came from Lizabeth Wilson. But sometimes, especially in murder cases, “almost” isn’t quite good enough. Was there a way to make sure? I thought there might be.
My stepfather, Charlie Bass, was a geologist by training. That meant that as a child I was treated to numerous informal lectures and demonstrations highlighting the properties of various rocks and minerals, including the surprisingly dramatic glow some minerals gave off when illuminated with ultraviolet light, or “black light.” In daylight, for instance, the mineral fluorite is a drab, chalky color; in a dark room under UV light, though, fluorite glows a brilliant blue; the mineral calcite shines bright red; and aragonite gives off a neon green. If you’ve ever stepped into a teenager’s cavelike room decorated with black-light posters (less common now than they were in the 1970s, when my three sons were growing up), you’ve seen another version of UV fluorescence in action.
Bones are composed largely of minerals — calcium phosphate, mostly, with dashes and pinches of other minerals thrown into the mix, for reasons I don’t pretend to fathom — so if you shine UV light on a bone, it will fluoresce slightly. I knew that Lizabeth Wilson’s bones should all fluoresce at the same wavelength, or glow the same color. And since differences in heredity, diet, and other factors make every person’s bone chemistry unique, I also knew that anyone else’s bones should fluoresce at a slightly different wavelength or color than Liz’s.
That, at least, was the theory. In practice, though, it wasn’t quite that simple and clear-cut. I’d tried the technique in several other cases by this time, and I’d noticed that the differences in the color were not as dramatic in bone as in geologic specimens displayed in museum cases. I’d also observed slight differences among bones from the same individual. Did the decay process affect the bone chemistry slightly, and inconsistently? If some bones were protected and some exposed to the elements, would that make a difference? So while I had reason to hope that UV fluorescence could confirm that all fourteen of these bones were Lizabeth Wilson’s, I couldn’t be certain of that until we turned out the lights and turned on the UV lamp.
To minimize the chance that environmental factors — trace minerals in drinking water, for instance — might skew the results, I decided to compare the Lenexa bones with another Kansas case: that of a black female toddler who’d been beaten to death, then buried in a fencerow near Leavenworth. The person who killed her undoubtedly figured she’d be unlikely to be plowed up if she were buried among the osage oranges that serve as fence posts and windbreaks between farm fields. However, only a year or so after the girl was killed, the small farm where she was buried was sold and incorporated into a larger farm, so the windbreak was cut down and a bulldozer unearthed her remains — a mix of freshly fractured bones, partially healed bones, and fully healed bones: heartrending evidence of a brief life filled with bone-breaking abuse. As a further point of comparison, I brought in a third set of bones, belonging to a seventeen-year-old white female. This girl was from Tennessee, not Kansas, but she was the same race as Lizabeth Wilson, and she was closer to Liz’s age.
When Doug and I scanned the Tennessee teenager’s bones with the UV lamp, they all fluoresced a pale green. When we played the lamp over the Leavenworth toddler’s bones, they shone a yellowish-purple. And when we trained the light on the bones from Lenexa, every one of them glowed the same deep purple. “It is our conclusion,” I wrote in the report I sent Dr. Bridgens, “that the fourteen bones are all from the same individual.” All from Lizabeth Wilson.
Twenty-eight years passed, and no one was ever charged with Liz’s murder. Then, in early 2004, I received a flurry of calls from Senior Special Agent Brad Cordts of the Kansas Bureau of Investigation. The KBI had gotten a tip about the identity of her killer, and was about to make an arrest. They had a serious problem, though: during the nearly three decades that had elapsed since Lizabeth’s bones were found and identified, Dr. Bridgens had died and the KBI wasn’t sure where the bone had ended up. Brad wondered if I might have retained the bones at UT; unfortunately, I’d sent them back to Dr. Bridgens, according to the return receipt in my file, and he’d received them on February 7, 1975. I did have one piece of encouraging news for the KBI agent, though: my file included a copy of a cranial X-ray taken at UT Medical Center, while the bones were in my custody. As the last living link in the chain of skeletal evidence, I was the only person who could testify with direct authority that the remains had been positively identified as Liz’s.
On September 23, 2004, I stepped off a plane in Kansas City and got into a black Lincoln Town Car that whisked me to the Johnson County courthouse in Olathe, Kansas, where I’d testified in 1971 in the case of two-year-old Lisa Silvers, after her uncle was charged with her murder. There I met with Brad Cortds, the senior KBI agent. Brad brought several items with him to the meeting: my original report from 1975; the postmortem X-ray of Lizabeth Wilson’s skull; and — last but far from least — a box containing fifteen bones: the fourteen Doug Owsley and I had studied under the black light in a lab long ago, plus a fifteenth bone — a right femur — found in a hay bale a year or two after the first batch turned up. The bones had never actually been lost, as the KBI briefly feared; instead they’d been returned to the family and buried in a grave in Iowa, from which they’d recently been exhumed during preparations for the trial.
The man on trial for Lizabeth Wilson’s murder was named John Henry Horton; at the time of Liz’s disappearance, he was the twenty-six-year-old janitor at Shawnee Mission East High School, the area where she was last seen. According to news reports, the police and KBI had long suspected Horton, but they lacked enough evidence to charge him. That finally changed in early 2003, when a woman came forward and told investigators that when she was fourteen, Horton drugged her with chloroform and sexually molested her. One theory of the crime in Liz’s death held that Horton tried the same tactic with her, but gave her a lethal overdose of the drug.
The day after I arrived and met with Agent Cordts, I was called to take the stand in John Henry Horton’s murder trial. After the bailiff swore me in, Assistant District Attorney Rick Guinn led me through a series of questions designed to help the jury understand what forensic anthropology is, and what sort of qualifications I have to testify in court. Then he asked me to describe how I examined the bones back in 1975 and determined that they were all from the same young female. Finally he asked if I could tell whether the bones I’d looked at the day before were the same bones I’d studied nearly thirty years before. “They are the same bones,” I answered. “Fortunately, I did a pretty good job of the record…. The fourteen bones are numbered, or I had numbered them, the sides and what was there, and we put them in anatomical order, and they all matched.” I also described the cranial X-ray I’d taken in 1975, and explained how the air cavities that showed up in the mastoid process (the prominent bony areas just behind the ears) in the 1975 X-ray matched the air cavities in a new X-ray taken after the bones were exhumed.