Free Behind the Yellow Tape: On the Road With Some of America's Hardest Working Crime Scene Investigators by Jarrett Hallcox, Amy Welch

kept. The two tarps were still evidence at the time, but the case had just gone through all of its appeals, and the defense had failed. Snow’s fate was sealed. The sentence would stand for eternity, and the evidence could now be opened. “I then took the tarps and went over them inch by inch with a fingerprint loupe looking for ridge detail”—the fine lines of a fingerprint—Carnahan explained as he and Cochran located the tarps still sealed in large brown paper evidence bags. Detective Carnahan had gone over the tarps closely, front and back, using a Sharpie to circle areas that had at least some ridge detail. Then he hit those areas with a fluorescent dye stain to enhance the prints’ visibility so he could use a forensic light source to bring out more detail. And there it was—a nearly complete left thumbprint. “The guys who run AFIS [Automated Fingerprint Identification System—the searchable database of fingerprinted criminals] laughed when they heard I was trying to develop a print off a tarp,” Carnahan told us as we stood watching him and Cochran lay the tarp out on the floor of the police department garage, rehydrating the print by spraying it with the dye stain Ardrox so we could see it better. With the hum of the light source in the background, Carnahan and Cochran jumped around the tarp like elves, looking for just the right angle to view the print in detail. Though time and folding had changed the clarity somewhat, there the print was, right in front of us, about five feet up from a deep maroon-colored stain: the color of dried postmortem blood—Patricia Volpenhein’s blood. It was eerie to see the evidence up close and personal, and amazing that Carnahan had ever found the print in the first place.

    Brian Cochran and Tim Carnahan examining the tarp for fingerprint evidence.
HALLCOX & WELCH, LLC
     
    With the print developed, Carnahan needed a good picture to send to the guys at AFIS for comparison in the nationwide database, in order to see if there was a match. The first picture had a little bit of a wave from the tarp, which made it difficult for the guys to put into AFIS. But the next picture was perfect, and within hours a hit popped up on the screen—John T. Snow.

    Latent fingerprint that was found on the tarp. The print
matched John Snow’s.
PHOTO BY TIM CARNAHAN, OFFICE OF THE COMMONWEALTH’S ATTORNEY,
54TH JUDICIAL CIRCUIT
    Forgetting to wear his gloves was Snow’s first mistake—and leaving one behind would be his last. In order for a murder to be a capital offense in most states, meaning a death penalty case, there needs to be more than just murder for murder’s sake. It seems ridiculous, but there must be extenuating circumstances, such as multiple homicides, extraordinary violence, or rape. Premeditation alone won’t necessarily do it (and in this instance, the knowledge of premeditation only came out of Snow’s interview after his plea). This gave Snow’s attorneys some hope that they might be able to mitigate Snow’s punishment and avoid the death penalty. But Carnahan wasn’t finished with the evidence. Almost as an afterthought, Carnahan processed the glove that had also been found at the scene. It was a cotton knit style of glove and, unlike a latex glove, one that would be impossible to retrieve prints from. However, given the ever-increasing sensitivity of DNA testing, Carnahan decided to send the glove to the lab to see if any epithelial cells could be recovered. Knowing it was a long shot, he also sent the rape kit that had been done on Volpenhein, just in case there was anything to compare the evidence to. And there was. John Snow’s skin cells were found not only on the interior of the gloves but also on Volpenhein. With that evidence, the case became a capital murder trial because it appeared now that John Snow might have raped Patricia Volpenhein. When confronted with that evidence, Snow went crazy, showing the only emotion he ever displayed over Volpenhein