Imperfect Justice_ Prosecuting Casey Anthony - Jeff Ashton [50]
The precise meaning of that sentence has been the subject of fierce debate over the last ninety years, and you could write an extremely boring book exploring all of its nuances. Simply put, it means this: the court will admit new science only if it has a firm foundation in established science.
In the Andrews case, the Frye hearing to determine the admissibility of our DNA evidence was ruled in our favor. After we successfully argued the Frye hearing, Tim Berry and I tried the case; I presented almost all the evidence and made the closing arguments. The jury found Andrews guilty of rape and other charges.
The process used for that DNA analysis was very primitive, and about four or five years later a much better process was developed that could get far more accurate results using much smaller amounts of DNA. The probability numbers back then for whether the DNA actually came from a particular individual were one in a hundred thousand. With today’s technology, the results are closer to one in a quadrillion, which would include just about every human being who had ever lived. In 2004, Andrews asked to be retested, claiming that the DNA results in 1988 were inconclusive. The state complied with his request, and a subsequent DNA test was still a match. Tommy Lee Andrew is serving a combined sentence of sixty-six years for the two rapes.
IT’S BEEN ACCEPTED FOR A long time that all scientific advancement comes from those with vision standing on the shoulders of those who came before them. It’s simply a matter of taking something that already exists and using it in a new way. The full-on nerd part of my personality finds this fascinating.
The more Dr. Vass and I shared information about our backgrounds and interests, the more I was able to convince him that this was a case that demanded his testimony as an expert witness. We talked about every aspect of his work—what inspired him, what techniques he borrowed from other disciplines, and how he came to his conclusions. We discussed the process of publication in scientific journals and the responses of his colleagues in the field. In the short time that I’d been researching odor for this case, one of the difficulties I’d found was that there were very few people who worked in this field. However, I was lucky to have one of the few pioneers on my side.
Reassuring as that was, there were still drawbacks. Dr. Vass’s field of study, odor mortis, or the smell of death, was more complex than DNA, and I knew from that first phone call that the forensics would be difficult. The main challenges in trying to collect a forensic sample of an odor are threefold. First, how do you capture the odor in a pristine form? The moment you expose a sample of air to room air, the concentration of the compounds that make up the odor are diluted. Second, further complicating the process is that once the ambient air mixes with the odor, how do you know that the compounds you find come from the sample and not the ambient air? Third, you need to establish that the compounds you find are being released from something that is still there and not an odor left behind by something that has been removed.
To help answer some of these questions about sample odor collection from the Pontiac, the crime scene supervisor for the Orange County Sheriff’s Office, Mike Vincent, went to Dr. Michael Sigman, a former colleague of Dr. Vass at Oak Ridge. Sigman