Imperfect Justice_ Prosecuting Casey Anthony - Jeff Ashton [51]
Next, Dr. Sigman used the best technology available to him, placing small synthetic fibers, known by the acronym SPMI, into the trunk for a period of time. The fibers act as adhesives to compounds in the air, capturing those compounds immediately surrounding the fibers. The difficulty with this method is that it can sample only the very small volume of air that happens to pass over the fibers. Since the air in the trunk couldn’t circulate, the sampling of the air was just too limited to determine the existence of compounds in very small quantities. The test did nothing to tell us what the odor was emanating from.
Finally, Dr. Vass suggested that we cut a small sample from the stained carpet itself, seal it in a small metal can, and mail it to the Oak Ridge Lab to be tested by him. He took the carpet sample and placed it in a special bag made of a plastic designed not to react with the substances placed in it. Vass then heated the carpet to the approximate temperature that would have existed in the trunk, removed a sample of the air, and cooled it to concentrate the sample. After the cooling was complete, he ran it through a gas chromatograph/mass spectrometer, a device commonly used by scientists to break a substance into its underlying compounds. The results of all this demonstrated that the odor coming off that stain was consistent with what his research had detected coming off a decomposing human body. Equally important was that it did not match the research on decomposing animal remains.
Another smell that needed analysis was that of pizza. Ever since Casey’s arrest, there had been comments by the defense and the Anthonys in the media attributing the smell in the trunk to that of a rotting pizza. An empty pizza box had been found in the garbage bag that had been removed from the trunk while the car was at the tow yard, although there were only crumbs of pizza left. Vass wanted to know if that was possible, so he took a pizza out of his freezer and let it rot in his backyard for a week, then tested the odor. The two smells didn’t match.
Vass offered to test another possibility that had received speculation in the media: that the odor was from a road-killed squirrel stuck to the car’s undercarriage. This is what Casey had alleged in a couple of her texts to Amy Huizenger during the thirty-one days that Caylee was missing. I told him that testing a squirrel would be great, but I didn’t want him running out and killing any innocent squirrels. He laughed and expressed confidence that in rural Tennessee he’d be able to find some roadkill to test, which he did. The dead squirrel didn’t match the odor from the car either.
In addition to the pure science he had applied to the problem, he had another tool at his disposal: his nose. Having studied odors as much as he had, he was uniquely qualified to identify them and the differences between them. The first time he opened the paint can containing the carpet sample, he told me he jumped back two feet, the smell was so unmistakable and strong. He was certain it was the smell of death.
His testing of the carpet fibers revealed fatty acids and inorganic elements in concentrations consistent with human decomposition. In addition, he tested a suspicious greasy substance on a paper towel that had also been in the garbage bag from the trunk. He found that the substance on the paper towel was chemically identical to another by-product of decomposition called adipocere, or “grave wax.” None of these findings alone was an irrefutable sign of the presence of a dead body, but the combination of them all was starting to paint a clearer forensic picture.
Of Vass’s findings, there was one more piece of particular interest