Imperfect Justice: Prosecuting Casey Anthony (20 page)

In order to reassure him that I was up to the task of shepherding him through this process, I talked to him about my prosecution of the first DNA case, the Tommy Lee Andrews trial. In a sense, my use of DNA started with an NBC news story about a man named Colin Pitchfork in England. Two girls from two small towns in the county of Leicestershire had been raped and murdered in a similar fashion. Investigators employed a new technology developed by British geneticist Alec Jeffreys to track the killer down. They used DNA fingerprinting to screen the men in one of the small towns in particular. The idea was that someone’s blood held a unique DNA that, when matched to the blood at the crime scene, could determine the killer beyond a reasonable doubt. All the men in the village were asked to submit blood samples. Colin Pitchfork paid someone two hundred pounds to donate on his behalf. Eventually, his stand-in gave him up, and his DNA proved to be the match the authorities had been looking for.

For obvious reasons, I thought the Pitchfork case could be very applicable to my work as a prosecutor. At that point in my career, I had been involved in cases where the traditional study of human fluids—blood typing and protein antigen typing—was occasionally being used, but the ability of science to characterize specific blood or semen stains from a crime was very, very limited. If you were able to get a number that limited the possibilities to 10 percent of the population, you were ecstatic. That was about as much information as blood was going to give you. After hearing about the case in England, I thought it was clear that there was a lot more we could learn from blood. But though this technology would obviously be of use in the United States, there was no lab in the United States that did it, so I just filed it away as an interesting bit of trivia.

A year or so later, in 1987, I was flipping through a newspaper put out by the Florida Bar Association when I came across an advertisement that caught my attention. The ad featured a picture of a baby with a caption that read: “He is wearing his father’s genes.” The ad was for a lab in New York that was doing paternity testing. I remembered the Pitchfork story in England and wondered if this was the same science, even though used in this case to determine paternity. I contacted someone at the lab in New York to find out if it was the same kind of work Jeffreys was doing. I asked the lab’s director if they did criminal cases, and he told me they were just starting to do forensics testing.

At the time I didn’t have any rape cases, but I went to Tim Berry, one of the state’s sex crimes prosecutors, and asked if he had any cases with semen that could be tested. Indeed he did—Tommy Lee Andrews. Andrews had been charged in six cases of rape, but the witness IDs were not great in any of them. Andrews would break into the home of a young woman, put a pillow over her face, rape her, and rob her. At least one of the women had picked him out of a photo lineup from having seen him the moment before he grabbed her, but the light had not been very good. The other victims had not seen him.

We had six samples from six cases, along with a sample from the defendant. The lab in New York was able to get results in two of the six, and matched them to the defendant. We added the names of the lab personnel who had done the testing to the witness list. Nobody else in the United States had ever used this kind of evidence in a case, but even so, I don’t think we fully realized how earth-shattering this DNA evidence would be for prosecutors and defense attorneys alike. The bottom line was that we thought it was cool, and we were excited to be the ones giving it a shot.

We decided to get an expert not affiliated with the lab to testify, choosing David Housman, a molecular biologist and a professor at MIT, to explain the science behind what we’d done. Fortunately for us, the judge who happened to be assigned to the Andrews case, Judge Rom Powell, had experience in judging trials that hinged upon cutting-edge forensic evidence. He had been the first to rule on a case that was used a new science called voice print identification. We had a Frye hearing, which is a specialized process to determine whether a new scientific tool is based on generally accepted, established scientific principles.

“Frye hearing” comes from a 1923 case in which a fellow by the name of James Alphonso Frye was being tried for a murder in Washington, D.C. His lawyer wanted to present to the jury evidence from an expert who claimed that the truth could be determined by looking at changes in the blood pressure of an individual during an interview, an early version of the lie detector. The trial judge ruled that the evidence was not admissible, and the appeals court agreed. Those decisions contained a single sentence that to this day determines the admissibility of scientific evidence in Florida and most jurisdictions in the United States: “the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.”

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.

I
T’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 was with the National Center for Forensic Science at the University of Central Florida. The first attempt to collect the odor sounded simple enough: open the trunk just enough to insert a small hose and, using a large syringe, pull out a volume of air and then expel it into a bag. But that method failed to collect a sufficient sample of air to get any reliable result.

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 that was also perhaps the most disturbing. The results of his tests identified a high level of chloroform in the specimen of carpet from the Pontiac’s trunk. The levels were so high, in fact, that chloroform was the most prevalent compound discovered. Dr. Vass explained to me: while chloroform might be produced by human decomposition, it would be in extremely small amounts. The amounts revealed in his test were thousands of time greater than he had ever seen from a decomposing body. In his opinion, the chloroform had another source, although he could not establish it. This discovery of chloroform in the trunk was later confirmed in testing performed by the FBI.

The presence of chloroform in the trunk sample was a surprise to all of us. Chloroform had been known to be used as an anesthetizer to knock victims out, and it wasn’t something you could get at the local drugstore. Since it wasn’t a commonly abused product, Detective Melich thought it might be worth a shot to check the Anthonys’ computers to see if anyone had tried to buy it online.

Detective Sandra Cawn, an experienced computer forensics investigator with the Orange County Sheriff’s Office, had already been mining the Anthonys’ computers for any leads that might help us learn the whereabouts of Zanny. Melich asked if she could also check for searches involving the word “chloroform.” Detective Cawn first searched the hard drive of the laptop that Casey had been using at Tony’s and found nothing. She then turned her attention to the desktop computer used at the Anthony home.

Her initial inspection of the active files came up empty. She then looked at the unallocated space of the hard drive.  As it was explained to us, when you permanently delete something from your computer, that digital information gets transferred to another space on the hard drive, where it can then be overwritten with new information.  This computer version of limbo is called “unallocated space.” Even though we think the file is erased from our computer, in fact it may still be there. Over time, all or portions of the information will be truly erased, as new information takes its place. Until that happens, though, a computer forensics investigator armed with the right software can mine that data.