The call came into the Orlando, Florida 911 operator on July 15, 2008 from Cindy Anthony who had earlier reported her granddaughter missing, "I found my daughter's car today, and it smells like there's been a dead body in the damn car”. Over the next few weeks the mystery of what happened to little three year old Caylee Anthony would deepen as investigators tried to sort out the details of the convoluted story that the child's mother and the police's chief suspect, Casey Anthony, would tell about the disappearance of her beautiful, little daughter. Later the grandmother would change her story and say it was a pizza that had been in the trunk for two weeks and had maggots on it that had caused the smell.
What's in the Trunk
Orlando Police investigators said it was definitely the smell of human decomposition they found when they investigated the car both at the home and later at the police impound center. The smell of a decomposing human body is an overwhelmingly putrid smell that can not be mistaken or mimicked by any other smell. That smell is, like the scream of a mountain lion in the dark mountain woods, one of those things you never forget. A smell that makes even the most seasoned investigators sick at times. In addition, two trained cadaver-dogs hit on the car trunk area when brought into the investigation.
Analyzing the Evidence
Samples of air from the car trunk, samples of carpet, and dirt samples from the trunk floor were sent to the laboratory of Dr. Arpad Vass at Oak Ridge National Laboratory, Oak Ridge, Tennessee for odor analysis of the organic chemicals in the samples. Dr. Vass' laboratory is world recognized as a leader in the analysis of chemical components found upon decomposition of human and animal bodies. His lab is used by the FBI and works in conjunction with investigators at the Body Farm in Knoxville. Tennessee. The same body farm which is devoted to the study of all aspects of the decomposition of the human body is operated by the University of Tennessee.
Samples of air and carpet were prepared for analysis by gas chromatography/mass spectroscopy analysis. Blank samples of air from around the car, as well as, carpet removed from similar make of car were used to establish background blanks. In addition, a pizza, with mushrooms and pepperoni, was also allowed to decompose and samples were taken from it for analysis. It should be noted that no maggots appeared on the decaying pizza during the decomposition period.
All samples were analyzed and the results compared against a library of over 192,000 known, unique chemical compounds. In addition, the results were compared to chemicals contained in the Decompositional Odor Analysis Database (DOA) which contains 424 uniquely identifiable volatile chemicals from there various stages of human decomposition. Compounding the forensic analysis of a body in a car trunk is the fact that gasoline and its many volatile breakdown products are always present in a car's trunk air and carpet. In addition, cleaners, engine additives, waxes etc may be present in a car and leave behind their unique volatile chemicals. These chemicals can many times mask the results for a specific chemical odor from the decaying body.
The Critical Findings
A total of fifty-four compounds were identified in samples from the car trunk. Of them, eighty percent (43 compounds) were consistent with a decompositional event. It is common to find a number of fluorinated chemical in decaying body samples. These were no found in these samples. However, since the assimilation of these compounds in tissues of the body takes place over an interval of many years, it is likely that a three-year-old child would not have had enough time to accumulate significant amounts of these compounds in her body tissues.
Decomposition can occur under aerobic (oxygen present) or anaerobic (limited oxygen present) conditions. The pattern of volatile chemical present in a sample varies depending on whether air is present or not present. In the analysis of the Anthony's car trunk several of the chemicals identified are consistent with decomposition that occurred under anaerobic conditions. This would be consistent with a body decaying left for a number of days in a car trunk in the hot Florida sun where limited fresh air would be present. When the child's body was finally found in December of 2008 her skeletal remains were found in a black plastic trash bag. If here body was in the car trunk also in the plastic bag them the chances of decomposition by the anaerobic route would be greatly enhanced.
Some compounds revealed in the chemical profile of the air and carpet samples are compounds which are exclusively found with decomposing human bodies and not found with decomposing animal bodies. This essentially rules out the argument by the child's mother that an animal had gotten into her car trunk and died and decayed there. The final decision that the decomposition of a human body had occurred in Casey Anthony's car trunk was based on the analytical results of five specific chemicals. These compounds are all found in the very early stages of decomposition which would be consistent with the fact that the body was removed from the car trunk before the car was found.
The Conclusion
Four of the five compounds can occur with either anaerobic or aerobic decomposition. These compounds are: carbon disulfide, trimethyl trisulfide, dimethyl disulfide, and carbon tetrachloride. The fifth compound, chloroform, is primarily found in situations where the decomposition occurs in oxygen deprived or anaerobic conditions. One of the compounds, carbon tetrachloride, is considered a human specific decomposition marker and is not seen in the decomposition of animal carcasses.
Nearly all of the chemicals found in early stage decomposition were detected in the trunk samples. Compounds usually found in late stage decomposition of a body were not present in the trunk samples. This supports the notion that the body was only present in the car trunk for a relatively short period of time. Several compounds routinely found with decomposing animal remains were not present in the car trunk samples supporting the conclusion that this had been a human body and not an animal in the trunk.
This case of the tragic death of a small child demonstrates how continuing advances in forensic chemical analysis are aiding the investigators in developing clues and the prosecutors in developing effective prosecutions of criminals who commit these sort of heinous crimes.
