RECAP: Preliminary Decompositional Event Report part 4

Air sampling summary:
Out of 24 compounds detected in the Florida trunk sample which did not overlap with known or possible gasoline constituents, 16 (67 %) known to be associated with human decompositional events were detected in the odor signature from the Florida trunk carpet sample whose source could not be potentially linked to any of the controls which were analyzed. These included 2-methyl furan, acetic acid methyl ester, butanoic acid methyl ester, carbon disulfide, carbon tetrachloride, chloroethane, chloroform, chloromethane, decanal, dichloroethene, dichloromethane, dimethyl trisulfide, dimethyl disulfide, hexanol, methanethiol and trichloroethene. Of these 16 compounds, seven were significant human decomposition chemicals listed in the database.
Only five of these seven compounds are being used to draw conclusions about the possibility of a decompositional event occurring. Decanal and trichloroethene were dropped from this list because they were only detected in trace amounts.

These five compounds are:
Carbon disulfide appears very early in human decomposition (<100 ADDsa) appears in both aerobic and anaerobic decomposition
Carbon tetrachloride appears very early in human decomposition (<100 ADDs) appears in both aerobic and anaerobic decomposition potentially a human specific marker (not seen in select animal remains)
Chloroform appears very early in human decomposition (<100 ADDs) primarily detected in deprived oxygen (anaerobic) decompositions
Dimethyl trisulfide appears very early in human decomposition (<100 ADDs) appears in both aerobic and anaerobic decomposition
Dimethyl disulfide appears very early in human decomposition (<100 ADDs) appears in both aerobic and anaerobic decomposition a ADD – accumulated degree day (an accumulation of average daily temperatures)
This assumes that all the control samples contributed equally to the odor signature in the trunk (which is unlikely) and does not take into account that numerous compounds in the controls were detected in trace amounts and that some were potentially highly concentrated by the TST collection procedure. [For example, fluorinated compounds were detected in the Forensics Unit Garage, but were not detected in the Florida vehicle trunk sample potentially indicating very little, if any, contribution of the garage air to the trunk signature].

TSTs collected from the Florida trunk were analyzed even though the trunk liner had been removed and the odor would not have been representative of what was originally present at the time of vehicle discovery. Even with the liner removed, sulfur containing compounds such as carbon disulfide, carbon tetrachloride, chloroform and dimethyl disulfide were still detectable in trace amounts. The trunk was the only location where all these types of compounds were detected.

Common fluorinated compounds usually associated with human decomposition were not detected in the Florida trunk sample. It is possible, although this has not been studied, that a 3 year-old child may not have had sufficient time (many years) to ingest enough fluorinated compounds for them to be incorporated into tissue and then to appear in the decompositional breakdown of soft tissue and bone. Additionally, several of the identified compounds are typically associated with anaerobic decomposition. While the actual significance of this not known, it indicates that any type of decompositional event that might have been associated with the odor in the trunk of the car could have occurred under deprived oxygen conditions.