MURDER MYSTERY IN MIDDLE TENNESSEE: PROVENANCE ANALYSIS OF NATURAL SEDIMENT RECOVERED FROM HUMAN REMAINS AND ITS ROLE IN A HOMICIDE INVESTIGATION AND CRIMINAL TRIAL

A human mandible from an anonymous mail package was the central piece of physical evidence in a 1996 homicide in the Clarksville, TN area. Several hundred natural sediment grains were recovered from the mandible. Two previously mailed anonymous letters received by police indicated the victim’s remains could be found in a creek in the Gallatin, TN area, some 70 km away from the victim’s last known location in Clarksville. Local investigators asked for assistance in determining the origin and location of the sediment.

Sediment from the mandible consisted of grains of siltstone, chert, fossil biogenic material, and quartz ranging in size from 0.06 to 4.5 mm in diameter. Lithologic and textural characteristics suggest the sediment was locally derived from Mississippian through Ordovician sedimentary rock formations found in the Central Basin of Tennessee. The composition is similar to stream sediment from the Gallatin region. In particular, gastropod fossils, dolomitic siltstone, and phosphatic siltstone grains are similar to those found in the creeks of that area.

Comparison of the mandible samples with stream sediment from the Clarksville area exhibited consistent differences in rock composition and fossil biogenic content. These differences indicate that it is highly unlikely the sediment recovered from the mandible originated from rock formations in the Clarksville area which are entirely Mississippian in age.

The analysis established the mandible sediment was distinctive enough to serve as a forensic tool and was used to obtain a search warrant of a suspect’s residence and to better define search areas to locate the remains of the victim. During the criminal trial, prosecutors used the sediment analysis to establish that the original location of the victim’s remains was consistent with the location given in the two anonymous letters. Additionally, since no other remains of the victim were found, the provenance of the mandible sediment helped prosecutors establish the victim’s death was a homicide.