Holistic approach in the forensic analysis of geological trace evidence: as Forensic Botanists and Geologists may help judicial investigations

In the 1978, Gianni Lombardi and Valerio Giacomini, two Italian experts in forensic geology and botany, respectively, were involved by the judicial authority for analysing the sands and plant remains found in the clothing and moccasins of the honorable Aldo Moro, kidnapped and killed by terrorists. Experts had to determine the site where this material transfer occurred.

As demonstrated by the analyses carried out by these experts, plant taxonomists can give useful information in forensic analyses especially for events occurring outdoor. Small plant traces spread in quantity, like pollens, spores, thorns, seeds and small fruits, may easily transfer to the clothing and footwear of people or to the same human body, moving outdoor in the countryside.

In 2020, 42 years later, the authors of this research were involved by the judicial systems to reconstruct the events related to the disappearance of two persons, in the Sicilian countryside, found cadavers a few days after in a site near the last sighting of them.

The research focused on the morphological description of thorns, other pointed structures, and seeds produced by plants thriving in the scene of events. For simplicity, it was chosen to use the generic term "thorns" to indicate pointed plant structures, although aware that the term "prickle" should have been used for epidermal structures, “thorns” strictly for stem-derived structures, and "spines" for other structures derived from leaves, petioles or stipules.

A photographic atlas of thorns and seeds was produced with the species found in the scene of the events. A comprehensive description of plants as they appeared in situ as well as of their thorny appendices was made, and explanatory pictures were captured, both in situ and under the stereoscopic microscope in the laboratory. The extensive biometric analysis made on thorns and seeds of all collected species in the scene of events was recorded.

Soil traces and microtraces of forensic samples of unknown origin (from the victims’ bodies and their belongings) were investigated for the presence of thorns or thorn fragments and seeds, which were then compared with those recorded in the atlas.

The organic component (vegetal elements) of the forensic geological traces from victims and their belongings was predominant in quantity over the inorganic one.

Comparative observations allowed to identify hundreds of thorns and thorn fragments and several hundreds of seeds found on the clothes and footwear of both victims, as plants thriving in the area under investigations. Basing on the punctual distribution of individual plants, the analysis of thorn traces and seeds was useful, together with geological analyses on sands and clay minerals, in reconstructing the path of the victims in the hours immediately preceding their death and, therefore, provided valuable information to the investigating authorities.