Soil bulb mites as trace evidence for the location of buried money

This study reports for the first time the use of soil micro-invertebrates, mites, as trace evidence to localise buried objects such as money. The case relates to a crime in Germany, where a large sum of banknotes had been hidden in an unknown location, likely abroad. In 2016, part of the money (approx. €500,000 in €500 value notes) was confiscated by the police. After analysis in the forensic lab, it was discovered that the notes were covered with small particles of a sort of debris, later identified as specimens of Rhizoglyphus howensis Manson, a non-European, nor Mediterranean species of root or bulb mites (Acaridae: Rhizoglyphinae). The restricted biogeographic distribution of R. howensis, originated in unspoiled forest soil in the Australasian region, limited the search for the money to the areas visited by the perpetrators during their trips to the region. Rhizoglyphus howensis biology provided further clues on the whereabouts of the banknotes, as they are specialist plant feeders, exclusively feeding on seeds of palm trees and on roots of Quercus patula in the Australasian region. This report aims to highlight the importance of the correct identification of the microscopic organisms associated with a crime scene and the immediate retrieval of micro-invertebrate trace evidence. This is the first record of R. howensis from Europe, and from banknotes.