Determination of a criminal suspect using environmental plant DNA metabarcoding technology

There are criminal cases that no frequently used evidence, for example, human DNAs from the criminal, is available. Such cases usually are unresolvable. With the advent of DNA metabarcoding, evidences are mined from environmental DNA and such cases become resolvable. This study reports how a criminal suspect was determined by environmental plant DNA metabarcoding technology. A girl was killed in a rural wet area in China without a witness or video record. Pants with dried mud was found from one of her classmate's house. The mud was removed from the pants and 11 more mud or soil samples surrounding murder scene were collected. DNA was extracted from the soil. Chloroplast rbcL gene were amplified and sequenced on a next generation sequencing platform. After bioinformatics analysis, ZOTU composition of 12 samples demonstrated that the mud on the suspect's pants was from the criminal scene. The suspect finally made a clean breast of his crime. This case implies that plant DNA in the environment soil is a new source of evidence in determination of suspects using DNA metabarcoding technology and has high potentials of extensive applications in criminal cases.