There are criminal cases that no frequently used evidence, for example,
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 boyfriend'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 fragments were
amplified and sequenced on a next generation sequencing platform. Of the
2980 ZOTUs in total from the 12 samples, 1495 ZOTUs were identified to
species, genera or families based on the existing public database. The
feast analysis based on either taxa or taxa plus abundance data
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.