Examination of postmortem animal interference to human remains using cross-species multiplex PCR

Abstract

Postmortem animal interference may be confused at first sight with injuries of vital origin, thus arousing suspicion of external violence preceding death. A reliable classification of the origin of such doubtful injuries is of crucial importance, a fact that is especially true for the investigation of suspected homicide and/or mammade body mutilation after death. In forensic pathology, the identification of injuries as caused by animals postmortem and the classification of a particular species as responsible for a specific injury pattern under question is usually done by forensic pathologists with vast practical experience and special knowledge of the appearance and morphology of tooth marks of carnivores and rodents, respectively. However, a molecular biological investigation of such wounds could provide genetic evidence that an injury pattern present on a corpse was truly caused postmortem by animal interference and thus support the pathologist's expertise. For this purpose, we developed a panel of small species-specific short-tandem repeat systems (<150 bp) for animals typically involved in postmortem scavenging of human remains, such as dogs and cats as well as wild-living rodents (mice and rats) having possible access to death scenes inside apartments or buildings. A specific and sensitive cross-species multiplex polymerase chain reaction was then established including the species-specific animal markers, thus enabling the genetic identification of wounds caused postmortem by different animals on human remains.