Procambarus Clarkii, the “Louisiana crawfish”, scavenging on a human corpse. Case report and experimental study

Aim of the study. This study provides macroscopic and histological data on post-mortem skin and inner lesions produced by Procabarus Clarkii (PC), also known as the “Lousiana crawfish”, on submerged human bodies. A comprehensive documentation, including photos and video-clips of the scavenging activity of PC on human tissues will be presented during the poster session. Introduction. The scavenging injuries on corpses in inland waters are usually related to rat and fish activity, and only a few cases of scavenging by crustaceans have been reported in the forensic literature. The red-swamp crayfish (PC) is endemic in North and South-East America and was originally introduced in Europe for commercial reasons. PC adults are red, orange or reddish brown and can reach the length of 15 cm. Feed consists of plants, detritus or animal food; cannibalistic behaviour has also been observed. To the best of our knowledge this is the first study on the scavenging effects of PC on death human bodies. Case report. On September, the corpse of a man who was missing since 18 days was found supine, floating on an irrigation ditch (water temperature: 24º C) in the countryside of Padova, Italy. On the scene, 7 red shrimps (about 10 cm in length) were identified near the body. Autopsy was performed on the same day the body was found. The external inspection identified advanced autolysis and putrefaction, associated with typical signs of a prolonged submersion time, multiple substance defects (including minute circular lesions on the right axilla), complete absence of the thoracic and abdominal viscera and the presence of three red shrimps inside the abdomen. Drowning was identified as the most probable cause of death. Experimental study. One shrimp, captured during the autopsy and identified as PC, was put inside a fresh water aquarium with a squared piece of fresh human skin (side: 4 cm). The fatty tissue underlying the skin was suddenly attacked and eaten by the crayfish. The skin, however, was ignored. The piece of skin was removed from the water and another one was wrapped with plastic in order to expose only a circular skin area of 1,5 cm2. Seven days later, a minute circular skin lesion (diameter 0,5 cm) with irregular margins and non-vital characteristics was observed. Discussion. Direct evidence of the scavenging activity of PC on human remains was achieved by our simple experimental study. PC, attacking suddenly the fat tissue underlying the skin, displayed a preference for nourishing tissues (i.e. fat vs skin). On the other hand, the skin was attacked from the shrimp only after one week of submersion, when transformative changes with detachment of the superficial layers were evident. We can suppose that the shrimp, because of the degradation of the skin, was able to sense the underlying fat tissue, thus attacking the rotten human skin. The resulting lesion was very similar to the minute substance defects detected on the right axilla in the reported case. The access of PC into the body cavities probably occurred across a substance defect of the abdominal wall, produced by rodents or fishes. On the other side, shrimps have demonstrated the ability to perforate the skin or to enter the body from the oro-nasal cavity; therefore, especially in cases in which they are the unique scavengers on the scene, their faculty to enter the thoracic or abdominal cavities should be taken into consideration. In our case, due to the prolonged submersion time (18 days) and the presence of several crawfishes at death scene investigation a relevant role of PC in devouring the submerged body can be hypothesized. Conclusions. The reported case and the experimental data obtained suggest a relevant post-mortem scavenging capability of Procabarus Clarkii (PC) on submerged human corpses.