ESTIMATION OF POST MORTEM INTERVAL THROUGH FLY LIFE CYCLE ON WHISTAR RATS IN MEDAN

Muhammad Fernando Manik, Amri Amir, Asan Petrus

Master in Clinical Medicine Forensic Medicine and Medicolegal Program Faculty of Medicine, University of North Sumatra

Background : In deaths related to criminal cases, one of the most important things is determining post mortem interval. Estimation of PMI can be determined from changes that occur in dead bodies such as fall in body temperature, body bruising, post mortem rigidity and putrifaction. After the process of putrifaction, the estimation of PMI is rather difficult. In such case, estimation of PMI using the life cycle of a fly which begins  laying eggs, developing into instar I, II, III, prepupa, pupa and becoming flies.

Method: Observational research using 20 healthy male whistar rats aged 3-4 months with a body weight of 150-250 grams divided into 4 quadrants, having been dislocated in the cervical bone and slashed in the abdomen with 1 cm long and left to decay. When there were larvae in the sample, 5 largest larvae were taken in each sample. The collection of larvae was carried out every day at the same hour. The larvae were terminated by soaking them in 70% alcohol solution for 4 hours and then measurements of the larvae was done in the Biology Laboratory of the Faculty of Mathematics and Natural Sciences, besides that the samples were also taken and reared at the FMIPA Laboratory and identification was done by the Biologists.

Result : The development of the life cycle in quadrants 1 and 2 is almost similar to that of coastal conditions, whereas the development of the life cycle of the flies is influenced by geography, the state of temperature, the rain and humidity. Likewise with quadrants 3 and 4 which have almost similarities because these two locations but are far from the coast and close to settlements. The type of fly encountered are Chrysoma Sp and Lucilia Sp, and there is no difference in the genus of fly larvae in dead whistar rats located near the coast and far from the coastal area where this study was conducted on the type of external fly species, The largest random sampling was done.

Conclusion :. PMI estimation in the city of Medan is 12 days with the identification of the fly types encountered as follows, Chrysoma Sp dan Lucilia Sp.

 

Keywords : PMI, larvae length