Comisaría General de Policía Científica

Trabajo realizado por los expertos en Entomología Forense de la Sección de Antropología Forense de la Comisaría General de Policía Científica.

Publicamos el trabajo realizado por los expertos en Entomología Forense de la Sección de Antropología Forense de la Comisaría General de Policía Científica, que se presentará en el libro "proceedings of the meeting" con ocasión de la "Reunión Anual de la EAFE (Asociación Europea para Entomólogos Forenses)", consistente en un póster y en el abstract. Dicha reunión tendrá lugar este año en Londres, los días 28 a 30 de Marzo, y asistirán los entomólogos forenses más prestigiosos de Europa, Estados Unidos, Sudáfrica, Australia y Hawai( Universidad de Manoa, dedicados fundamentalmente a la Entomotoxicología).

A CASE DESCRIPTION

García Rojo A., Honorato L.

Sección de Antropología, Comisaría General de Policía Científica. Madrid. Spain

INTRODUCTION: The decomposed remains of an unidentified man about forty years old were discovered hanging from a tree in a forested area in Aranda de Duero (north-west of Spain). The remains were badly decomposed. The death body was with shading from direct sunlight for most of the day. The Judicial Authority asked for the estimation of the time of death; in order to focus the investigation.

MATERIAL AND METHODS: Insects were collected from the remains during autopsy by investigators on September 23, 2002, after remains had been stored in a refrigeration cooler set at 2ºC from September 20th to the 23rd.
The insects collected, adults specimens of Coleoptera and Diptera larvae in different stages, were recovered in the body (head, natural orifices, trunk and extremities). Afterwards, in our lab belonging to the Department of Anthropology of the General Department for Forensic Science of the Spanish Police, Diptera larvae were measured and identified (Rognes K.,1991) and Coleoptera adults were also identified (Plata Negrache P. 1971, Outerelo R. et al. 1985).
Temperature data were obtained from the local weather station placed 2 kms far from the crime scene and at approximately the same elevation. This ocurrence provides greater accuracy in the estimation of the PMI.

RESULTS: Arthropod identification: 3rd. instar larvae Diptera:Calliphoridae; Calliphora vicina R-D, 2nd. instar larvae Diptera:Calliphoridae; Chrysomyia albiceps W, adults Coleoptera: Staphylinidae; Philonthus curruscus, adults Coleoptera: Dermestidae; Dermestes frischii K.
The degree days (DD) and accumulated degree day (ADD) were calculated. The two different species of Calliphoridae present lower limit temperature thresholds used for Chrysomyia albiceps with the base of 10ºC and Calliphora vicina with a base of 6ºC.
The oldest specimens recovered from the remains during autopsy was Calliphora vicina (3rd instard). Rearing and developmental data from a study by Marchenko on C. albiceps and by Byrd on C.rufifacies (a close sister of C.albiceps) and Calliphora vicina were used.
The presence of 3rd instar larvae of the group Diptera:Calliphoridae Calliphora vicina and 2nd instar larvae of Chrysomyia albiceps , both being consistent with the time of year the body was found. These two species of blow flies are common blow flies in this area of Europe during the summer and early autumn.
Between 30 and 40 ADDs (as calculated from the climatological data) are required for C. albiceps to reach into the middle of the 2nd instar, and between 100 and 160 ADDs to reach into the middle of the 3rd instar larvae for Calliphora vicina.

CONCLUSIONS: Based upon insect development of the oldest specimens present (3rd instar larvae of Diptera: Calliphoridae; Calliphora vicina), the prevailing temperatures for the period, and the environment where the remains were recovered (hanging in a tree in shade), the remains would have been exposed to colonization by C. vicina from the afternoon to early evening (prior to sunset) of September 12, 2002 to as early as late morning of September 10, 2002. This is provided the insects recovered are the oldest insects maturing on the remains. Death of the individual would have preceded the insect colonization.

Acknowlegments: We thank the very useful help from Dr. Haskell in order to calculate the PMI and elaborate this paper.

REFERENCES:

  • 1997, Byrd J.H.; Butler J.F.- "Effects of temperature on Chrysomyia rufifacies (Diptera:Calliphoridae) Development". Journal Medical Entomology. 34(3);353-358.
  • 2001, Marchenko, M.I.- "Medicolegal relevance of cadaver entomofauna for the determination of the time of death". Forensic Science International. 120(2001);89-109.
  • 1971, Plata Negrache P.- "Revisión de la familia Dermestidae Latr. En la Península Ibérica e Islas Baleares"; pp:1-530;UCM (comunicación inédita).
  • 1991, Rognes, K.- "Blowflies (Diptera:Calliphoridae) of Fennoscandia and Denmark. Fauna Entomologica Scandinavica". Vol. 24. E.J.Brill. Scandinavian Science Press Ltd.
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