Forensic Indicators Research Articles

Larval identification key to necrophagous Coleoptera of medico-legal importance in the western Palaearctic.

Several necrophagous Coleoptera species are frequently collected on cadavers, may occasionally act as intermediate or paratenic hosts of parasites, as vectors of pathogens or as allergens, and can also represent major pests of preserved animal products. However, despite their medical, veterinary and economic importance, there is a lack of reliable species identification tools for the larval stages (usually the only entomological evidence associated with medicolegal investigations), thus severely limiting their potential application as forensic indicators. Here, we provide an identification key to the larvae of the necrophagous Coleoptera species which have been recorded on carrion in the western Palaearctic region, based on easily observable morphological characters. In total, we provide diagnostic characters for the reliable identification of 23 necrophagous Coleoptera species within four different families (Cleridae, Dermestidae, Nitidulidae and Silphidae). In addition to the aforementioned families, we provide diagnostic characters for the identification of the larvae of families Histeridae, Staphylinidae and Trogidae, which can also be collected on cadavers. It is expected that the present key will facilitate the identification of larval material of necrophagous Coleoptera collected either in carrion succession studies or during medicolegal investigations, in order to further advance in the potential use of this insects as forensic tools.

Flies (Diptera: Calliphoridae, Sarcophagidae, Muscidae) associated with human corpses in Alexandria, Egypt

During the period from 20 May 2000 to 8 May 2002, 15 human corpses found in different seasons and habitats in Alexandria, Egypt were investigated for insect evidence. The present study aimed to identify and record the different species of flies infesting the corpses to establish a database for the potential use of insects as forensic indicators in Alexandria. Insect collecting was performed during an autopsy at El-Esaaf Morgue, Kom El-Deka, Alexandria. All the corpses examined were enrolled in death investigations. Larvae of six fly species belonging to three families were collected from the corpses; Calliphora vicina, Chrysomya albiceps, Chrysomya megacephala, and Lucilia sericata (Calliphoridae); Sarcophaga argyrostoma (Sarcophagidae); and Muscina stabulans (Muscidae). These fly species were the initial colonizers of the corpses and, hence, are important in minimum postmortem interval estimates in Alexandria. Larvae of Calliphoridae were the most common and abundant insects, collected from 86.66% of the corpses and infested corpses in all seasons and habitats. Chr. albiceps was the most common species, invading 73.33% of the corpses of which 33.33% of infestations were found in urban, indoor situations. Outdoor infestations of corpses by this species accounted for 40%. Larvae of Chr. albiceps were collected from corpses in all seasons and were found to monopolize six corpses. Chr. megacephala, L. sericata, and S. argyrostoma were able to invade each 20% of the corpses where they acted as primary flies. S. argyrostoma was found to be a highly indicative species to corpses found in urban, indoor habitats during the warmer seasons. Three cases of forensic entomology interest are presented and discussed.

DNA barcoding for identifying synanthropic flesh flies (Diptera, Sarcophagidae) of Colombia

The first step for a successful use of any insect as indicator in forensic sciences is providing a precise taxonomic identification at species level. Due to morphology-based identification of Sarcophaginae flies (Diptera, Sarcophagidae) is often difficult and requires strong taxonomic expertise, their use as forensic indicators has been limited. Consequently, molecular-based approaches have been accepted as alternative means of identification. Thus, we aimed testing the efficiency of the barcode region of the mitochondrial cytochrome oxidase subunit I (COI) gene for identification of synanthropic flesh flies of several species of the genera Peckia, Oxysarcodexia, Ravinia, and Tricharaea collected in Colombia. The 645-bp fragment of COI was amplified and aligned (215 parsimoniously informative variable sites). We calculated Kimura two-parameter genetic distances and reconstruct a Neighbor-Joining phylogenetic tree. Our Neighbor-Joining tree recovered all species as monophyletic, and confirmed a new species of the genus Ravinia as also indicated by the interspecific genetic divergences and morphological observations. We obtained a 100% of identification success. Thus, the COI barcodes showed efficiency as an alternative mean of identification of species of flesh flies collected on decaying organic matter in Colombia.

Can Sarcophagidae (Diptera) be the most important entomological evidence at a death scene? Microcerella halli as a forensic indicator

Although a corpse can harbor several species of flies, only a few have been sufficiently studied to be used as forensic indicators. Sarcophagidae are an example of how the forensic use of insects can be impaired by taxonomic and biological data limitation. This manuscript provides the first record of the Neotropical flesh fly Microcerella halli (Engel, 1931) on a human body and its use in forensics. M. halli and Sarconesia chlorogaster (Widemann, 1830) were sampled from a body located indoors at 20°C. Only M. halli was used to estimate the mPMI (minimum post mortem interval) because it was the oldest larval stage on the corpse. Based on the development time of M. halli we estimate an mPMI of at least 10 days. In addition, we provide for the first time a case in which a flesh fly was the main source of entomological evidence in Southern Brazil. We also provide evidence that Sarcophagidae arrived before Calliphoridae in this case, an unusual successional pattern.

A novel nuclear forensic tool involving deposit type normalized rare earth element signatures

AbstractIdentifying the provenance of uranium‐rich materials is a critical objective of nuclear forensic analysis. Rare earth element (REE) distributions within uranium ores are well‐established forensic indicators, but quantifying and correlating trace element signatures for U ores to known deposits has thus far involved intricate statistical analyses. This study reports average chondrite normalized (CN)‐REE signatures for important U deposit types worldwide, which are then employed to evaluate U ore paragenesis using a simple linear regression analysis. This technique provides a straightforward method that can aid in determining the deposit type of U ores based on their REE abundances, and combined with other forensic indicators (e.g. radiogenic isotope signatures) can provide essential provenance information for nuclear materials.

Age estimation during the blow fly intra-puparial period: a qualitative and quantitative approach using micro-computed tomography

Minimum post-mortem interval (minPMI) estimates often rely on the use of developmental data from blow flies (Diptera: Calliphoridae), which are generally the first colonisers of cadavers and, therefore, exemplar forensic indicators. Developmental data of the intra-puparial period are of particular importance, as it can account for more than half of the developmental duration of the blow fly life cycle. During this period, the insect undergoes metamorphosis inside the opaque, barrel-shaped puparium, formed by the hardening and darkening of the third instar larval cuticle, which shows virtually no external changes until adult emergence. Regrettably, estimates based on the intra-puparial period are severely limited due to the lack of reliable, non-destructive ageing methods and are frequently based solely on qualitative developmental markers. In this study, we use non-destructive micro-computed tomography (micro-CT) for (i) performing qualitative and quantitative analyses of the morphological changes taking place during the intra-puparial period of two forensically relevant blow fly species, Calliphora vicina and Lucilia sericata, and (ii) developing a novel and reliable method for estimating insect age in forensic practice. We show that micro-CT provides age-diagnostic qualitative characters for most 10% time intervals of the total intra-puparial period, which can be used over a range of temperatures and with a resolution comparable to more invasive and time-consuming traditional imaging techniques. Moreover, micro-CT can be used to yield a quantitative measure of the development of selected organ systems to be used in combination with qualitative markers. Our results confirm micro-CT as an emerging, powerful tool in medico-legal investigations.

An Informed Forensics Approach to Detecting Vote Irregularities

Electoral forensics involves examining election results for anomalies to efficiently identify patterns indicative of electoral irregularities. However, there is disagreement about which, if any, forensics tool is most effective at identifying fraud, and there is no method for integrating multiple tools. Moreover, forensic efforts have failed to systematically take advantage of country-specific details that might aid in diagnosing fraud. We deploy a Bayesian additive regression trees (BART) model–a machine-learning technique–on a large cross-national data set to explore the dense network of potential relationships between various forensic indicators of anomalies and electoral fraud risk factors, on the one hand, and the likelihood of fraud, on the other. This approach allows us to arbitrate between the relative importance of different forensic and contextual features for identifying electoral fraud and results in a diagnostic tool that can be relatively easily implemented in cross-national research.

Key to Adults of Afrotropical Species of the GenusChrysomyaRobineau-Desvoidy (Diptera: Calliphoridae)

Species of Chrysomya Robineau-Desvoidy are important in disease transmission and can be used as forensic indicators. An identification key is presented here for adults of the genus Chrysomya from the Afrotropical Region. Notes on the distribution and biology of the 12 species are also given.

Can soil testate amoebae be used for estimating the time since death? A field experiment in a deciduous forest

Estimation of the post-mortem interval (PMI, the time interval between death and recovery of a body) can be crucial in solving criminal cases. Today minimum PMI calculations rely mainly on medical and entomological evidence. However, beyond 4–6 weeks even entomological methods become less accurate. Thus additional tools are needed. Cadaveric fluids released by decomposing cadavers modify the soil environment and thus impact soil organisms, which may thus be used to estimate the PMI. Although the response of bacteria or fungi to the presence of a corpse has been studied, to the best of our knowledge nothing is known about other soil organisms. Testate amoebae, a group of shelled protozoa, are sensitive bioindicators of soil physico-chemical and micro-climatic conditions and are therefore good potential PMI indicators. We investigated the response of testate amoebae to three decomposing pig cadavers, and compared the pattern to two controls each, bare soils and fake cadavers, in a beach-oak forest near Neuchâtel, Switzerland. Forest litter samples collected in the three treatments over 10 months were analysed by microscopy. The pig treatment significantly impacted the testate amoeba community: after 22 and 33 days no living amoeba remained underneath the pig cadavers. Communities subsequently recovered but 10 months after the beginning of the experiment recovery was not complete. The fake cadavers also influenced the testate amoeba communities by altering the soil microclimate during a dry hot period, but less than the cadavers. These results confirm the sensitivity of soil testate amoebae to micro-climatic conditions and show that they respond fast to the presence of cadavers – and that this effect although decreasing over time lasts for months, possibly several years. This study therefore confirms that soil protozoa could potentially be useful as forensic indicators, especially in cases with a longer PMI.

Evaluation of bait attractiveness for forensically important flies in lowland and montane forest in Peninsular Malaysia

Background: Blowflies (order: Diptera, family: Calliphoridae) and house flies (order: Diptera, family: Muscidae) are important indicators to determine postmortem intervals in forensic entomology. Knowledge of the ecology and bionomics of individual species is necessary for the use of these flies as forensic indicators. Baited trapping is often employed to collect flies for such studies. However, the effect of baits on the diversity and abundance of baited trap collections is not known. Objective: To compare the sampling effectiveness of several types of bait in terms of diversity and abundance of forensically important flies. Materials and methods: The effectiveness of belacan (fermented shrimp paste), sugar, beef, ox liver, and fish were tested in three locations at different altitudes in Malaysia; Gombak Field Study Station (about 200 m above sea level (a.s.l.); N3°19′28″, E101°45′09″), Awana (about 1100 m a.s.l.; N3°24′03″ E101°46′59″) and Bukit Cincin (about 1700 m a.s.l.; N3°25′58″ E101°47′05″). Results: Fish consistently attracted more flies and species than other baits. Beef and ox liver produced moderate or inconsistent results. Flies were rarely attracted to preserved baits such as shrimp paste or odorless baits such as sugar. At higher elevations, flies were attracted to a wider variety of baits. Meat may cause a bias towards mated gravid females and produce a biased sample of the true population. Conclusion: Fish produced the most consistent results in terms of highest number of flies collected and wide diversity of species sampled, odor, especially from rotting meat, is important in attracting carrion flies.

Coleopterofauna found on fresh and frozen rabbit carcasses in Curitiba, Paraná, Brazil

Many arthropod species are associated with carrion and some of them can be used as forensic indicators in murder investigations to estimate the time of death. Different physical conditions of cadavers may influence the fauna and the importance of freezing and thawing is unknown. The present paper sought to survey the Coleoptera species encountered in frozen and fresh rabbit carcasses, at a forest in Curitiba, Brazil. Four rabbit carcasses, two of them fresh and the other frozen were used. The coleopterofauna was sampled daily, and analyzed using non-parametric tests. A total of 666 beetles were sampled, belonging to 28 species in 10 families. Most of the beetles captured were larvae of Oxelytrum spp. (433) which are known to be necrophagous. The two frozen carcasses accounted for most of the beetles (338 and 180) in comparison with the two fresh carcasses (103 and 45). The tests were based on the most abundant species. Oxelytrum spp. median differed significantly between carcasses (H = 12.47844; p = 0.0059). The two fresh carcasses differed significantly (U = 190.0; p = 0.00019), but there was no significant difference between the frozen carcasses (U = 336.0; p = 0.29755). The data indicate that the freezing process prevents certain species to colonize carcasses, in this case with the dominance of species of Oxelytrum. These data also indicate that careful attention is necessary before using frozen carcasses in forensic entomology studies.

Can fatty acid and mineral compositions of sturgeon eggs distinguish between farm-raised versus wild white (Acipenser transmontanus) sturgeon origins in California? Preliminary report

The objective was to investigate the potential of using fatty acid and mineral compositions of sturgeon eggs to distinguish their source, either farm-raised or wild fish. Trafficking of illegally obtained wild white sturgeon eggs is a major concern to the California Department of Fish and Game, but there is no forensic method to separate wild and farm-raised white sturgeon eggs. The extension of these findings in future work will be to use the fatty acid and mineral compositions as forensic indicators of caviar produced legally from farm raised sturgeon compared with illegal caviar produced from sturgeon poached from the wild. Samples (10) of sturgeon eggs were collected from a commercial aquaculture facility in the Sacramento Valley. Eggs from wild sturgeon (9) were obtained primarily from confiscations of illegally caught sturgeon by fish and game law enforcement personnel. The total lipid content of sturgeon eggs was analyzed for fatty acid composition. The most notable difference was the higher concentration (P<0.001) of C18:2n6 in farm raised eggs (6.5mg/100g total lipid) than wild eggs (0.6mg/100g total lipid) while other differences between fatty acids were smaller. Eicosapentaenoic acid (C20:5n3) was higher (P<0.02) in farm-raised (5.56mg/100g) than wild (4.49mg/100g). Docosahexaenoic acid (C22:6n3), C18:1 cis 9&10, and C20:4n6 were not different for origin of the eggs. Concentration of selenium was markedly higher (P<0.001) in eggs from wild sturgeon (10.0mg/kg dry weight) than farm-raised sturgeon (2.7mg/kg dry weight). Concentrations of iron, zinc, copper, phosphorus, sulfur, calcium, and potassium did not differ between farm-raised and wild eggs. Arsenic concentration in wild eggs was 3.3mg/kg dry weight whereas arsenic was not detected in the farm-raised eggs. Fatty acid and mineral compositions of eggs differed significantly between farm-raised and wild sturgeon and these should be investigated further as biological markers for forensic identification of caviar origin.

Insects Breeding in Pig Carrion in Two Environments of a Rural Area of the State of Minas Gerais, Brazil

The main objective of this study was to identify potential forensic indicators in the insect fauna associated with pig carrion and the pattern of insect succession during the decomposition process in two environments of a rural area in Uberlândia, State of Minas Gerais, Brazil. The study was conducted at two locations: in a pasture and in a fragment of a semi-deciduous forest (vegetation profile of the Cerrado biome) in two different seasons (rainy and dry) of 2010. The decomposition process was more rapid in the rainy season. More than 32,000 insects belonging to 17 species of 6 families of Diptera and 2 species of Coleoptera bred in the carcasses. The majority of Diptera bred in the first three stages of decomposition. However, Phoridae and Coleoptera bred mainly in the last two stages. The insects bred more abundantly in the pasture and in the humid season. The exceptions were the Fanniidae (Diptera), which bred more abundantly in the forest and the Dermestidae and Cleridae (Coleoptera), which did not demonstrate any preference in terms of environments and were more abundant in the dry season, respectively. Species such as Chrysomya albiceps (Wiedemann), Peckia (Patonella) intermutans (Walker), Necrobia rufipes (De Geer), and Dermestes maculatus (De Geer) may be potential indicators of post-mortem interval. Hemilucilia segmentaria (Fabricius) and Ophyra aenescens (Wiedemann) may be indicators of localization of the natural environment, while Musca domestica Linnaeus may be an indicator of the anthropic environment. The study thus presented many species of potential forensic indicators in rural areas of this region.

INSETOS DE POTENCIAL IMPORTÂNCIA FORENSE E NA SAÚDE PÚBLICA EM REGIÃO URBANA DE MINAS GERAIS: FREQUÊNCIA RELATIVA E VARIAÇÃO SAZONAL DE FAUNA ATRAÍDA E CRIADA EM CARCAÇAS DE ROEDORES

Necrophagous insects may be important forensic indicators. Many necrophagous flies are also capable of transmitting pathogens and causing facultative myiasis in humans. The present study aimed at obtaining information on the necrophagous insects of the urban area of Uberlândia, State of Minas Gerais, Brazil. Carcasses of rodents were exposed in three different locations in the city until their complete decomposition, during autumn, winter, and spring of 2007 and summer of 2008. Thetraps used consisted of a cage where the carcasses were placed under a pyramid-shaped cover. Trays containing sawdust were placed under each cage for retention of immature and ambulatory adult insects. A total of 1,797 insects were collected in the traps and an other 5,937 specimens were bred in the carcasses. The attracted insects belonged to at least 51 species of 15 families of dipterans and coleopterans. Representatives of Hymenoptera, Hemiptera and Lepidoptera were also colleted. TheSarcophagidae were the most diverse family and Tricharaea (Sarcophagula) occidea (Fabricius, 1794) (Diptera: Sarcophagidae) was the most abundant species. The insects bred in the carcasses belonged to 18 species of Diptera and one Coleoptera. The blowfly, Lucilia eximia (Wiedemann, 1819) (Diptera: Calliphoridae) was the most abundant, corresponding to 75% of the bred specimens. Several species bred exclusively or almost exclusively in only one season of the year. Peckia species (Sarcophagidae) bred only in winter, Hemilucilia segmentaria (Fabricius, 1805) (Diptera: Calliphoridae) only in the fall and Musca domestica Linnaeus (Diptera: Muscidae) and Dermestes maculatus (DeGeer, 1774) (Coleoptera: Dermestidae) bred only in the spring. The results appoint to several potential species as forensic indicators in the urban area of Uberlândia, MG.

Carrion flies of forensic interest: a study of seasonal community composition and succession in Lisbon, Portugal

Information on Diptera community, seasonality and successional patterns in every geographical region is fundamental for the use of flies as forensic indicators of time of death. In order to obtain these data from the Lisbon area (Portugal), experiments were conducted during the four seasons of the year, using piglet carcasses as animal models. Five stages were recognized during the decomposition process. The stages, besides visually defined, could be separated taking into account the occurrence and abundance of the specific groups of Diptera collected. In general, the bloated stage recorded higher abundance and species-richness values. Seventy-one species were identified, belonging to 39 families, in a total of 20 144 adult Diptera collected. Autumn yielded the highest values of species richness, whereas winter had the lowest. In all seasons of the year, Calliphoridae was the dominant family; Muscidae and Fanniidae were very abundant as well. Calliphora vicina Robineau-Desvoidy, Calliphora vomitoria (Linnaeus), Chrysomya albiceps (Wiedemann), Lucilia ampullacea Villeneuve, Lucilia caesar (Linnaeus), Lucilia sericata (Meigen) (Calliphoridae), Hydrotaea ignava (Harris), Muscina prolapsa (Harris), Synthesiomyia nudiseta (van der Wulp) (Muscidae), Piophila megastigmata McAlpine, Stearibia nigriceps (Meigen) (Piophilidae) and Nemopoda nitidula (Fallén) (Sepsidae) were revealed to be very important members of the Diptera community collected. The necrophagous behaviour, demonstrated by their immatures, using carrion as a food source makes them useful forensic indicator species. Also of relevance is the presence of Chrysomya megacephala (Fabricius), S. nudiseta and P. megastigmata, foreign species established in the local carrion communities. This study also marks the first record of S. nudiseta in Portugal.

Occurrences of flesh flies (Diptera: Sarcophagidae) on human cadavers in Switzerland, and their importance as forensic indicators

From 1993 to 2008, criminal investigations were conducted in the western part of Switzerland with special attention to blowfly and flesh fly species in order to estimate the post-mortem interval when requested by the police authorities. Flesh flies were found in only 33 cases out of 160. Five species of the genus Sarcophaga were identified (S. africa, S. argyrostoma, S. caerulescens, S. similis and S. sp.). The main species found on corpses (larval stage) was S. argyrostoma. The thermal constant (K) calculated for this species in Switzerland is 380.6 ± 16.3 (mean ± S.D.) degree-days. With the exception of S. caerulescens, found three times in the larval stage on corpses, the three other species are of minor forensic importance. S. argyrostoma is found during summer and indoors. This species colonises dead bodies, usually the same day as blowfly species, and it could be used to estimate the post-mortem interval. Other species are discussed in the light of current knowledge on their biology and ecology. It is recommended that voucher material be deposited in a museum, allowing further studies by relevant specialists, thereby helping investigators and avoiding misidentifications.

Elections and Democracy: To Cheat or to Change?

The Forensics of Election Fraud: Russia and Ukraine. By Mikhail Myagkov, Peter C. Ordeshook, Dimitri Shakin. Cambridge: Cambridge University Press, 2009. 289 pp., $30.99 paperback (IBSN-13: 978-0-521-74836-0). The Politics of Electoral Reform: Changing the Rules of Democracy. By Alan Renwick. Cambridge: Cambridge University Press, 2010. 312 pp., $90.00 hardcover (IBSN-13: 978-0-521-76530-05). Cambridge University Press has released two monographs recently that deal with the complex relationship of elections and democracy. Though substantively distinct, these books both address a core concern regarding the ways political actors attempt to influence electoral outcomes and the consequences of such attempts for democracy. For Myagkov, Ordeshook, and Shakin, the question is: how can we detect election fraud where we suspect it has occurred? Renwick's questions center on the dynamics of electoral system reform. Both works bring an arguably under-utilized methodological approach to bear on their questions, and both provide empirical analysis of a small number of cases. As indicated by the title, The Forensics of Election Fraud , Myagkov et al. investigate election fraud in Russia and Ukraine, while Renwick's The Politics of Electoral Reform traces the process of electoral system reform in France, Japan, Italy, and New Zealand. Myagkov et al. attribute their motivation for Forensics to the work of one Dr. Alexander Sobyanin, a scholar committed to exposing electoral fraud in Russia. In many ways, the book maintains this tight focus throughout, though one can certainly imagine theoretical extensions and methodological applications. The authors’ fraud detection efforts focus very specifically on those illegal activities that directly distort election results: ballot box stuffing and the deliberate manipulation of vote counts. They introduce three forensic indicators of election fraud, based on the logic of what fraud-free elections should look like, in terms of turnout, candidate vote shares, and the relationship between the two. Deviations from any of these three expectations might indicate fraud. First, they argue that as turnout increases so should the votes for each candidate, at a rate proportional to their support in the electorate. Second, they argue that turnout should be normally distributed across districts, with small proportions of high and low turnout districts …

Molecular phylogeny of the blowfly genus Chrysomya

Chrysomya Robineau-Desvoidy (Diptera: Calliphoridae) is a genus of blowfly commonly observed in tropical and subtropical countries of the Old World. Species in this genus are vectors of bacteria, protozoans and helminths, cause myiasis, are predators of other carrion insects, and are important forensic indicators. Hypotheses concerning the evolution of sex determination, larval anatomy and genome size in Chrysomya have been difficult to evaluate because a robust phylogeny of the genus was lacking. Similarly, the monophyly of subgenera was uncertain. The phylogeny of Chrysomya spp. was reconstructed based on 2386 bp of combined mitochondrial cytochrome oxidase subunit I (COI) and nuclear carbamoylphosphate synthetase (CPS) genes. Maximum parsimony (MP), maximum likelihood (ML) and Bayesian analysis (BA) differed only slightly in the resulting tree topology. Chrysomya was monophyletic. Monogenic reproduction is almost certainly derived rather than, as has been suggested, primitive within the genus, and tuberculate larvae probably evolved twice. Genome size is more likely to have decreased over evolutionary time rather than, as has been suggested, increased within the genus, but its correlation with developmental time was not observed. The subgenera Microcalliphora, Eucompsomyia and Achoetandrus were recovered as monophyletic.

A new dipteran forensic indicator in buried bodies

The first breeding records of miltogrammine fleshflies in buried vertebrate carrion are presented. First instars of Eumacronychia persolla Reinhard (Nearctic) (Diptera: Sarcophagidae) and Phylloteles pictipennis Loew (Palaearctic) (Diptera: Sarcophagidae) are able to penetrate dry, loose soil and reach deeply buried animal remains, an ability which distinguishes is unique to necrophagous Calyptratae. Their broad geographical distribution, fast location and colonization of carrion, complete development on buried food resources and easy identification make these species useful forensic indicators in buried bodies in dry habitats.

Decomposition and dipteran succession in pig carrion in central Argentina: ecological aspects and their importance in forensic science

Data on the insect species associated with corpse decomposition are particularly important for estimation of the post-mortem interval (PMI) in forensic science because the PMI is based on the lifecycle and behaviour of necrophagous insects, among other measures. To determine the dipteran succession on pig carrion, four experiments, one in each season, were carried out during 2004 in a rural area of Córdoba, central Argentina. Two pigs (Sus scrofa L.) were used in each of the four experiments. At each time-point one pig was placed in the shade and the other under direct sunlight. Insects were collected daily during the first 4 weeks and thereafter every 2 or 3 days. Five stages of decomposition were observed and a total of 24 710 adult specimens were collected, belonging to the following eight families of Diptera: Calliphoridae; Muscidae; Sarcophagidae; Phoridae; Piophilidae; Fanniidae; Sphaeroceridae, and Anthomyiidae. All Calliphoridae collected in this study were considered to be of potential forensic importance because of their necrophagous behaviour and because their immature stages use carrion as a food source. Other species, such as Musca domestica L. and Ophyra aenescens (Wiedemann), were also considered to represent potential forensic indicators.