Use of necrophagous insects as evidence of cadaver relocation: myth or reality?

Context

This article reviews the current knowledge and potential of different methods involving the use of insects to study cadaver relocation and evaluates their feasibilities.

Insect analysis has been used in legal investigations for decades in a practice now known as forensic entomology (Benecke, 2001). Increased interest in this field since the late 20th century has resulted in more frequent use of forensic entomology in investigations and the development of research on necrophagous species. Previous reviews have compiled and explained the aims and methods of forensic entomology (Catts & Goff, 1992; Byrd & Castner, 2009, Bala, 2015), but some fundamental questions remain unresolved, particularly the potential use of insects as evidence of corpse relocation.

Cadaver decomposition can be altered due to human activity, especially steps taken to hide a cadaver (Haglund & Sorg, 1997; Mann, Bass & Meadows, 1990). Attempts to prevent discovery include cadaver concealment, wrapping, and displacement. Such post-mortem relocation can occur shortly after death or after days of concealment. It can occur over short (e.g., from the room where death occurred to the garden of the house) or long distances. In most cases, the location where the cadaver is hidden is very different from that where death occurred (Reibe et al., 2008). Currently, only a few scientific methods are available to determine whether a crime scene is a primary or secondary scene (Miller Coyle et al., 2005). Because the biology and ecology of necrophagous species can convey information on where and how insects live, forensic manuals and courses often state that insects can be used as evidence of cadaver relocation (Catts & Goff, 1992; Byrd & Castner, 2009; Smith, 1986; Joseph et al., 2011; Mozayani & Noziglia, 2011; Archer & Wallman, 2016; Payne-James & Byard, 2015). However, while this idea is appealing, it may not reflect reality.

It may seem obvious that “if a body is discovered with insects restricted to a habitat or geographic region different from that in which it is discovered, this is an indication that the body may have been moved following death” (Mozayani & Noziglia, 2011). However, most, if not all, European necrophagous species have large distribution areas covering many countries and hundreds of thousands of square kilometers, making the sampling of non-native species within European regions unlikely. Furthermore, while each species has an ecological niche (e.g., forest or synanthropic environment; sunny or shady habitats), individuals can sometimes occur outside the preferred range. Additionally, the long dispersal capability of most necrophagous species, notably blow flies, makes it difficult to relate a given species to a particular place or habitat and thus draw inferences regarding cadaver relocation (Nazni et al., 2005; Bomphrey, Walker & Taylor, 2009, Zabala, Díaz & Saloña-Bordas, 2014).

Temporal separation is another characteristic of necrophagous species. The phenology (cyclic and seasonal phenomena) of blow flies is well known; some species are primarily active during hot weather, whereas others are adapted to cold climates (Voss, Spafford & Dadour, 2009). Under some circumstances, such seasonality might contribute useful information regarding the chronology of cadaver decomposition. However, the presence of larvae of a summer species on a cadaver discovered in the winter does not constitute indisputable evidence of cadaver relocation. In addition, colonization time is strongly dependent on the stage of decomposition. Although it is far more complex than squads (Wyss, Cherix & Mangin, 2013), succession on cadavers has been experimentally shown in several countries and under a variety of conditions (Anderson & Van Laerhoven, 1996; Abd El-Bar & Sawaby, 2011; Abouzied, 2014; Archer, 2014). Divergence from known succession patterns, such as the absence of certain species or unusual associations, might indicate cadaver relocation or concealment. The presence or absence of some instars is also of relevance, especially with regard to wandering larvae or pupae of pioneer species (e.g., Calliphoridae flies), which pupate away from the cadaver and can thus be found after cadaver removal.

Advances in genetics also offer numerous opportunities. Genetic analyses allow the assignment of individuals to local populations or even sub-populations. As noted by Tomberlin et al. (2011), such analyses are of great interest in the context of cadaver relocation. In addition, the genetic analysis of gut contents has potential for identifying the cadaver that larvae have been feeding on (Campobasso et al. (2005) and Calvignac-Spencer et al. (2013)). This technique should be developed in the coming years and provide new tools for forensic entomologists and crime scene investigations.

This review analyzes in detail these different approaches. It reveals weaknesses and mistaken beliefs regarding the use of forensic entomology as evidence of cadaver displacement as well as many promising aspects and development opportunities.

Survey methodology

The first phase of the survey involved identifying the magnitude of the issue of cadaver relocation. This phase was performed by searching the main forensic literature published in English over the last 40 years for studies addressing corpse relocation. We found references to this idea in several forensic entomology books and studies (Catts & Goff, 1992; Byrd & Castner, 2009; Smith, 1986; Joseph et al., 2011; Mozayani & Noziglia, 2011; Archer & Wallman, 2016; Payne-James & Byard, 2015), but few case reports (Goff, 1991; Benecke, 1998; Krikken & Huijbregts, 2001). We also found several research articles addressing corpse relocation as a main goal or claiming the potential application of their findings to this topic. From this dataset, we outlined various facets of the problem and gathered them into four main concepts: spatial separation, behavior/development, phenology/colonization time, and molecular analyses. Then, we searched the literature within each of these fields for data on the potential use of different methods to study corpse relocation. The resulting dataset was then analyzed to identify discrepancies or methods with strong application potential.

Due to the number of factors that can affect insect occurrence on corpses (e.g., species, climates, and geography), we focus on the central European area. However, most of the conclusions of this review can be generalized to other locations.

Biogeography of European species of forensic importance

According to the common definition, the distribution of a species is the geographical area within which that species is observed. Species may not be uniformly distributed in this area: variation in local density (e.g., a clumped distribution) is common. However, individuals of a given species are not often observed outside of their distribution area. Online interactive maps can now be found on the web for most European taxa. Many of these databases combine older distribution data and contemporary records from amateur or professional entomologists (Global Biodiversity Information Facility, 2017). Such collaborative work is subject to information gaps and biases, particularly a lack of records; as a result, species distribution maps sometimes reflect the distribution of specialists more than the distribution of species (Fig. 1). In particular, a lack of records affects necrophagous species, which are infrequently sought out and are poorly known among entomologists. As a result, a necrophagous species detected in previously unsampled site may be considered unusual/unexpected while in fact being well within the species’ distribution.

To be informative in determining cadaver relocation, a necrophagous species must have a restricted and well-established distribution. Herein, we list here the few European necrophagous species meeting these criteria.

Two common species of the genus Cynomya have restricted distributions within Europe. Cynomya mortuorum, a large, hairy bluebottle fly, can be found across the entire Palearctic region (Braet et al., 2015) (Fig. 1). But this species is rarely reported in central European countries, especially in a forensic context (Rognes, 1991; Starkeby, 2001; Dekeirsschieter et al., 2013; Wyss, Cherix & Mangin, 2013; Braet et al., 2015). Its distribution partially overlaps that of Cynomya cadaverina (Robineau-Desvoidy, 1830), another cold-adapted species of forensic interest (Rognes, 1991; Kurahashi & Kuranishi, 2000).

Two other calliphorid flies, Calliphora loewi and Calliphora subalpina, show a sub-alpine distribution (Faucherre, Cherix & Wyss, 1999; Rognes, 1991). In Europe, Calliphora loewi is mostly found in northern and central Europe, from Siberia and the Caucasus to the Central European Territories (Smith, 1986). Although this northern distribution area suggests that this species might be a good indicator of relocation, its recent discovery in Madeira Island (Portugal) calls its relevance into question (Prado e Castro et al., 2016). Furthermore, although it has a large distribution, Calliphora loewi is often recorded at low abundance, making sampling of this species on a relocated corpse unlikely (Szpila et al., 2014). Calliphora subalpina has a very similar distribution area and is subject to similar limitations (Rognes, 1991).

Chrysomya albiceps is one of the few species that is theoretically usable as an indicator of cadaver relocation in Europe (Grassberger, Friedrich & Reiter, 2003). The species is meridional, common and abundant in southern Europe and in most of the Neotropical, Afrotropical, and Oriental regions (Grassberger, Friedrich & Reiter, 2003). However, while it is mostly found in southern Europe, Chrysomya albiceps has been observed migrating northward during the hot summer months (Wyss, Cherix & Mangin, 2013). This northward expansion of its range has the potential to cause confusion and precludes its use as evidence of cadaver relocation. Similar factors affect the use of Chrysomya megacephala, an Asian fly recently recorded in continental Europe and extending its distribution into the Mediterranean region (Martinez-Sanchez, Marcos-Garcia & Rojo, 2001; Ebejer, 2007; Prado e Castro & García, 2010; Bao & Wells, 2014).

Some additional necrophagous species also have restricted distribution areas, but most of these species are unusual, difficult to identify and poorly documented. Thus, although they may be informative, these insects cannot be regarded as true indicators of cadaver relocation according to the criteria listed by Matuszewski, Szafałowicz & Jarmusz (2013). According to this review, to date, insect distribution area as an indicator of long-distance cadaver relocation appears to be limited in application, with little utility for empirical forensics. However, the distribution of Cynomya mortuorum (Fig. 1) is a great example of an incomplete dataset that could be easily enhanced by forensic case databases and natural history collections targeted on carrion feeding insects. This example also highlights the potential of species distribution models based on environmental niche modeling, e.g., maximum entropy algorithm (MaxEnt) (Szyniszewska & Tatem, 2014; Ali Hanafi-Bojd et al., 2015; Kumar, Yee & Neven, 2016). Such models can provide probabilities of the locations of certain insects in a given area and could be used in a forensic context to determine the likelihood of cadaver relocation.

Species-specific habitats

Many forensic cases involve cadavers that have been transported some kilometers from the crime scene, especially to low-traffic areas such as forests, dumping sites, rivers, or seashores (secondary decomposition sites) (Matuszewski, Szafałowicz & Jarmusz, 2013). As discussed above, such short-distance relocation cannot be elucidated using the presence of foreign necrophagous species. However, the transfer of a cadaver to a new location can alter micro-environmental conditions such as climate, extent of synanthropy, vegetation conditions, and indoor/outdoor location. The population of necrophagous insects at the secondary decomposition site may therefore differ from that of the initial (primary) environment.

The effect of habitat on the abundance of certain species is well established (Hwang & Turner, 2005; Brundage, Bros & Honda, 2011). However, published data regarding species-specific habitats vary, highlighting that such preferences are not fixed and often vary locally. The biology of necrophagous species contributes to this variability. To successfully reproduce, adult females must find suitable carrion for their offspring. However, the occurrence of cadavers is by definition unpredictable because death is temporally and spatially random. Accordingly, all necrophagous species have an efficient olfactory sense that allows individuals to quickly detect and locate cadavers. As noted by MacLeod & Donnelly (1957b), blow flies are powerful and active flies capable of dispersing over large distances (several kilometers per day).

Furthermore, most studies in forensic entomology use simple descriptors (e.g., forest, sunny, and indoor) without taking into account the surroundings or variability within categories (e.g., forest type or city size). Additionally, larger-scale effects and interactions of parameters (e.g., temperature and city size) are typically not considered (Zabala, Díaz & Saloña-Bordas, 2014). In a 1957 study, MacLeod and Donnelly stated that “there is nothing to indicate whether the non-uniform distribution of the adult (flies) population is due to the faunal, floral, vegetation-structural or edaphic element of the environment, or to some combination of these.” More than fifty years later, Zabala, Díaz & Saloña-Bordas (2014) concluded that, except for the summer abundance of Calliphora vomitoria, blow fly community composition could not be used as evidence of cadaver relocation, particularly in heterogeneous and densely populated areas. These authors also noted that conclusions based on species-specific habitat preferences should be drawn only on the basis of local studies (Davies, 1990; Anderson & Van Laerhoven, 1996; Hwang & Turner, 2005; Brundage, Bros & Honda, 2011). The following sub-section focuses on specific habitat characteristics that may be of relevance in determining the primary deposition site of a cadaver.

Conclusions related to species-specific habitats

As described herein in detail, the associations of species to specific habitats can be used to infer cadaver relocation from one habitat to another (Table 1). However, whereas entomological evidence related to species-specific habitats may help support or reject hypotheses regarding cadaver relocation, inferences unsupported by local data are typically not appropriate. Currently, most published information is based on restricted datasets; future work should focus on obtaining large amounts of data at the local scale. For example, a posteriori analysis of forensic entomology case databases could provide substantial information on the biology of necrophagous species (e.g., species found on indoor vs. outdoor corpses, seasonal prevalence of specific species) (Dekeirsschieter et al., 2013; Disney et al., 2014; Charabidze et al., 2014, 2016; Syamsa et al., 2017). Back-testing field experiments should always be performed to verify the local applicability of interpretations.

Non-necrophagous species can also provide evidence of cadaver relocation. As reported by Goff (2011): “If a body is outdoors near or under vegetation, it is possible for insects associated with that vegetation to move onto the body, although typically not to feed or lay eggs.” However, as these insects are not directly associated with the cadaver, it may be difficult to conclude that they were moved together with it. Furthermore, the probability of having a non-necrophagous species (1) moving onto a cadaver, (2) being moved with the cadaver, (3) being sampled and identified at the secondary site, and (4) being located outside its natural range is likely very low. We have found no report of such a case in the forensic literature.

Adult behavior: colonization and egg laying

Egg laying on a cadaver is affected by climatic conditions, species behavior and cadaver accessibility: in theory, these parameters could be used to infer displacement between places with different climactic conditions. Krikken & Huijbregts (2001) reported a neat but questionable example of this concept. Based on the unverified assumption that Lucilia sericata females “oviposit on high temperature surfaces,” the authors concluded that a cadaver discovered in a room had first been located outdoors in a warm and sunny place. However, although L. sericata is heliophilic, it can lay eggs indoors.

Though a species-specific minimum temperature is required for egg laying (Hédouin et al., 1996; Faucherre, Cherix & Wyss, 1999; Ody, Bulling & Barnes, 2017), several other weather parameters, such as the levels of sun, wind and rain, can also have effects on egg laying. Fly displacement and egg laying primarily occur during the daytime (Wooldridge, Scrase & Wall, 2007; Greenberg, 1990b; Benecke, 1998; Wells et al., 2001). Accordingly, the presence of numerous egg batches on a cadaver located in a dark place suggest the possibility of cadaver relocation. However, Faucherre, Cherix & Wyss (1999) reported a case where Calliphora vicina females had flown to and oviposited on a cadaver in a 10-m-deep cave located in the Swiss Jura mountains, and Gemmellaro (2016) recently showed the ability of some calliphorid flies, especially Calliphora vicina, to reach meat-baited traps placed inside volcanic caves.

Some species are known to oviposit in specific areas of a cadaver. For example, calliphorid flies preferentially deposit egg batches on the face (nostrils, mouth, and eyes), whereas most silphid beetles lay their eggs underneath the cadaver (Smith, 1986). However, the region of oviposition is strongly affected by the extent of cadaver decomposition or wounds, the presence of other larvae and species, collective behavior (egg aggregation) and environmental characteristics (Charabidze et al., 2015). On the other hand, strong evidence of cadaver relocation is provided by the presence of eggs, especially those of large calliphorids, in inaccessible places, such as underneath a cadaver. Such a case was analyzed in France (D. Charabidze, 2013, unpublished data): the presence of numerous Lucilia sericata and Calliphora vicina egg batches in the folds of clothing underneath a cadaver served as evidence of the secondary reversal of the cadaver by drug addicts searching for money.

Larval development, wandering larvae, and pupae

Fly larvae live on the cadaver and are thus very resistant to cadaver relocation. In contrast, the probability of transferring insects present in the soil or below the cadaver (wandering larvae, pupae, and most silphid larvae) along with the cadaver is very low. Accordingly, considerable information can be obtained from the presence and location of wandering larvae and pupae/puparia around a cadaver.

During the post-feeding stage, the larvae of several blow fly species (with the notable exception of Chrysomyinae species) begin to migrate from the cadaver to pupate in a protected location away from predators (Gomes, Godoy & Von Zuben, 2006). Greenberg (1990a) observed that more than 80% of post-feeding larvae of Lucilia sericata and Calliphora vicina removed of the cadaver to a distance up to 8 m away. In contrast, only 2% of Phormia regina, 10% of Muscina stabulans, and 16% of Chrysomya rufifacies larvae moved away from the cadaver. However, Lewis & Benbow (2011) reported cases of en masse post-feeding dispersal of Phormia regina larvae away from swine carcasses in experiments conducted during the summer. This unexpected observation illustrate the need for careful case-by-case analysis before drawing conclusions.

The presence of necrophagous blow fly pupae and puparia (or dead adult flies) in an empty place can be evidence of the former presence of a cadaver. This question was extensively discussed during the famous Casey Anthony trial (USA) (Lohr, 2011), in which a first forensic entomologist relied on the presence of numerous Megaselia scalaris larvae, pupae and adults in a car trunk as evidence of the former presence of a cadaver. However, an expert witness for the defense showed that the same insects could have come from a trash bag discovered in the trunk. As the gut contents of insect samples were not tested for DNA, there was no evidence to support the assertion that the insects originated on human remains (Campobasso et al., 2005, see the molecular analysis section of this review). Benecke (2004) described a similar case. The corpse of a man was discovered in the trunk of his car. Only a few larvae and pupae were sampled on the cadaver, but no pupae was found in the gaps of the trunk. The author postulates that the cadaver was stored in another place until post-feeding larvae left the corpse. Afterward, the corpse was moved into the car trunk, explaining why only a few maggots were found on the cadaver. Conversely, Krikken & Huijbregts (2001) reported a skeleton found during the winter in a small forest with “numerous empty pupal cocoons of Protophormia terraenovae under the bones.” Based on the presence of these puparia, the authors concluded that the entire decomposition process had taken place in that same place. However, as this species can pupate in clothes or on decomposing tissues, it is possible that the pupae had been moved together with the cadaver. Lastly, Mariani et al. (2014) observed that blow fly and muscid larvae buried with a cadaver ultimately left their food source to move to their typical pupariation depths. According to those authors, the presence of large numbers of post-feeding blow fly larvae without a cadaver in the vicinity could indicate that a body may have been buried nearby rather than relocated.

Cadaver relocation can sometimes be characterized by discrepancies between local temperature and larval development. For example, the presence of third-instar Lucilia sericata individuals on a cadaver located in a cold location (e.g., a cellar with a constant 9–10 °C temperature) would suggest relocation. However, such discrepancies often result from changes in microclimate (e.g., direct sun exposure vs. shade), larval-mass effect or conservation of the samples (e.g., high temperature during transport) rather than from relocation. Cadaver relocation should be considered as a possibility only in the absence of these other influences.

Lastly, the presence of crushed pupae/imago on or under the cadaver can be indicative of relocation. We observed the presence of flattened pupae or newly hatched flies (flat, dry individuals with a still-visible ptilinum) directly under the cadaver in several forensic cases. In these cases, relocation of the cadaver had likely occurred after numerous flies had started to emerge, and some specimens were compressed under the cadaver during or after moving. If such specimens are observed on site (before the cadaver is moved by the forensic team), relocation after larval pupation might have occurred.

Cuticular hydrocarbons

The ability to identify forensic species at different developmental stages and their associations with local populations can be crucial in determining whether a body was moved from a crime scene. Simple molecular analyses concern cuticular hydrocarbon profiles. Insects form a thin, epicuticular layer of wax consisting of free lipids, which is a class of compounds that includes hydrocarbons, alcohols, fatty acids, waxes, acylglycerides, phospholipids, and glycolipids (Gibbs & Elizabeth, 1998). The cuticular hydrocarbon phenotype is biologically very stable and almost entirely determined by genotype (Wells & Stevens, 2010; Pechal et al., 2014). Byrne et al. (1995) showed that the cuticular hydrocarbons of three geographically distinct populations of Phormia regina are differentiable. However, some local populations can interbreed with adjacent populations, and the minimal interval over which adjacent populations can be considered distinct remains unknown. Accordingly, this method could be used to identify the presence of a non-local population on a cadaver (which suggests cadaver relocation) but will not be informative in cases of short-distance relocation (Byrne et al., 1995). More research on this promising topic should be conducted in the future (Tomberlin et al., 2011).

Genetics of insect populations

DNA-based identification is valuable for identifying adult insects of forensic interest as well as immature stages, cuticle fragments, and puparia (Sperling, Anderson & Hickey, 1994; Zehner et al., 2004; Guo et al., 2010; Li et al., 2010; Wells & Sperling, 2001; Mazzanti et al., 2010; Xinghua et al. 2010; Guo et al., 2011; Zaidi et al., 2011; Jordaens et al., 2013; Meiklejohn, Wallman & Dowton, 2013; Park et al., 2013, Sonet et al., 2013). If post-mortem changes are suspected, relocation can be evidenced by determining the relationships between insects sampled at the initial and secondary sites (Picard, Villet & Wells, 2012). Several studies have highlighted significant genetic differences between populations of the same species within (Hall et al., 2001; Boehme et al., 2013; Desmyter & Gosselin, 2009; Sonet et al., 2013) and among continents (Hall et al., 2001; Lyra et al., 2005). To identify genetic variation among populations, methods such as simple conformation polymorphism strand analysis (SSCP) and amplified fragment length polymorphism (AFLP) are available. However, kinship analyses require a solid genetic database that encompasses variability among geographical sites, the development of which requires thorough field sampling, precise morphological identification and the complete genetic characterization of each collected individual.

Databases such as GenBank and the German Barcode of Life (2017) have been used to detect genetic variation within local populations of the same species (Wells & Stevens, 2010). Using SSCP analysis, inter-population differences have been detected between African and North American populations of the common housefly, Musca domestica (Marquez & Krafsur, 2003). Harvey et al. (2003) found differences in the COI gene between South African and Australian populations of two species of forensic interest, Chrysomya rufifacies and Lucilia cuprina. Furthermore, Desmyter & Gosselin (2009) and Boehme, Amendt & Zehner (2012) found sequence differences between Phormia regina specimens from North America and Europe. Jordaens et al. (2013) confirmed this divergence in the COI gene between P. regina populations with newly sequenced material. However, sequence divergence within each continent was only ca. 0.4%, making genetic differentiation of local strains difficult to detect. At the local scale, blow flies show genetic isolation by time but not distance. Scientific projects dedicated to building datasets that reflect the diversity of necrophagous entomofauna at the European scale are currently expanding and are expected to address this topic in the near future (Sonet et al., 2013; Geiger et al., 2016).

Using AFLP surveys, Picard and Wells observed that groups of adult Lucilia sericata and Phormia regina individuals trapped together on a bait were predominantly composed of related individuals, with a level of genetic diversity lower than that observed at a larger scale (Picard & Wells, 2009, 2010). This pattern is also observed in gravid females and is likely exhibited by larvae, suggesting that the population genetic structure of adults could be extended to the larval population growing on a cadaver. Such a finding would support the potential use of genetic tests to infer post-mortem relocation of a cadaver: for example, a larva found in one location might belong to a larval population growing on a cadaver in a second location. Faulds, Wells & Picard (2014) confirmed the validity of the AFLP method, finding that kinship testing based on AFLP data yielded adequate kinship estimates with limited error. As noted by those authors, this type of analysis can be performed on any life stage of the insect and on any species. Regarding species of interest in forensic entomology, AFLP data are currently available for Phormia regina, Lucilia sericata, and Chrysomya megacephala (Picard & Wells, 2009, 2010; Bao & Wells, 2014). AFLP analysis of full sibship is a promising method for the detection of post-mortem relocation.

Many interesting ideas and examples can be found in the literature on wildlife genetic geographic origin assignment. DNA testing, which relies on the assignment of an unknown sample to its genetic population of origin, has become a widespread tool in wildlife forensic science. The excellent review by Ogden & Linacre (2015) provides not only examples and detailed methods of DNA testing, but also valuable consideration on its use in court. As noted in the review, the availability and quality of reference data are of paramount importance and are currently the main disincentive of the application of DNA-based methods in the field of forensic entomology.

Identification of human DNA

Another contribution of molecular analysis is the identification of human DNA in the digestive tract of the larvae. This method can be used to determine the genetic profile of the victim (Campobasso, Di Vella & Introna, 2001; Wells & Sperling, 2001; Benecke & Wells, 2002) and can be used as evidence in the absence of a cadaver (Gaudry et al., 2007). Indeed, the presence of necrophagous larvae or pupae in an otherwise barren location can suggest the former presence of a cadaver. If genetic analysis of the gut contents of larvae reveals the victim’s DNA, entomological evidence can be used to infer relocation (Wells et al., 2001; Lohr, 2011). In 2001, Wells et al. showed that mitochondrial DNA sequences can be obtained from the dissected gut of a maggot that had fed on human tissue. In Chavez-Briones et al. (2013) reported the first forensic case of victim identification from human DNA isolated from the gastrointestinal tract of necrophagous larvae. Njau et al. (2016) showed that DNA analysis could be used to determine whether the larvae sampled on a cadaver were introduced from an alternative food source (e.g., a dead animal or a trash can near the cadaver). However, due to the rapid degradation of DNA by gut digestive enzymes, such analyses are limited to two days post-feeding (Picard & Wells, 2009; Charabidze, Hedouin & Gosset, 2013). Such restriction may change in a near future: a recent paper by Pilli et al. (2016) successfully used next generation sequencing to obtain a human profile from the gastrointestinal tract of head lice. Additionally more striking evidence of the potential of this method was provided by Marchetti et al. (2013) and Madra, Konwerski & Matuszewski (2014). They used short tandem repeat (STR) analysis to extract and type human DNA from empty puparia collected in two forensic cases. As puparia cases are highly durable, they offer a unique opportunity to indicate cadaver relocation a long time after the event.