It is all about the insects: a retrospective on 20 years of forensic entomology highlights the importance of insects in legal investigations

Abstract

This study highlights the importance of insect evidence by evaluating 949 insect-associated cases, including 139 entomological reports, from 2001 to 2019 at the Institute of Legal Medicine Frankfurt/Germany. With a high number of cases in the summer months and a low number in the colder season, 78.5% of the bodies were found indoors, regardless of year or month. In more than 80% of the cases, where PMI information was available (n = 704), the presumed PMI ranged from 1 to 21 days, a period during which entomological evidence can provide a day-specific estimate of PMImin. In cases where insects have been identified to species level (n = 279), most bodies were infested by one or two species with a maximum of 10 different species. Overall, a total of 55 insect species were found. Information on biology, activity and distribution of the most abundant taxa is given and applied for 5 case histories estimating different PMImins of up to over 6 months. Despite proved importance and scientific development of forensic entomology, insects are still rarely considered as a tool in forensic case work. The main reasons are a lack of awareness and (too) late involvement of a forensic entomologist. Our work shows that forensic entomology is an independent discipline that requires specialist expertise.

On the influence of environmental factors on the oviposition activity of necrophagous flies

“…For all species, except L. sericata, day of the year was the most or second most important variable influencing the oviposition activity, and all species showed species-specific seasonal adaptions. C. vicina had the widest seasonal niche, with ovipositions throughout the year, confirming it as a cold-adapted species with a year-round activity (Fremdt & Amendt, 2014;Lutz, Verhoff, et al, 2019;Samuel, 1997) and occurrence on human remains (Bernhardt et al, 2018;Lutz et al, 2021;Schröder et al, 2003). Our results classify L. ampullacea as a summer species, being highly active in June, July and August and absent from December until April.…”

Spatio-temporal distribution and habitat preference of necrophagous Calliphoridae based on 160 real cases from Switzerland

“…There were only 9 out of 51 cases (i.e., 18 %) found outdoor in Frankfurt [ 3 ], while we localized 58 out of 145 cases (i.e., 39 %) outdoor in and around Lausanne. The geographical distribution of P. regina and L. ampullacea in Europe during the years 1993–2007 could also be different from recent years due to climate change [ 27 , 35 , 36 ]. However, we think that the most probable reason might be the character of the local habitat composition and the topography of the compared areas.…”

“…These specific preferences of certain species can potentially bias such research and result in an under-or overestimation of abundance or even the presence of some of the focal species. Several studies focused on the distribution of blowflies using pig cadavers have already been published [21][22][23][24] and while such an approach is certainly more suitable (with pigs to be the most accurate option compared to human cadavers), there have not been many studies using the data of real cases to obtain such results [3,[25][26][27]. The reasons are probably (1) the size and time needed for obtaining a large enough dataset for making meaningful conclusions and (2) the legal complications stemming from the publication of such a sensitive dataset in some countries.…”

“…The real case data are also irreplaceable for elucidation of the ecology, colonization patterns and spatio-temporal distribution of blowflies for indoor cases. Indoor cases represent a large portion of the casework during medico-legal investigations [ 3 , 19 , 26 , 27 ]. Furthermore, indoor habitats have a completely different thermal dynamic in comparison to outdoor habitats and this dynamic differs based on local climatic conditions [ 19 , 22 ].…”

Biodiversity of Forensically Relevant Blowflies (Diptera: Calliphoridae) at the Anthropology Research Facility in Knoxville, Tennessee, USA

“…Information regarding insects associated with human remains often comes from casework, and is available for British Columbia [16], Hawaii [17], Texas [18,19], Indiana [20], and Italy [21]. Morgues and autopsies conducted at medical institutes can also provide information pertaining to the insects colonizing human remains [22][23][24][25][26][27][28]. Additionally, Matuszewski et al [29] conducted a global review of the forensic entomology literature pertaining to various animal models when examining whether swine carcasses were appropriate models for humans.…”