Scanning electron microscopy in the identification of fly artifacts

Pelletti, Guido; Mazzotti, Matteo; Fais, Paolo; Martini, Désirèe; Ingrà, Laura; Amadasi, Alberto; Palazzo, Chiara; Falconi, Mirella; Pelotti, Susi

doi:10.1007/s00414-019-02090-5

Cited by 6 publications

(6 citation statements)

References 16 publications

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“…Moreover, FA did Reproduced the underlying texture of the fabric Edges (polyester) Linear, sometimes slightly scalloped Tail Absent or shorter than the body not present RBC, while on controls, the surface of the stain was paved by RBC. These results were in agreement with the features observed on FA deposited by S. carnaria on paper [10].…”

Section: Discussionsupporting

confidence: 92%

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Morphological characterization using scanning electron microscopy of fly artifacts deposited by Calliphora vomitoria (Diptera: Calliphoridae) on household materials

et al. 2021

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Insects found at a crime scene can produce traces referred to as fly artifacts (FA) due to their movement over the corpse and the manner in which they feed upon it. These can be detrimental for carrying out criminal investigations. Confusing a FA with a genuine bloodspot can lead to misinterpretations, also taking into consideration that FA may contain a human DNA profile. The aim of the present study was to employ scanning electron microscopy (SEM) for the analysis of FA produced by Calliphora vomitoria on hard surfaces and fabrics that are commonly present at crime scenes. FA and control bloodstains were produced under experimental conditions on metal, glass, plaster, cotton, and polyester. After macroscopic analysis, FA were examined at standard low (20–40 ×), medium low (300–600 ×), and high ultrastructural (1200 ×) magnification through a SEM Stereoscan 360, Leica, Cambridge. SEM analysis enabled the identification of distinctive features of FA on hard surfaces, namely, amorphous crystals, micro-crystals with a morphology similar to those of uric or micro-crystals with a comparable morphology to cholesterol, absent in controls. Moreover, red blood cells (RBC) were absent in FA but were always present in controls. On cotton, for both FA and controls, the drop was almost completely absorbed and thus indistinguishable from the underlying fabric texture. On polyester, FA showed amorphous/crystal-like deposits and no RBC, as observed on hard surfaces, except for those showing a completely flat surface. SEM analysis appeared to be suitable for differential diagnosis between FA and genuine bloodstains on hard surfaces, although the results may be inconclusive on tested fabrics.

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Section: Discussionsupporting

confidence: 92%

“…A recent study from our group showed that scanning electron microscopy (SEM) allows the visualization of ultrastructural morphological differences between FA deposited by Sarcophaga carnaria and blood controls on different types of paper -a promising tool for performing a differential diagnosis between FA and bloodstains [10].…”

Section: Introductionmentioning

confidence: 99%

Morphological characterization using scanning electron microscopy of fly artifacts deposited by Calliphora vomitoria (Diptera: Calliphoridae) on household materials

et al. 2021

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“…Toxicological data provided by the analysis of dark and light FA were kept separated and compared. Morphological aspects were not taken into consideration for this study [13][14][15].…”

Section: Toxicological and Statistical Data Analysismentioning

confidence: 99%

“…The purpose of this study is to understand if FA trace evidence permits toxicological analysis when traditional matrices are not available. To this aim, an ad-hoc crime scene was ideated and created on the base of authors' experience [13][14][15] and Calliphora vomitoria specimen were then artificially introduced for 2 days. FA were then carefully collected from absorptive and non-absorptive surfaces and analyzed for drugs of abuse.…”

Section: Introductionmentioning

confidence: 99%

The use of fly artifacts in a crime scene: Is there any application for forensic toxicology?

Giorgetti

Pelletti

Fais

et al. 2021

Journal of Forensic Sciences

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Fly artifacts (FA) are bloodstains resulting from insect activity at a crime scene, usually by feeding on human blood. Whether these artifactual stains might be useful for forensic toxicological investigations in cases of absence of conventional and unconventional matrices, for example, in cases concealment of the body or of extensive putrefaction, has not yet been investigated. The purpose of this study is to understand if FA trace evidence permits toxicological analysis when traditional matrices are not available. To this aim, FA experimentally produced by Calliphora vomitoria feeding on human blood of a cocaine and heroin user were collected from absorptive and non‐absorptive material. FA material was analyzed by a new simple and fast LC‐MS/MS method. Results were evaluated in terms of presence of the drug and relative amount of the detected molecules. From a qualitative point of view, the analysis of FA revealed all the substances originally detected in post‐mortem blood in both cases. The ratios of cocaine/benzoylecgonine, codeine/morphine, and 6‐monoacetylmorphine/morphine recovered in FA from cotton‐textile materials and from non‐absorptive surfaces were consistent with data resulted from original post‐mortem blood. The preliminary study herein reported demonstrated that FA are extremely informative in case of cocaine and heroin users and merit further research in order to be applied in real caseworks.

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“…As reported in Pelletti et al [9], Scanning Electron Microscopy (SEM) allows the visualization of morphological differences between fly artifacts deposited by Sarcophaga carnaria and blood controls, resulting in a suitable tool to perform a qualitative differential diagnosis between fly artifacts and bloodstain under experimental condition.…”

Section: Introductionmentioning

confidence: 99%

A DNA-based method for distinction of fly artifacts from human bloodstains

et al. 2021

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Fly artifacts resulting from insect activity could act as confounding factors on a crime scene and interfere with bloodstain pattern analysis interpretation. Several techniques have been proposed to distinguish fly artifacts from human bloodstains based on morphological approach and immunological assay, but a DNA-based method has not been developed so far. Even if in forensic genetic investigations the detection of human DNA is generally the primary goal, fly artifacts can provide useful information on the dynamics of crime events. The present study provides a molecular method to detect fly DNA from artifacts deposited by Calliphora vomitoria after feeding on human blood through the analysis of the mitochondrial cytochrome oxidase gene subunit I (COI). Fly artifacts originated from digestive process and of different morphology spanning from red and brownish/light brown, circular and elliptical stains to artifacts with sperm-like tail or a tear-shaped body were collected. The COI amplification was successfully obtained in 94% of fly artifact samples. The method showed high sensitivity and reproducibility, and no human DNA contamination was observed, offering specificity for use in confirmatory test. This molecular approach permits the distinction of fly artifacts from genuine bloodstains and the identification of fly’s species through the COI region sequencing by protocols usually applied in forensic genetic laboratories.

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Scanning electron microscopy in the identification of fly artifacts

Cited by 6 publications

References 16 publications

Morphological characterization using scanning electron microscopy of fly artifacts deposited by Calliphora vomitoria (Diptera: Calliphoridae) on household materials

Morphological characterization using scanning electron microscopy of fly artifacts deposited by Calliphora vomitoria (Diptera: Calliphoridae) on household materials

The use of fly artifacts in a crime scene: Is there any application for forensic toxicology?

A DNA-based method for distinction of fly artifacts from human bloodstains

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