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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. Supplementary Information The online version contains supplementary material available at 10.1007/s00414-021-02643-7.

Empty puparia, as well as larvae at different developmental stages, are potentially useful in the identification of a victim where a corpse has been removed from the scene of a forensic investigation. To evaluate the relevance and the reliability of this substrate to be used as forensic evidence, the authors report for the first time the extraction and typing of human DNA from empty puparia using STR analysis, in two actual cases where the bodies of the victims were still present thereby enabling validation of the typing.

When a forensic DNA sample cannot be associated directly with a previously genotyped reference sample by standard short tandem repeat profiling, the investigation required for identifying perpetrators, victims, or missing persons can be both costly and time consuming. Here, we describe the outcome of a collaborative study using the Identitas Version 1 (v1) Forensic Chip, the first commercially available all-in-one tool dedicated to the concept of developing intelligence leads based on DNA. The chip allows parallel interrogation of 201,173 genome-wide autosomal, X-chromosomal, Y-chromosomal, and mitochondrial single nucleotide polymorphisms for inference of biogeographic ancestry, appearance, relatedness, and sex. The first assessment of the chip’s performance was carried out on 3,196 blinded DNA samples of varying quantities and qualities, covering a wide range of biogeographic origin and eye/hair coloration as well as variation in relatedness and sex. Overall, 95 % of the samples (N = 3,034) passed quality checks with an overall genotype call rate >90 % on variable numbers of available recorded trait information. Predictions of sex, direct match, and first to third degree relatedness were highly accurate. Chip-based predictions of biparental continental ancestry were on average ~94 % correct (further support provided by separately inferred patrilineal and matrilineal ancestry). Predictions of eye color were 85 % correct for brown and 70 % correct for blue eyes, and predictions of hair color were 72 % for brown, 63 % for blond, 58 % for black, and 48 % for red hair. From the 5 % of samples (N = 162) with

The use of insects to answer questions in criminal investigations, as well as a combination of forensic genetic techniques to obtain human DNA from the organisms, especially necrophagous dipterians, have gained ground in recent decades among researchers and professionals in this area. The objective of our study was to evaluate and compare two methods of human DNA extraction, commonly used for forensic samples, to obtain human autosomal DNA and X chromosome short tandem repeat profiles from the digestive tract of Chrysomya albiceps (Diptera: Calliphoridae) larvae. Immature specimens were collected from corpses at the Institute of Forensic Medicine of Pernambuco and raised in bovine ground meat to allow stabilization of the colony. Groups of larvae in the third instar were provided with bovine ground meat plus human blood for 48 h, dissected, and then subjected to DNA extraction. DNA was extracted using two methods: a DNA IQ™ kit and a phenol-chloroform method. Genomic DNA was amplified using AmpFℓSTR(®) Identifiler(®) Plus PCR and Argus-X-12(®) kits, and samples were sequenced to determine if the two extraction techniques generated reliable profiles that were compatible with a reference sample. The existence of comparable profiles from both techniques demonstrates the usefulness of dipteran larvae for obtaining human DNA from corpses, which can be further used to correlate genetic profiles in a crime scene when other traces are not available. However, several variables still require revision; thus, the technique should be further investigated for its validity, security, and, in particular, its reproducibility.

Criminal traces commonly found at crime scenes may present mixtures from two or more individuals. The scene of the crime is important for the collection of various types of traces in order to find the perpetrator of the crime. Thus, we propose that hematophagous mosquitoes found at crime scenes can be used to perform genetic testing of human blood and aid in suspect investigation. The aim of the study was to obtain a single Aedes aegypti mosquito profile from a human DNA mixture containing genetic materials of four individuals. We also determined the effect of blood acquisition time by setting time intervals of 24, 48, and 72 h after the blood meal. STR loci and amelogenin were analyzed, and the results showed that human DNA profiles could be obtained from hematophagous mosquitos at 24 h following the blood meal. It is possible that hematophagous mosquitoes can be used as biological remains at the scene of the crime, and can be used to detect human DNA profiles of up to four individuals.

Requests for solving complex kinship casework involving at least one female are increasing and in these circumstances the analysis of X-chromosomal STR markers plays a relevant role. Actually, it is well known the superior statistical power of X-STRs compared to autosomal markers in solving relationship when two sisters or half-sisters are involved and none of parents is available, in maternity testing or in cases involving close relatives as alternative putative fathers. In addition, the possibility to amplify more loci simultaneously and the strategy based on the analysis of four linkage groups to obtain the X-haplotype provide a powerful and validated tool. Nevertheless, haplotypes frequency distribution in different populations is still needed for calculation of probabilities in relationship testing. Published haplotype frequencies from German population data are available, but in different caseworks we found unreported X-haplotypes. To enlarge the forensic X-chromosome database, we present haplotype frequencies and other parameter of forensic interest obtained from 200 anonymous DNA samples of unrelated Italian males for the four linkage groups included in the Investigator Argus X-12 kit. From the comparison of the Italian sample haplotype frequencies with other populations, significant genetic distances were found with Asian and African populations, but not with Europeans. Finally, casework examples of complex kinship analysis are presented.

Standard molecular techniques, with only a slight modification, are very useful in obtaining and interpreting the final results in the field of forensic genetic. Data obtained through such analysis are highly reliable and can be used as a very powerful tool that produces valuable results. However, success and swiftness of DNA typing of biological evidence either that found at a crime scene or used in disputed paternity testing, depends on the optimization of numerous factors. One of the most important and critical phases that ensures reliability of the whole procedure is the choice of the most suitable volume for the amplification protocol. Buccal swabs were collected from volunteers. DNA was extracted by Qiagen Dnaeasy™ Tissue Kit (Qiagen Co. 2001). PowerPlex 16 kit (Promega Corp., Madison, WI) was used to simultaneously amplify 15 STR loci by PCR. Amplification was carried out as described previously (Promega Corp. 2001). The tested total working reaction volumes were 5, 10 and 25μΡ The PCR amplification was carried out in PE Gene Amp PCR System Thermal Cycler (ABI, Foster City, CA). Amplification products were analyzed on an ABI PRISM 377 instrument (ABI, Foster City, CA) in 5% bisacrilamide gel. Amplification was generally successful for all the tested reaction volumes. Lower partial to complete DNA profiles ratio, the quality of obtained STR profiles, significantly reduced amount of reaction’s components give advantage to 5μ! reaction volume over other two tested volumes in this case.