STR typing of human DNA from fly larvae fed on decomposing bodies

In homicides with entomological evidence, it may be important to prove the presumed association of fly larvae to a corpse, especially if it is in doubt whether all maggots used for entomological expertise developed and fed on it. The present study demonstrates for the first time the possibility of analyzing human microsatellite DNA present in the digestive tract of necrophagous larvae that fed on decomposed bodies with a postmortem interval up to four months. The obtained human STR profiles support the association of a maggot to a specific corpse. In addition, the identification of the host species (e.g., animal source like pig) can be achieved by analysis of the cytochrome b gene. Maggots were collected from 13 corpses after various postmortem intervals and STR typing and HVR amplifications were performed using their crop contents. In seven cases, a complete STR profile was established, in two cases, an incomplete set of alleles was obtained, and in four cases, STR typing was not successful. HVR analysis was successful in all cases except one. The time of storage of the maggots and the length of the postmortem interval up to 16 weeks appeared to have no particular influence on the quality of the results.     

STR and SNP analysis of human DNA from Lucilia sericata larvae's gut contents

Importance of forensic entomology becomes inevitable when come across some incident where corpse is unidentifiable and lot of maggots or other insects are present. The most common application of forensic entomology is to use insects for the identification of specimens or human remains. DNA analysis recovered from a larva's gut contents can be used to identify a missing body. The obtained human STR and SNP profile support the association of a maggot to a specific patients or corpse. Main aim of this research was the identification of human DNA from gut contents of third instar maggots (larvae of Lucilia sericata) placed on diabetic patient's wounds for treatment purpose. Maggots (8–15) were taken from each diabetic patients (no. of the patients 8) and DNA was extracted from the gut contents manually by using Qiagen tissue protocol. Agarose gel electrophoresis was performed and the total size of DNA was seen using UV transilluminator. PCR amplification, STRs and SNPs profiling was then performed using PCR 9700 and AmpFLSTR Identifiler and SnaPshot Multiplex Kit (Applied Biosystems) respectively. The results were analyzed on ABI 310. SNP profiles were good and identifiable compared to the STRs where amplification was poor and the peaks were low. This may be the fact of the enzymatic activity present in the gut of the larvae which cause tremendous reduction in DNA size and thus yield. The results of this study reveals that it is possible to obtain a complete human profile using STRs and SNPs even if DNA is recovered from gut contents of maggots.     

Combined Statistical Analyses of Forensic Evidence in Sexual Assault: A Case Report and Brief Review of the Literature

DNA analysis has been widely used in the forensic field in order to contribute to identifying the perpetrator of a crime. Forensic investigation in sexual assaults usually focuses on locating and identifying biological fluids, followed by DNA analysis. The identification of certain compounds present in condoms can be useful to reconstruct the occurred event, especially in cases of sexual assaults where the DNA analysis did not show the presence of a male profile and where RNA analysis did not show the presence of sperm markers. Herein we describe the case of a woman reporting to be victim of sexual assault, who was not able to provide accurate information concerning the dynamics of the event; she remembered only forced penile–vaginal penetration by a single perpetrator. We performed short tandem repeat (STR) analyses and mRNA typing for forensic genetics testing on vaginal and rectal swabs collected on the victim, and Fourier-transform infrared spectroscopy (FTIR) followed by chromatographic analyses for the detection of condom compounds on the same swabs. The STR analysis showed only the victim’s genetic profile, and RNA analysis showed only the presence of vaginal and skin markers. In this situation, the identification of condom compounds residues on vaginal swabs became important as it complemented other collected evidences allowing the Court to reconstruct the events. A proposal of likelihood ratio (LR) calculation for the assessment of the weight of evidence in this case is described.     

The First Successful Use of a Low Stringency Familial Match in a French Criminal Investigation

We describe how a very simple application of familial searching resolved a decade‐old, high‐profile rape/murder in France. This was the first use of familial searching in a criminal case using the French STR DNA database, which contains approximately 1,800,000 profiles. When an unknown forensic profile (18 loci) was searched against the French arrestee/offender database using CODIS configured for a low stringency search, a single low stringency match was identified. This profile was attributed to the father of the man suspected to be the source of the semen recovered from the murder victim Elodie Kulik. The identification was confirmed using Y‐chromosome DNA from the putative father, an STR profile from the mother, and finally a tissue sample from the exhumed body of the man who left the semen. Because of this identification, the investigators are now pursuing possible co‐conspirators.     

Mitochondrial DNA and STR analyses of maggot crop contents: effect of specimen preservation technique

DNA analysis of maggot crop contents can be used to identify a missing body or aid entomologists with interpreting evidence used for PMI estimations. Entomological evidence is often collected and preserved to keep identifiable external features intact. The preservation methods currently in use may not be suitable for preserving DNA in the maggot crop for later analysis. In this study, carrion maggots raised on human tissue were preserved under the following 8 preservation conditions: no fluid at -70 degrees C, no fluid at 4 degrees C, no fluid at 24 degrees C, 70% ethanol at 4 degrees C, 70% ethanol at 24 degrees C, 95% ethanol at 24 degrees C, Kahle's solution at 24 degrees C and formaldehyde at 24 degrees C. Maggots were dissected following 2 weeks, 8 weeks and 6 months of preservation. The maggot crops were extracted, human DNA was quantitated, and an attempt was made at amplifying mitochondrial DNA (mtDNA) and short tandem repeat (STR) loci. Both mtDNA and STRs were successfully amplified from maggots stored in ethanol or without any preservation fluid. Formalin-containing preservation solutions reduced the recovery of DNA. The best results were observed from maggots stored without any preservation fluid at -70 degrees C.     

A Case of Insect Colonization Before the Death

Forensic entomology is a branch of forensic science in which insects are used as evidence in legal investigations relating to humans, domestic animals and wildlife. One of the theoretical pillars on which the discipline is based concerns the fact that flies colonize a body after death. However in cases of myiasis, maggots are present before death, with consequences in the correct estimation of the minimum postmortem interval (mPMI). We report here the case of a woman, largely colonized by fly larvae, who has lain alive in her garden for four days prior to being rescued. Larvae were found on the conjunctivae, the bronchi, the rectum and vagina. The woman's death, two months later, was caused by tetanus. The consequences of myiasis on mPMI estimation are here discussed. In fact, despite she was still alive larvae, indicated and estimated age of 1.5–2.5 days, based on environmental and body temperature.     

强奸致孕形成部分性葡萄胎的检验分析

目的探讨强奸致孕案葡萄胎组织的DNA检验和STR结果分析。方法用DNA Typer TM15试剂盒对犯罪嫌疑人、受害人血样和流产胚胎组织进行荧光复合STR基因座扩增检测。结果检测的一例流产胚胎组织DNA的STR峰谱表现出部分3条带,且3条带中有两个等位基因来源于犯罪嫌疑人,另外一个来源于受害人,推断为单卵双精子受精的部分性葡萄胎。结论应用STR分型技术可以推断葡萄胎的DNA来源和受精类型,为亲缘关系鉴定提供依据。     

The Successful Recovery of Low Copy Number and Degraded DNA from Bones Exposed to Seawater Suitable for Generating a DNA STR Profile

A universal method allowing for DNA profiling from bones exposed to seawater has not been reported yet. This study refers on the identification of a body immersed in seawater for 8 months. The biological material for identification was the mandibular body, usually characterized by low success rates of DNA analysis. Initially, two extraction protocols were performed with negative results: one used for bones immersed in fresh water and a silica‐column procedure. A third protocol was performed, which combined the extraction of a higher amount of bone powder, the use of multi‐silica‐based extraction columns followed by a concentration step. This protocol allowed to obtain low copy number DNA and to generate a 12‐loci STR profile by combining conventional STR typing and mini‐STR technologies. This protocol could be suitable when human bones have been exposed to severe environmental conditions, and the available nuclear DNA is highly degraded and in low copy number.     

Antemortem and Postmortem Nonapposite Data—A Multidisciplinary Identification Strategy

Identification of human remains is often achieved by comparing documented reference data with the same type of evidence obtained from the remains. We present a case of a decomposed unidentified body, whose identity was presumed but because of the low validity range of the available data, the identification process could not be completed. Antemortem radiographs of the teeth found in the house of the reputed victim could not be compared to the edentulous cadaver and the kinship between the victim and the only living relative that could provide DNA for comparison was too tenuous. Isolated teeth found at the scene, were neither a source of DNA reference information nor questioned data to be compared to the antemortem radiographs. The strategy implemented by the investigators to reallocate the status of the isolated teeth from the questioned source to the reference source of DNA to be compared with the cadaver is presented.     

Maggot-induced postmortem changes simulating gunshot wounds

In the warm season, human cadavers often are the breeding ground of fly larvae. In special conditions, the damage by maggots can take on the appearance of bullet holes. Preexisting injuries allow the maggots to penetrate the skin also in parts other than the body apertures commonly infested. Round tissue damage similar to gunshot-wounds are favored by the fact that the larvae of some types of flies bundle together to form feeding communities. The enzymes from the salivary glands of the fly larvae may in some rare instances even lead to perforation of bone lamellae (e.g. in the region of the orbital roofs). The case reports deal with 2 cases in which changes due to damage by maggots primarily gave the impression of gunshot-wounds.     

Three species of insects collected from an adult human corpse above 3300 m in elevation: a review of a case from Colorado

We report on the colonization of an adult human corpse by three insect species at 3350 m (11,000 ft) in elevation. The adult silphid Thanatophilus coloradensis (Wickham), adults of the blow fly Calliphora coloradensis (Hough), and larvae and adults of Lucilia silvarum (Meigen) were all collected from the victim's body which had been wrapped in plastic. The victim was found in late June in the Rocky Mountains of Colorado. This paper provides additional confirmation of the taxa utilizing a human corpse at high elevations in Colorado.     

Width as an alternative measurement to length for post-mortem interval estimations using Calliphora augur (Diptera: Calliphoridae) larvae

The length of fly larvae collected from corpses is often used to help provide an entomological estimate of time since death. However, 'head-curling' by larvae can affect the accuracy of length measurements. To investigate a possible resolution to this problem, larvae of Calliphora augur were grown on sheep's liver at two constant temperatures (20 and 25 degrees C). Replicate samples were collected at set time intervals until pupation. Body length and width were measured for individual larvae and examined as predictors of age. It was found that body width, as measured at the junction of the fifth and sixth abdominal segments, is comparable with body length for age prediction of maggots of C. augur grown at these temperatures. Furthermore, conversion of width to length can be done with 95% accuracy from a simple linear model.     

6+1STR试剂盒和电泳凝胶EX-Q20用于DNA快速检验

目的 建立快速个体识别STR分型方法.方法 取采集于FTA上的血样200份,经打孔仪取等量血痕分别使用6+1 STR试剂盒结合新型毛细管电泳凝胶EX-Q20进行快速电泳分析和使用SinofilerTM试剂盒结合POP4胶进行电泳分析,比较两者所耗费时间和结果的差异. 结果 6+1 STR试剂盒结合新型毛细管电泳凝胶能够...     

A forensic entomology case from the Amazon rain forest of Brazil

The first case of application of forensic entomology in the Brazilian Amazonia is described. The corpses of 26 men were found in the rainforest in Rondonia State, Brazil. Fly larvae collected on the bodies during autopsy were identified as Paralucilia fulvinota (Diptera, Calliphoridae). No data or specimens were collected at the crime scene. At the laboratory, the larvae developed into pupae in 58 h and into adults in 110.5 h. The total development time for P. fulvinota was measured in field experiments inside the forest. The age of the larvae when collected from the bodies was estimated as the difference between the time required for them to become adults and the total development time for this species. The estimated age of the maggots and the minimum postmortem interval was 5.7 days.     

Usefulness of dura mater in providing DNA samples for identifying cadavers

We examined the usefulness of the dura mater in identifying human remains. Dura mater was collected from 50 cadavers, including drowned, charred, and mummified remains. The STR genotype using the AmpFlSTR Identifiler Kit could be typed at 15 STR and amelogenin loci in 30 samples of 33 cases. Furthermore, the ABO genotype and amelogenin using gel-based methods could be typed in 44 samples of 50 cases. In cases with successful typing of STR, ABO-DNA, and amelogenin, the longest time after death was from 12 to 26 days in a drowned body. The minimum quantity of dura mater required for DNA extraction was about 2.5 mg, dried and fixed by ethanol, in a cadaver 15 h after death. The state of the DNA from the dura mater from the calvaria may be better than that from the basis cranii interna. We found that DNA from dura mater is one of the most useful samples for forensic identification.     

Analysis of Mitochondrial DNA from a Burned,Ninhydrin‐Treated Paper Towel

Contact‐based evidence is likely to have limited quantities of DNA and may yield mixed profiles due to preexisting or contaminating DNA. In a recent arson investigation, a paper towel was collected and used as circumstantial evidence. The paper towel was partially burned and was likely set on fire with flammable liquid. As part of the investigation, the paper towel was treated with ninhydrin to visualize fingerprint evidence. Initial DNA analysis of two swabs was negative for short tandem repeat (STR) markers and revealed a mixture of mitochondrial DNA (mtDNA). Analysis of 13 additional cuttings yielded four more mixed profiles, but also two samples with a common single‐source profile. The single‐source mtDNA profile matched that of the primary suspect in the case. Thus, even if initial mtDNA analysis yields a mixed profile, a sampling strategy involving multiple locations can improve the chance of obtaining valuable single‐source mtDNA profiles from compromised evidence in criminal casework.     

The identification of a dismembered human body: a multidisciplinary approach

A criminal case was directed to a multidisciplinary forensic team for identification, concerning a victim whose head, having two gunshot wounds, had been separated by a sharp instrument and was recovered 6 months later. The purpose of this research was to determine the sex and age of the victim for human identification. Primarily, macroscopic examination of the skull, tooth, and DNA analysis was conducted for sex determination. A rough assessment of age was made from the skull based on anthropological findings, however a more definitive result of age estimation was determined utilizing dental morphology. The dental data showed an age range of 32-37 from the mineral examination and the formulation of microscopic measurements. The results obtained from the skull and dental analysis matched with the physical characteristics of the victim's body, the known personal data of this person, and with the superposition of the photos gathered by a formal request. Besides, the result of DNA profiling of the victim showed male gender and direct relationship with the victim's presumed wife and daughter. Generally, research on human identification consists of sex and age determination. The sex characteristics can be precisely proved from DNA tests. However, age can be estimated by skeletal, and dental analysis. In this case the performed sex and age analysis lead the research to the selective matching of the missing person's identity.     

Caddisflies assist with homicide case: determining a postmortem submersion interval using aquatic insects

Although few indicators of time since death for corpses found in aquatic ecosystems are comparable in precision to the insect indicators used in terrestrial cases, there are observations that can be useful in suggesting or ruling out an approximate PMSI (postmortem submersion interval). For example, the time intervals required for certain growth phases of aquatic insects, such as caddisflies, that may attach themselves to the submerged remains can be used to estimate a minimum PMSI. Approximately 8 of the 13 orders of insects containing species with aquatic or semi-aquatic stages are likely to be associated with carrion or corpses in aquatic habitats. We present a case study in which portions of a body from an adult male were discovered in a south central Michigan stream. The body was dismembered and portions were recovered from two bags floating and submerged in the stream. Insect specimens collected from mesh and plastic bags consisted of one fly larva belonging to the family Muscidae, and caddisfly larvae belonging to two families: the Limnephilidae. (case-makers) and the Hydropsychidae, (net spinners). We used unique case-building behaviors of the limnephilid caddisflies found on the remains to elucidate a PMSI range consistent with the disappearance of the victim. It is important for forensic investigators to understand that although some precision is lost in estimating a PMSI with aquatic insects, these organisms should not be ignored in gathering evidence from aquatic crime scenes, and in fact, they can provide valuable details in estimating a PMSI.     

Human Identification by Oral Prosthesis Analysis with Probability Rates Higher than DNA Analysis

Several techniques are used to perform an appropriate and reliable human identification. Forensic dentistry has achieved great relevance over the past years. The aim of this article is to report the method used for the identification of a male body found in the colliquative stage of putrefaction. The identification of the victim was succeeded confronting the dental findings found in the corpse with the data present on dental records provided by his dentist. The major elements for the identity′s recognition were a metal core and a prosthetic crown that were being fabricated. These elements associated with the dental records were compelling for the elucidation of the case, and a positive body identification was achieved with high levels of probability. In the present case, cadaveric analysis of stomatognathic system structures achieved a probability value higher than DNA identification techniques, emphasizing the importance of forensic dentistry.     

DNA Recovery From Tape-Lifting Kits: Methodology and Practice

In the case of suspicious deaths, the technique of 1:1 taping is often used in Belgium. It consists of affixing a large number of adhesive tapes to the body of the victim. It is conventionally aimed at obtaining microtraces (e.g., fibers, hair) and is usually not used for DNA analysis. However, in some cases, DNA analysis of certain areas of interest identified on the 1:1 taping material can offer a last resort solution. The four-step method that is described in this article involves the selection of areas of interest on the body (Step 1), the selection of the corresponding tapes (Step 2), the decontamination of the tapes (Step 3), the selection of areas of interest on the tapes, for DNA sampling (Step 4). The method is illustrated by its successful application in four murder cases. In each case, DNA profiles of good quality could be identified, including profiles of persons different from the victim.