Jordaens K.,Royal Museum for Central Africa |
Jordaens K.,University of Antwerp |
Sonet G.,Royal Belgian Institute Of Natural Sciences |
Richet R.,Grande Rue |
And 3 more authors.
International Journal of Legal Medicine | Year: 2013
The identification of species of the forensically important genus Sarcophaga is very difficult and requires strong taxonomic expertise. In this study, we sequenced the mitochondrial cytochrome c oxidase subunit I (COI) gene of 126 specimens of 56 W European Sarcophaga species and added GenBank data to our database to yield a total dataset of 270 COI sequences from 99 Sarcophaga species to evaluate the COI gene as a molecular diagnostic tool for species identification in this genus. Using two simple criteria (Best Match, BM and Best Close Match, BCM), we showed that the identification success using a mini-barcode region of 127 bp was very low (80.7-82.5 %) and the use of this region is not recommended as a species identifier. In contrast, identification success was very high using the standard barcode region (658 bp) or using the entire COI region (1,535 bp) (98.2-99.3 %). Yet, there was a low interspecific sequence divergence (<2 %) in six species groups so that for 16 out of the 99 species (nine of which are of forensic importance), the use of COI barcodes as species identifier should be done with care. For these species, additional markers will be necessary to achieve a 100 % identification success. We further illustrate how such reference databases can improve local reference databases for forensic entomologists. © 2012 Springer-Verlag.
Verscheure S.,National Institute of Criminalistics and Criminology |
Verscheure S.,University of Antwerp |
Backeljau T.,University of Antwerp |
Backeljau T.,Royal Belgian Institute Of Natural Sciences |
Desmyter S.,National Institute of Criminalistics and Criminology
Forensic Science International: Genetics | Year: 2014
A Belgian dog population sample and several population studies worldwide have confirmed that only a limited number of mtDNA control region haplotypes is observed in the majority of dogs. The high population frequency of these haplotypes negatively impacts both the exclusion probability of dog mtDNA analysis and the evidential value of a match with one of these haplotypes in casework. Variation within the mtDNA coding region was explored to improve the discrimination power of dog mtDNA analysis. In the current study, the entire mitochondrial genome of 161 dogs was sequenced applying a quality assured strategy and resulted in a total of 119 different mitochondrial genome sequences. Our research was focused on those dogs with the six most common control region haplotypes from a previous Belgian population study. We identified 33 informative SNPs that successfully divide the six most common control region haplotypes into 32 clusters of mitochondrial genome sequences. Determining the identity of these 33 polymorphic sites in addition to control region sequencing in case of a match with one of these 6 control region haplotypes could augment the exclusion probability of forensic dog mtDNA analysis from 92.5% to 97.5%. © 2014 Elsevier Ireland Ltd.
Fernandez M.D.M.R.,National Institute of Criminalistics and Criminology |
Samyn N.,National Institute of Criminalistics and Criminology
Journal of Analytical Toxicology | Year: 2011
A fast and selective ultra-performance liquid chromatography- tandem mass spectrometry (UPLC-MS-MS) method for the determination of amphetamines (amphetamine, methamphetamine, methylenedioxymethamphetamine, methylenedioxyamphetamine, methylenedioxyethylamphetamine, ephedrine, and p-methoxyamphetamine) in plasma has been developed and validated. Sample preparation was performed by liquid-liquid extraction using ethyl acetate. For optimized chromatographic performance with repeatable retention times, narrow and symmetrical peaks, and focusing all analytes at the column inlet, a gradient start, with acid mobile phase consisting of 0.1% formic acid and methanol was chosen. Positive electrospray ionization MS-MS detection was performed with two multiple reaction monitoring transitions for each analyte. Deuteriumlabeled internal standards were used for five of the analytes. The limit of detection was in the range 0.25-1.25 ng/mL, and the limit of quantification was fixed at the lowest calibrator of 2.5 ng/mL for all of the compounds. The RSD values of the intra- and interassay precision and accuracy were lower than 11% at four concentration levels, including two external quality controls. No or only minor matrix effects were observed, and the extraction method presented recoveries higher than 93% for all the compounds. Total run time, including equilibration, was 12 min. The method is routinely used at the National Institute of Criminalistics and Criminology for quantitative determination of the main amphetamines in plasma from forensic and driving under the influence cases.
Desmyter S.,National Institute of Criminalistics and Criminology |
Gijsbers L.,National Institute of Criminalistics and Criminology |
Gijsbers L.,University of Amsterdam
Forensic Science International: Genetics | Year: 2012
In canine population studies for forensics, the mitochondrial DNA is profiled by sequencing the two hyper variable regions, HV1 and HV2 of the control region. In a first effort to create a Belgian population database some samples showed partially poor sequence quality. We demonstrated that a nuclear pseudogene was co-amplified with the mtDNA control region. Using a new combination of primers this adverse result was no longer observed and sequencing quality was improved. All former samples with poor sequence data were reanalyzed. Furthermore, the forensic canine population study was extended to 208 breed and mixed dogs. In total, 58 haplotypes were identified, resulting in an exclusion capacity of 0.92. The profile distribution of the Belgian population sample was not significantly different from those observed in population studies of three other countries. In addition to the total population study 107 Belgian registered pedigree dogs of six breeds were profiled. Per breed, the obtained haplotypes were supplemented with those from population and purebred studies. The combined data revealed that some haplotypes were more or less prominent present in particular dog breeds. The statistically significant differences in haplotype distribution between breeds and population sample can have consequences on mtDNA databasing and matching probabilities in forensics. © 2011 Elsevier Ireland Ltd. All rights reserved.
De Bock J.,National Institute of Criminalistics and Criminology |
De Smet P.,National Institute of Criminalistics and Criminology
IEEE Transactions on Information Forensics and Security | Year: 2016
In this paper, we present a new tool for forensic recovery of single and multi-fragment JPEG/JFIF data files. First, we discuss the basic design and the technical methods composing our proposed data carving algorithm. Next, we compare the performance of our method with the well-known Adroit Photo Forensics (APF) state-of-the art tool. This comparison is centered on both the carving results as well as the obtained data processing speed, and is evaluated in terms of the results that can be obtained for several well-known reference data sets. Important to note is that we specifically focus on the fundamental recovery and fragment matching performance of the tools by forcing them to use various assumed cluster sizes. We show that on all accounts our new tool can significantly outperform APF. This improvement in data processing speed and carving results can be mostly attributed to novel methods to iterate and reduce the data search space and to a novel parameterless method to determine the end of a fragment based on the pixel data. Finally, we discuss several options for future research. © 2015 IEEE.