A high performance liquid chromatography tandem mass spectrometry/mass spectrometry (HPLC-MS/MS) protocol was developed for the determination of diphenylamine (DPA). Four productions of DPA were selected for qualitative assay and the peak area of the main product ion for quantitation. By means of separation using an Agilent Extend-C18 column (CA, USA) (150 mm × 4.6 mm, 5 μm) with methanol-water (90:10) as the mobile phase, DPA was detected by electrospray ionization (ESI) tandem mass spectrometry in positive mode. The linearity of the peak area versus concentration ranged 5-500 ng/mL, r ² = 0.9978. The limit of detection (S/N =3) of this method was 0.3 ng/mL. This method is applicable for the determination of DPA in gunshot residue.

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This paper is concerned with the contribution of forensic science to the legal process by helping reduce uncertainty. Although it is now widely accepted that uncertainty should be handled by probability because it is a safeguard against incoherent proceedings, there remain diverging and conflicting views on how probability ought to be interpreted. This is exemplified by the proposals in scientific literature that call for procedures of probability computation that are referred to as "objective," suggesting that scientists ought to use them in their reporting to recipients of expert information. I find such proposals objectionable. They need to be viewed cautiously, essentially because ensuing probabilistic statements can be perceived as making forensic science prescriptive. A motivating example from the context of forensic DNA analysis will be chosen to illustrate this. As a main point, it shall be argued that such constraining suggestions can be avoided by interpreting probability as a measure of personal belief, that is, subjective probability. Invoking references to foundational literature from mathematical statistics and philosophy of science, the discussion will explore the consequences of this interdisciplinary viewpoint for the practice of forensic expert reporting. It will be emphasized that–as an operational interpretation of probability–the subjectivist perspective enables forensic science to add value to the legal process, in particular by avoiding inferential impasses to which other interpretations of probability may lead. Moreover, understanding probability from a subjective perspective can encourage participants in the legal process to take on more responsibility in matters regarding the coherent handling of uncertainty. This would assure more balanced interactions at the interface between science and the law. This, in turn, provides support for ongoing developments that can be called the "probabilization" of forensic science.

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Fentanyl, a powerful opioid analgesic introduced over 50 years ago, has a major role in modern anesthesia and chronic pain relief but has also gained a major role in illicit use. After a spike in fentanyl abuse between 2005 and 2007, fentanyl deaths decreased until 2010, with the introduction of “abuse-deterrent” OxyContin. Our data indicate a recent rise in fentanyl-related deaths beginning in 2013, which follows national trends. With the re-emergence of the synthetic narcotic analgesic of high potency as a popular drug of abuse and the alarmingly increasing mortality associated with its abuse, there are profound implications for public health, health care providers, law enforcement, and the society in general.

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Knives are among the weapons most frequently involved in criminal cases. They represent the most encountered category of weapons in Swiss homicide cases (completed and attempted homicides considered) and are also frequently employed in assault cases, notably bodily injuries. Whenever a knife is involved in a stabbing event, DNA and fingerprints may be sought. When garments are damaged, fibres can also be investigated. Fibres from the victim's garments might transfer onto the blade of the knife used in the assault and can thus provide useful information to determine whether a particular weapon could have be used to stab the victim. This study simulates vertical stabbings into garments with the use of a special holding device. Different types of knives and blades straight or serrated were used as weapons. Two garments presenting different shedding capacities and garment structures were also considered for the simulations. The distribution of fibres transferred onto the blade (number and position) was recorded for each simulation performed. Sequences of stabbings into the two garments were also carried out to assess whether the order of the stabs could be determined. Several parameters were considered, notably the distribution of fibres transferred onto the blade. The transfer of fibres inside the stab damage ballistic soap was used in this study and on the area near the second damage was also investigated. This study provides new insight into the interpretation of fibres transferred onto knives after a single stab or a sequence of stabbings and into determining the stabbing sequence. Finally, the study brings some guidelines for the search and recovery of fibres on the crime scene and on the blades of knives.

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The interpretation of the ethanol analysis results in postmortem cases may be challenging when the origin of postmortem ethanol (antemortem ingestion or microbial production) is under dispute. In this study, we investigated the suitability of blood 1-propanol cutoff concentration as a reliable marker for the discrimination between “positive” and “negative” for postmortem ethanol production (PEP) autopsy blood samples by performing receiver operating characteristic (ROC) analysis. The results indicated that a threshold 1-propanol concentration of 0.104 mg/dL had an area under the curve of 0.90 (standard deviation = 0.03), sensitivity of 79%, and specificity of 91% for predicting PEP with 95% confidence interval. This means that the positive for PEP autopsy blood samples yield significantly differentiated PEP than approximately 90% of the controls. The estimated concentration of 1-propanol is an applicable threshold (cutoff) value for autopsy blood 1-propanol to discriminate between “positive” and “negative” samples for PEP. We named this threshold 1-propanol concentration (of 0.104 mg/dL) as “1-propanol criterion.” In an effort to test its applicability to postmortem cases, we evaluated blood ethanol and 1-propanol from 222 postmortem cases records. The results showed that 10% of the tested samples were positive for PEP, and only a few of them were from bodies with signs of putrefaction at autopsy. This finding indicates that PEP in a corpse could take place before the appearance of obvious putrefaction. We suggest the ROC-based calculation of the 1-propanol cutoff concentration, at 0.104 mg/dL, as an effective method for “flagging” blood samples as positive for PEP irrespectively of the presence or not of putrefaction.

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Studies have shown that mental illnesses are more common among the prison population than the general population. However, most studies in this environment had only looked at nonspecific psychiatric morbidities. The objective of this study was to assess the prevalence of major depressive disorder, its associated sociodemographic and clinical variables in a population of inmates in Nigeria. Institution-based cross-sectional study was conducted among 196 prisoners consisting of 136 awaiting trials (AT) and 60 convicted inmates (CI). Simple random sampling technique was used to select the study participants. Data were collected using a structured interviewer-administered questionnaire. Depression was assessed with the depression module of the Structured Clinical Interview Schedule for Axis 1 Diagnostic Statistical Manual-IV (DSM-IV) Disorders. The diagnosis was made according to the DSM-IV criteria and severity assessed with the Montgomery–Asberg Depression Rating Scale (MADRS). Forty-one (30.1%) of AT compared with 21 (35.0%) of the CI were depressed. The mean total MADRS score for AT was 23.90 standard deviation (SD) ±7.97 while the mean total MADRS score for the convicted was 25.50 SD ± 8.70, P= 0.479. Unlike the general population, there were no sociodemographic predictors of depression. Among the ATs, depression was associated with the presence of physical complaints, having a chronic illness and family history of psychiatric illness among the CI. The prevalence of depression among prisoners was found to be high and associated with clinical variables. Due attention needs to be given to address the mental health needs of the prisoners.

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In the face of the era of big data, how to ensure the authenticity of electronic data has become an important practical issue. Online preservation methods based on hash operation, time stamp, and blockchain technology can effectively guarantee the authenticity and security of electronic data. Blockchains are inherently traceable, de-centralized, and difficult to tamper with, which can be enough served as the basic technology of electronic data certification. Preservation by blockchain mainly includes the following links: platform registration and identity authentication, generation and transmission of electronic data, and storage of electronic data. Preservation by blockchain has higher security than centralized online security because of distributed storage. However, it should be acknowledged that the preservation by blockchain is not without risk. The court should adhere to the principle of individual review of each case and review the electronic data from its generation, transmission, reception, storage, and collection.

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Reliability of expert testimony is one of the foundations of judicial justice. Both expert bias and scientific errors affect the reliability of expert opinion, which in turn affects the trustworthiness of the findings of fact in legal proceedings. Expert bias can be eliminated by replacing experts; however, it may be more difficult to eliminate scientific errors. From the perspective of statistics, errors in operation of forensic science include systematic errors, random errors, and gross errors. In general, process repetition and abiding by the standard ISO/IEC:17025: 2005, general requirements for the competence of testing and calibration laboratories, during operation are common measures used to reduce errors that originate from experts and equipment, respectively. For example, to reduce gross errors, the laboratory can ensure that a test is repeated several times by different experts. In applying for forensic principles and methods, the Federal Rules of Evidence 702 mandate that judges consider factors such as peer review, to ensure the reliability of the expert testimony. As the scientific principles and methods may not undergo professional review by specialists in a certain field, peer review serves as an exclusive standard. This study also examines two types of statistical errors. As false-positive errors involve a higher possibility of an unfair decision-making, they should receive more attention than false-negative errors.

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A criminal investigation requires the forensic scientist to search and to interpret vestiges of a criminal act that happened in the past. The forensic scientist is one of the many stakeholders who take part in the information quest within the criminal justice system. She reads the investigation scene in search of physical traces that should enable her to tell the story of the offense/crime that allegedly occurred. The challenge for any investigator is to detect and recognize relevant physical traces in order to provide clues for investigation and intelligence purposes, and that will constitute sound and relevant evidence for the court. This article shows how important it is to consider the relevancy of physical traces from the beginning of the investigation and what might influence the evaluation process. The exchange and management of information between the investigation stakeholders are important. Relevancy is a dimension that needs to be understood from the standpoints of law enforcement personnel and forensic scientists with the aim of strengthening investigation and ultimately the overall judicial process.

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A criminal investigation requires the forensic scientist to search and to interpret vestiges of a criminal act that happened in the past. The forensic scientist is one of the many stakeholders who take part in the information quest within the criminal justice system. She reads the investigation scene in search of physical traces that should enable her to tell the story of the offense/crime that allegedly occurred. The challenge for any investigator is to detect and recognize relevant physical traces in order to provide clues for investigation and intelligence purposes, and that will constitute sound and relevant evidence for the court. This article shows how important it is to consider the relevancy of physical traces from the beginning of the investigation and what might influence the evaluation process. The exchange and management of information between the investigation stakeholders are important. Relevancy is a dimension that needs to be understood from the standpoints of law enforcement personnel and forensic scientists with the aim of strengthening investigation and ultimately the overall judicial process.

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Human and animal hairs have been used in forensic investigations for over a century. Hair is stable under adverse natural conditions; hence, it is often recovered at the crime scene, and it is necessary to determine whether the hair is of human or animal origin. Morphological and genetic characteristics are useful to differentiate human hair from animal hair. In the present study, we analyzed the distinguishing characteristics of hair of various species. In addition, we explore species identification by cytochrome c oxidase I mitochondrial gene analysis. We confirm that both the microscopic and molecular analyses of hairs are useful in forensic investigations.

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Carfentanil, an ultrapotent analog of fentanyl, has invaded the street drug market, unbeknownst to many heroin users. About 10,000 times more potent than morphine, it was initially suspected that 20 μg of the substance was lethal. In this case series, we present 17 confirmed carfentanil overdoses in Michigan, with a primary focus on the concentration levels. Through a retrospective review, each public death reported in Oakland County, Michigan, with a subsequent toxicology report was investigated for suspected carfentanil use. To characterize each fatality, the autopsy results were collected, including the postmortem findings at scene and the decedent's medical and social history. Carfentanil levels were measured through liquid chromatography and tandem mass spectrometry (LC-MS-MS) by National Medical Services (NMS) Laboratories. Our case series found postmortem carfentanil concentrations as low as 10 ng/mL, with a mean concentration of 0.387 ng/mL. Ultimately, there are implications on law enforcement, first responders, and health care providers when dealing with this emerging illicit substance, and there is an alarmingly high mortality rate associated with the abuse of carfentanil.

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Today, in most of the countries forensic dental identification is considered as one of the most accurate and reliable method of identification of human remains. This application of forensic dentistry has proven successful in both single identification cases as well as in multiple fatality incidents such as world trade center disaster in 2001, the Asian tsunami in December 2004 etc. Comparative dental identification is one of the primary means of identification along with DNA and fingerprint analysis and also the most common method of identification of human remains. Identification of human remains from dental records is mandated by the law in some countries. India is one of the most disaster-prone countries of the world. It has had some of the world's most severe droughts, famines, earthquakes, road accidents, and rail accidents. In this paper, few multiple fatality incidents that took place over the last decade in India are reported. A brief analysis of all the reported cases and difficulties encountered during identification were discussed. The purpose of this paper is to discuss some of the issues involved in body identifications following disasters in India. The author also discussed to what extent Indian government is successful in utilizing the expertise of a forensic dentist in body identifications and also compared the present practice of forensic dental identification in India to Western countries. The goal is to cite situations and to bring issues into better focus, and hence that the identification procedures can be refined and changes can be made as necessary.

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Over the past few decades, age estimation of living persons has represented a challenging task for many forensic services worldwide. In general, the process for age estimation includes the observation of the degree of maturity reached by some physical attributes, such as dentition or several ossification centers. The estimated chronological age or the probability that an individual belongs to a meaningful class of ages is then obtained from the observed degree of maturity by means of various statistical methods. Among these methods, those developed in a Bayesian framework offer to users the possibility of coherently dealing with the uncertainty associated with age estimation and of assessing in a transparent and logical way the probability that an examined individual is younger or older than a given age threshold. Recently, a Bayesian network for age estimation has been presented in scientific literature; this kind of probabilistic graphical tool may facilitate the use of the probabilistic approach. Probabilities of interest in the network are assigned by means of transition analysis, a statistical parametric model, which links the chronological age and the degree of maturity by means of specific regression models, such as logit or probit models. Since different regression models can be employed in transition analysis, the aim of this paper is to study the influence of the model in the classification of individuals. The analysis was performed using a dataset related to the ossifications status of the medial clavicular epiphysis and results support that the classification of individuals is not dependent on the choice of the regression model.

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Estimation of postmortem interval (PMI) is vitally important in forensic investigations. Although many studies have examined the chemical changes of various tissues over time, no reports using spectroscopic methods in adipose tissue are available. In this study, attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy was utilized to collect comprehensive biochemical information from human adipose tissues in vitro at different times. Thereafter, mice were used as samples for in vivo experiments for more detailed studies on PMI. Then, partial least squares (PLS) model for PMI estimation was established based on the acquired spectral dataset of mouse samples. The spectral variable associated with C=O arising from lipids and free fatty acids was most susceptible to PMI. Moreover, the PLS model appeared to achieve a satisfactory prediction with a root mean square error of cross-validation of 1.78 days, and the reliability of the model was determined in an external validation set with a root mean square error of prediction of 1.87 days. The study shows the possibility of application of ATR–FTIR methods in PMI estimation using adipose tissue.

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Forensic odontology is a branch that connects dentistry and the legal profession. One of the members in the forensic investigation team is a dentist. Dentists play an important and significant role in various aspects of the identification of persons in various forensic circumstances. However, several dentists and legal professionals are quite ignorant of this fascinating aspect of forensic odontology. A need was felt to fill this gap. The dental record is a legal document possessed by the dentist and it contains subjective and objective information about the patient. A PubMed search and Google search were done for articles highlighting the importance of dental records in forensic sciences using the key words "forensic odontology, forensic dentistry, forensic dentists, identification, dental records, and dental chart". A total of 42 articles relevant to the title of the article were found and reviewed. The present article highlights the role of dentists in forensic sciences, their possible contributions to forensics, and the various aspects of forensic dentistry, thus bridging the gap of knowledge between the legal and the dental fraternities.

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This study evaluated the performance of the  Wuxi AGCU ScienTech Incorporation (HuiShan, Wuxi, China) AGCU Expressmarker 16 (EX 16) and 22 (EX22) short tandem repeat (STR) amplification kits in reduced reaction volumes using direct polymerase chain reaction (PCR) amplification workflows. The commercially available PowerPlex^® 21 (PP21) System (Promega, Wisconsin, USA), which follows similar direct workflows, was used as a reference. Anticoagulate blood applied to chemically impregnated  FTA ^TM Micro Cards (GE Healthcare UK Limited, Amersham Place, Little Chalfont, Buckinghamshire, HP7 9NA, UK) was used to represent a complex biological sample. Allelic concordance, first-pass success rate, average peak heights, heterozygous peak height ratios (HPHRs), and intracolor and intercolor peak height balance were determined. In reduced volume PCR reactions, the performances of both the EX16 and EX22 STR amplification kits were comparable to that of the PP21 System. The level of performance was maintained at PCR reaction volumes, which are 40% of that recommended. The EX22 and PP21 System kits possess comparable overlapping genome coverage. This study evaluated the performance of the AGCU EX16 and EX22 STR amplification kits in reduced PCR reaction volumes using direct workflows in combination with whole blood applied to FTA ^TM Micro Cards. Allelic concordance, first-pass success rate, average peak heights, HPHRs, and intracolor and intercolor peak height balance were determined. A concordance analysis was completed that compared the performance of the EX16 and EX22 kits using human blood applied to FTA Micro Cards in combination with full, half, and reduced PCR reaction volumes. The PP21 System (Promega) was used as a reference kit. Where appropriate, the distributions of data were assessed using the Shapiro-Wilk test. For normally-distributed data, statistics were calculated using analysis of variance (ANOVA) and for nonparametric data the Wilcoxon/Kruskal-Wallis test was used. Statistical significance was set at P < 0.05. Confidence intervals for mean values were set at 95%. On using reduced volume PCR reactions in combination with dried blood spots applied to FTA sample collection cards, both the EX16 and EX22 kits were shown to generate STR profiles of sufficient quality to allow entry into National DNA databases. The performance of both EX16 and EX22 was comparable to that of the PP21 System. This study demonstrates the successful use of the Wuxi AGCU ScienTech Incorporation EX16 and EX22 kits in reduced PCR reaction volumes with complex biological samples applied to chemically impregnated FTA sample collection cards.

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Accurate estimation of the postmortem interval (PMI) is an important task in forensic practice. In the last half-century, the use of postmortem biochemistry has become an important ancillary method in determining the time of death. The present study was carried out to determine the correlation between blood oxidation-reduction potential (ORP) values and PMIs, and to develop a three-dimensional surface equation to estimate the PMI under various temperature conditions. A total of 48 rabbits were placed into six groups and sacrificed by air embolism. Blood was obtained from the right ventricle of each rabbit, and specimens were stored at 10°C, 15°C, 20°C, 25°C, 30°C, and 35°C. At different PMIs (once every 4 h), the blood ORP values were measured using a PB-21 electrochemical analyzer. Statistical analysis and curve fitting of the data yielded cubic polynomial regression equations and a surface equation at different temperatures. Result: The results showed that there was a strong positive correlation between the blood ORP values at different temperatures and the PMI. This study provides another example of using a three-dimensional surface equation as a tool to estimate the PMI at various temperature conditions.

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Limited by the sensitivity of laboratory techniques, conventional human DNA analysis of touch DNA on frequently used items and prints does not always provide satisfactory results. In this study, microbiome DNA on personal computers, cell phones, and palm prints was analyzed and compared. After sample collection, DNA extraction, polymerase chain reaction amplification, library preparation, and sequencing, data were analyzed using the QIIME 1.8.0 software. Weighted unifrac distance between the right palm skin and the right side of a keyboard, the right palm skin and the mouse, and the left side of the keyboard and the left palm skin was 0.258850, 0.265474, and 0.214098, respectively. Even after palm prints were left for 1 week, microbial community structures were still quite similar to those of samples collected from the palm skin on the day they were left (weighted unifrac distance was 0.270885).

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A gold nanoparticle-enhanced surface plasmon resonance (SPR) aptasensor was developed for high-specificity and high-sensitivity detection of 2,4,6-trinitrotoluene (TNT). Self-assembly film-forming technology was used to modify the gold surface of the sensor chip with 2,4,6-trinitrophenyl glycine, a TNT analogue, using polyethylene glycol to which the thiol group and carboxyl group are attached. Aptamer-gold nanoparticle complexes were formed through Au-S bonding. To detect TNT, the samples were incubated with the aptamer-gold nanoparticle complexes, and the solution competition method was applied through the SPR aptasensor. The results showed that the SPR aptasensor achieved fast, real-time detection of TNT. This gold nanoparticle-enhanced SPR aptasensor is suitable for TNT detection in the field of public safety and environmental monitoring.

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Gas chromatography-mass spectrometry method was developed for the qualitative and quantitative analyses of chlorpyrifos in human blood samples. The chlorpyrifos and parathion (internal standard) in human blood were extracted with a mixed solvent of hexane and acetonitrile. Chlorpyrifos was well separated from the internal standard. The linear range of chlorpyrifos was 0.01–2 μg/ml in blood. The limit of detection and limit of quantification were estimated at 0.002 and 0.01 μg/ml, respectively. The inter- and intra-day precisions, accuracy, and recovery were assessed to verify this method. The results showed that the developed method is rapid, sensitive, and reliable. It is suitable for the determination of chlorpyrifos in forensic toxicological analysis and clinical diagnosis.

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Many new psychoactive substances (NPSs) with different chemical structures have emerged in the illicit drug market in the last decade. The present work was aimed at the development of a simple method in gas chromatography/mass spectrometry (MS) for the determination of NPS of different classes, the use of cannabinoids, and, at the same time, the evaluation of methadone therapy in hair matrix, within our routine analysis control for methadone treatment or from autopsy cases. The determination of synthetic cannabinoids and methadone therapy used an extraction method based on incubation in concentrated sodium hydroxide (NaOH) solution, providing a dissolution of the keratin matrix. The described method was applied on 15 authentic specimens from our cases: five showed the presence of methadone and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP). The described method can be useful not only in the forensic investigation of NPS-related addiction histories but also in epidemiological and retrospective studies on the spread of NPS among specific safety-sensitive social workers. The GC instrument was an Agilent 7820A (Agilent Technologies, Santa Clara, CA, USA), and the detection system was an Agilent 5977B single quadrupole MS operating in selective ion monitoring mode. Validation parameters such as limit of detections (LODs), limit of quantifications (LOQs), repeatability, accuracy, and linearity were satisfactory for its application on real specimens. LODs, LOQs, R%CV, standard deviation, and the mean concentration for the analyzed compounds are reported in Table 1b. Accuracy and repeatability were acceptable for all the analytes at their respective LOQs. Recovery experiments varied from 58.3% to 103.0%, thus allowing the application on authentic specimens. The described method can be useful not only in the forensic investigation of NPS-related addiction histories but also in epidemiological and retrospective studies on the spread of NPS among specific safety-sensitive social workers, such as drivers.

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The domain of forensic document examination consists of a variety of professional tasks related to the history and preliminary of questioned documents. The wide area of tasks implemented by forensic document examiners includes the skill to identify the authorship of handwriting and signature; discriminate among genuine, imitated, or disguised handwriting; to examine and analyze components of inks, papers, and other materials connected with documents; and other highly skilled analyses based on specialized technique. The field of handwriting examination is tightly related to empirical knowledge and practical experience. Handwriting is usually thought to be behavioral activities that are identifiable due to the appearance of features and characteristics within the writing. When we assess these features we universally analyze them in two aspects: Both quality and quantity of writing. As mentioned above, the evaluation of quality and quantity is performed by forensic document examiners. The problem is how to conduct this kind of evaluation related to empirical knowledge and experience. There is not consistent answer yet, although many researchers devote themselves to explore in this hot issue, such as mathematical methods applied in handwriting analysis. In this article, several mathematical methods applied to forensic document field are deciphered in domestic perspective of China. In the digital age, we all inevitably deal with problems with the help of computer or computer technology. We also pay close attention to the computer technique assistant in the field of forensic document examination. Standards or criteria of forensic document examination are still hot issues in China. Although we established a few standards or criterion based on requires of practice, it is also a lack of standards or criterion associated to trainees and continuing education in view of practitioners. At the end of this article, the author intends to discuss a piece of a challenge to forensic document examination, which are also universal issues abroad. Those who are critical of the current state of knowledge in this area argue that members of the judiciary have failed to sufficiently address the shortcomings of the forensic document evidence proffered in criminal trials. Specifically, critics of forensic document examination argue that little valuable wording exists in the report to support the validity and reliability of the methodology and findings of forensic document examination.

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Forensic image analysis has greatly developed with the proliferation of photography and video recording devices. Trace images of serious incidents are increasingly captured by first responders, witnesses, bystanders, or surveillance systems. Image perception is exposed with a special emphasis on the influence of the field of view on observation. In response to the pitfalls of the mental eye, a way to systematize the integration of images as traces in three-dimensional crime scene reconstruction is proposed. The systematic approach is based on the application of photogrammetric principles to slightly modify the usual photographic documentation as well as on the early collection and review of available trace images. The integration of images as traces provides valuable contributions to contextualize what happened at a crime scene based on the information that can be obtained from images. In a wider perspective, the systematic analysis of images fosters the use and interpretation of forensic evidence to complement witness statements in the criminal justice system. This article outlines the benefits of integrating trace images into a coherent reconstruction framework in order to improve interpretation of their content. A solution is proposed to integrate perception differences between the field of view of cameras and the human eye.

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We describe the optimization and validation of the DNATyper™15 multiplex polymerase chain reaction (PCR) genotyping system for autosomal short tandem repeat (STR) amplification at 14 autosomal loci (D6S1043, D21S11, D7S820, CSF1PO, D2S1338, D3S1358, D13S317, D8S1179, D16S539, Penta E, D5S818, vWA, D18S51, and FGA) and  amelogenin, a sex-determining locus. Several DNATyper™15 assay variables were optimized, including hot start Taq polymerase concentration, Taq polymerase activation time, magnesium concentration, primer concentration, annealing temperature, reaction volume, and cycle number. The performance of the assay was validated with respect to species specificity, sensitivity to template concentration, stability, accuracy, influence of the DNA extraction methods, and the ability to genotype the mixture samples. The performance of the DNATyper™15 system on casework samples was compared with that of two widely used STR amplification kits, Identifiler™ (Applied Biosystems, Carlsbad, CA, USA) and PowerPlex 16 ^® (Promega, Madison, WI, USA). The conditions for PCR-based DNATyper™15 genotyping were optimized. Contamination from forensically relevant nonhuman DNA was not found to impact genotyping results, and full profiles were generated for all the reactions containing ≥ 0.125 ng of DNA template. No significant difference in performance was observed even after the DNATyper™15 assay components were subjected to 20 freeze-thaw cycles. The performances of DNATyper™15, Identifiler™, and PowerPlex 16 ^® were comparable in terms of sensitivity and the ability to genotype the mixed samples and case-type samples, with the assays giving the same genotyping results for all the shared loci. The DNA extraction methods did not affect the performance of any of the systems. Our results demonstrate that the DNATyper™15 system is suitable for genotyping in both forensic DNA database work and case-type samples.

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