Developmental validation of the quantifiler real-time PCR kits for the quantification of human nuclear DNA samples

The Quantifiler Human DNA Quantification Kit and the Quantifiler Y Human Male DNA Quantification Kit were designed for the quantification of human genomic DNA in forensic samples. The kits use a real-time PCR-based process to quantify, respectively, total human DNA or human male DNA only. We report the results of a developmental validation study that we performed with the Quantifiler Kits, following the official SWGDAM guidelines. The Quantifiler Kits were tested for performance criteria such as species specificity, sensitivity, stability, precision and accuracy, and in addition, were tested with forensic case-type samples and mixed (male:female) DNA samples. The Quantifiler Kit methods were highly specific for human DNA, and could detect as little as 32 picograms of DNA using 2 microL of sample per assay. The accuracy and precision of the Quantifiler Kit methods was comparable or superior to that of other quantification methods.     

A Test of the Passalacqua Age at Death Estimation Method Using the Sacrum

A test of the accuracy of the Passalacqua (J Forensic Sci, 5, 2009, 255) sacrum method in a forensic context was performed on a sample of 153 individuals from the J.C.B. Grant Skeletal Collection. The Passalacqua (J Forensic Sci, 5, 2009, 255) method assesses seven traits of the sacrum using a 7‐digit coding system. An accuracy of 97.3% was achieved using the Passalacqua (J Forensic Sci, 5, 2009, 255) method to estimate adult skeletal age. On average each age estimate differed by 12.87 years from the known age. The method underestimated the age of individuals by an average of 4.3 years. An intra‐observer error of 6.6% suggests that the method can be performed with precision. Correlation and regression analysis found that the sacral traits used in the Passalacqua (J Forensic Sci, 5, 2009, 255) method did not have a strong relationship with age or an ability to strongly predict age. Overall, the method was not practical for use in a forensic context due to the broad age ranges, despite the high accuracy and low intra‐observer error.     

Sexual dimorphism in America: geometric morphometric analysis of the craniofacial region

One of the four pillars of the anthropological protocol is the estimation of sex. The protocol generally consists of linear metric analysis or visually assessing individual skeletal traits on the skull and pelvis based on an ordinal scale of 1-5, ranging from very masculine to very feminine. The morphologic traits are then some how averaged by the investigator to estimate sex. Some skulls may be misclassified because of apparent morphologic features that appear more or less robust due to size differences among individuals. The question of misclassification may be further exemplified in light of comparisons across populations that may differ not only in cranial robusticity but also in stature and general physique. The purpose of this study is to further examine the effect of size and sex on craniofacial shape among American populations to better understand the allometric foundation of skeletal traits currently used for sex estimation. Three-dimensional coordinates of 16 standard craniofacial landmarks were collected using a Microscribe-3DX digitizer. Data were collected for 118 American White and Black males and females from the W.M. Bass Donated Collection and the Forensic Data Bank. The MANCOVA procedure tested shape differences as a function of sex and size. Sex had a significant influence on shape for both American Whites (F = 2.90; d.f. = 19, 39; p > F = 0.0024) and Blacks (F = 2.81; d.f. = 19, 37; p > F = 0.0035), whereas size did not have a significant influence on shape in either Whites (F = 1.69; d.f. = 19, 39; p > F = 0.08) or Blacks (F = 1.09; d.f. = 19, 37; p > F = 0.40). Therefore, for each sex, individuals of various sizes were statistically the same shape. In other words, while significant differences were present between the size of males and females (males on average were larger), there was no size effect beyond that accounted for by sex differences in size. Moreover, the consistency between American groups is interesting as it suggests that population differences in sexual dimorphism may result more from human variation in size than allometric variation in craniofacial morphology.     

Nonmetric subadult skeletal sexing traits: I. A blind test of the accuracy of eight previously proposed methods using prehistoric known-sex mummies from northern Chile

While a number of nonmetric sex-related traits have been proposed, the accurate assignment of sex to subadult skeletal materials is generally considered problematic. Eight previously proposed nonmetric traits of the ilia and mandible have been demonstrated by other researchers to be related to the known-sex of subadults, yet there has been relatively little research attempting to evaluate the utility of these traits using independent collections of known-sex subadult skeletal remains. These eight traits include: elevation of the auricular surface, angle of the greater sciatic notch, depth of the greater sciatic notch, the "arch criteria," curvature of the iliac crest, gonial eversion, mandibular protrusion, and mandibular arcade shape. The present study blindly tested these eight nonmetric traits using 85 autopsied prehistoric known-sex mummified subadult remains from northern Chile that range in age between newborn and 15 skeletal years of age. The two primary questions examined for each trait are: (1) are the different character states for each of the eight traits related to known-sex, and (2) which of the eight traits are accurate enough for use in forensic cases? These questions are examined for each trait by both sex and age class so as to uncover potential sex- and age-related strengths and weaknesses for each of the characteristics. The results indicate that all eight of the previously proposed subadult sex-related traits are indeed related to known-sex, but that there is a great deal of variation by both sex and age in terms of the strength of congruent sex-related associations. With the exception of gonial eversion, all of the traits produced statistically significant chi2 values for their associations with known-sex when all subadult remains were considered. However, when all subadults are considered, only four traits demonstrated acceptable levels of accuracy for forensic applications. These traits include the arch criteria (82.3%), angle of the sciatic notch (80.7%), depth of the sciatic notch (79.0%), and mandibular arcade shape (77.6%). For subadults ranging in age from newborn to five skeletal years of age, only depth of the sciatic notch (81.5%) and the arch criteria (81.5%) approach acceptable levels of accuracy for use in forensic cases. The implications of these results are discussed and recommendations for bioarchaeological and forensic applications are made.     

Secular Change in Morphological Pelvic Traits used for Sex Estimation

This research evaluates secular change in Phenice's (Am J Phys Anthropol, 30, 1969 and 297) three morphological traits of the pubis, as described by Klales et al. (Am J Phys Anthropol, 149, 2012 and 104): medial aspect of the ischio‐pubic ramus, subpubic contour, and ventral arc. Ordinal scores were collected for these traits and compared between a sample of innominates from the historical Hamann–Todd Collection (n = 170) and modern Bass Donated Collection (n = 129). Using the Freeman–Halton test, significant differences between temporal sample score frequencies were found for all traits in females and for the subpubic contour and ventral arc in males. Despite these findings, classification accuracy using logistic regression between the temporal periods remained low (68.7%). These results suggest that secular changes in trait expression are occurring; however, sex estimation methods using these traits and created with historical samples are still applicable to modern forensic cases. In fact, the secular changes occurring in these traits contribute to better classification accuracy between sexes in modern populations.     

Determining the sex of human remains through cranial morphology

Sex determination is the keystone of a biological profile, yet few qualitative methods of cranial sex determination have been tested. This analysis examines the accuracy and precision of 17 morphological features of the skull commonly used to determine the sex of unknown skeletal remains. The sample consists of 46 identified skulls from the 19th century St. Thomas' Anglican Church Cemetery in Belleville, Canada. Nasal aperature, zygomatic extension, malar size/rugosity, and supraorbital ridge proved the most useful; of secondary value are chin form and nuchal crest; mastoid size is of tertiary consideration; nasal size and mandibular symphysis/ramus size rank fourth; forehead shape ranks fifth; and palate size/shape are sixth. Skull size/architecture provides an internal standard to assess the relative sizes of other traits. This research is a necessary step in establishing the credibility of morphological sex determination with respect to the Daubert and Mohan criteria for admissibility in a court of law.     

The distal humerus--a blind test of Rogers' sexing technique using a documented skeletal collection

Continuous monitoring of existing methods of skeletal diagnosis allows improving the reliability of personal identification in forensic and archaeological contexts. This study reports on a blind test re-evaluating the sexing technique proposed by Rogers (8) involving the distal humerus. A total of 351 humeri (184 male, 167 female specimens) from the documented skeletal assemblage of St. Bride's, London, was analyzed for the following traits: trochlear constriction, trochlear symmetry, olecranon fossa shape, and angle of the medial epicondyle. Individual traits showed substantial sex-discriminatory capacity, with "olecranon fossa shape" being most consistently accurate (84.6%) in predicting sex. The combination of all four traits provided an overall accuracy of 79.1%, including those individuals assessed as "probable" male and female. This renders the technique useful for forensic applications. The distal humerus can be recommended for sex assessment in addition to more established markers, especially since this part of the skeleton is frequently well preserved.     

Morphoscopic Trait Expression in “Hispanic” Populations

This study evaluates population variation of eight cranial morphoscopic traits using samples of known southwest Hispanics (n = 72), Guatemalans (n = 106), American Blacks (n = 146), and American Whites (n = 218). We applied the support vector machine (SVM) method to build a prediction model based on a subsample (20%) of the data; the remainder of the data was used as a test sample. The SVM approach effectively differentiated between the four groups with correct classification rates between 72% (Guatemalan group) and 94% (American Black group). However, when the Guatemalan and southwest Hispanic samples were pooled, the same model correctly classified all groups with a higher degree of accuracy (American Black = 96%; American White = 77%; and the pooled Hispanic sample = 91%). This study also identified significant differences between the two Hispanic groups in six of the eight traits using univariate statistical tests. These results speak to the unique population histories of these samples and the current use of the term “Hispanic” within forensic anthropology. Finally, we argue that the SVM can be used as a classification model for ancestry estimation in a forensic context and as a diagnostic tool may broaden the application of morphoscopic trait data for the assessment of ancestry.     

Sex Determination Using the Second Cervical Vertebra—A Test of the Method*

Abstract: Sex is one of the critical questions addressed when unidentified skeletal remains are discovered in forensic or archeological contexts. Continuous testing and re‐evaluation of existing techniques is essential to improve accuracy and precision. The Wescott (J Forensic Sci 2000; 45 (2):462–6) method of sex determination from dimensions of the second cervical vertebra was blind‐tested on 153 adult individuals from the Spitalfields documented collection of human skeletal remains held at the Natural History Museum, London. Significant sex differences were determined for all dimensions measured (independent two‐sample t‐test, p < 0.05–0.001). The discriminant functions developed by Wescott were shown to have an overall accuracy of classification of 76.99%. Using stepwise discriminant analysis, a discriminant function based on the Spitalfields data correctly classified sex in 83.3% of individuals and was able to classify males and females with equal accuracy. Additional discriminant functions are presented for use in instances where preservation of the second cervical vertebra is poor.     

A simple technique for age estimation in adult corpses: the two criteria dental method.

A method for age determination of adults from single rooted teeth is presented. It is based on the measurement of two dental features: periodontosis height times 100/root height (P) and transparency of the root height times 100/root height (T). These measurements are made on the labial surface of the entire tooth without section and do not require special equipment or training. The application of multiple regression analysis to a working sample of 306 teeth of known age, sex and race provided the following equation: Age (years) = 0.18 x P + 0.42 x T + 25.53. The mean error between the actual and estimated age was +/- 10 years on the working sample and +/- 8.4 years on a control sample made of 45 forensic science cases. Upper incisors showed a better precision than the other single rooted teeth and accuracy was not sex related. A comparison of the Gustafson and Lamendin methods on a control sample of 39 teeth resulted in an advantage of the latter considering the mean error on the estimation (14.2 +/- 3.4 years for Gustafson versus 8.9 +/- 2.2 for Lamendin). The Lamendin method can be practical interest for any forensic pathologist or dentist as it is fast, easy to use, and reasonably accurate except for cases of individuals under age 40 where other methods must be preferred.     

Nonmetric sex determination from the distal and posterior humerus in black and white South Africans

The successful identification of human skeletal remains relies on proven diagnostic techniques for sex determination. This research utilized 608 individuals from South Africa (420 men, 188 women) to conduct a blind nonmetric determination of sex from three features of the distal humerus: olecranon fossa shape, angle of the medial epicondyle, and trochlear extension. A scoring system between males and females was implemented, and the aggregate score of the three features determined the estimated sex of the skeletal element in question. With all features combined, black and white South Africans were categorized successfully as either male or female 75.5% (77% accuracy rate for females, 74% accuracy rate for males). This classification rate is lower than what was found in previous studies, but suggests that characteristics of the distal humerus are still quite valuable when estimating skeletal sex. More research is needed to assess reasons for the differential expression of these traits in different populations and to determine whether the method is nonpopulation specific.     

Self-reported personality traits in forensic populations: a meta-analysis

The current study covers a systematic review and meta-analysis of the prevalence of self-reported deviant or disruptive personality traits: anger, aggression, hostility, antisocial traits, psychopathy, and impulsivity in forensic populations worldwide. A computer-based search of titles was carried out using the PubMed electronic database for articles published in English that included a self-report instrument for personality characteristics in combination with a forensic population (i.e. detained in remand, sentenced and/or in enforced treatment, or on parole). The final sample consisted of 39 studies (N?=?11,716) that together used 17 different instruments and reported on 32 subscales or constructs that fitted our current interest. Results showed significantly higher levels of self-reported antisocial and psychopathic features in forensic samples, including a significant effect of the assessment instrument and subscale used. No significant differences were found for self-reported impulsivity, anger, aggression, or hostility in forensic populations compared to norm scores of non-forensic samples. Possible explanations, including suggestions that forensic populations are prone to providing socially desirable answers on self-report questionnaires, possibly to gain advantages such as a lower prison sentence or to avoid enforced treatment, are discussed, as well as limitations, and suggestions for future research and clinical practice.     

Validation of a radiographic method to establish new fetal growth standards: radio-anatomical correlation

In forensic medicine, specialists might face difficulties when estimating age at death from fetal remains. Depending on the state of preservation, this age assessment is essentially based on the diaphyseal size of long bones. In a previous work, for the measurement of fetal femoral ossified shafts, we already established a simple and reliable method using a radiographic protocol. Since we previously stated that radiographic measurement values were closer to real anatomical size than ultrasonographic ones, in the present study we decided to check the importance of the difference between radiographic and anatomical measurements. Therefore, we dissected 30 pairs of fetal femurs and compared the difference between the two kinds of measurements (in percentages). This difference seemed to be slight (4.027%), but it was large enough to entail significant differences (p < 0.001). In order to provide a correction factor for radiographic measurements, we established a linear regression formula, which was tested on another sample of 30 pairs of dissected femurs. As a consequence of the good results, we improved the linear regression using a powerful statistical tool: the bootstrap. Finally, we obtained a simple equation that allowed us to figure out the real anatomical size with an R2 of 99% and a mean relative difference of 0.153% (with a standard error of 0.252 mm, and therefore a 95% confidence interval with limits of -0.35 and 0.657 mm). This difference did not entail any significant differences (p = 0.498), and therefore, we concluded that with the proposed correction, radiographic measurements can easily be used by forensic specialists in their daily tasks or to establish new growth standards in order to best fit their population of interest.     

甲醛处理后人脊髓中的利多卡因和布比卡因的同时测定

目的建立经甲醛防腐处理后人脊髓中利多卡因和布比卡因同时定量测定的HPLC分析法,以满足法医学鉴定的需要。方法以空白人脊髓经甲醛防腐处理后添加标准利多卡因和布比卡因,对样品的前处理方法及仪器测试条件、方法的线性范围、检测限、精密度、回收率进行系统考察。结果所建方法中两药物的线性范围为0.5～10.0ug.g-1(利多卡因r=0.9999;Bupivacaine r=0.9998),检测限利多卡因为15ng布比卡因为20ng,日内、日间分析的相对标准偏差均在4.3％以内,加样回收率在97.3％～100.3％之间。结论经甲醛防腐处理后的脊髓可同时进行利多卡因和布比卡因定量测定。所建方法准确、实用,适用于法医学鉴定及相关研究。     

ID‐Check: Online Concealed Information Test Reveals True Identity

The Internet has already changed people's lives considerably and is likely to drastically change forensic research. We developed a web‐based test to reveal concealed autobiographical information. Initial studies identified a number of conditions that affect diagnostic efficiency. By combining these moderators, this study investigated the full potential of the online ID‐check. Participants (n = 101) tried to hide their identity and claimed a false identity in a reaction time‐based Concealed Information Test. Half of the participants were presented with personal details (e.g., first name, last name, birthday), whereas the others only saw irrelevant details. Results showed that participants′ true identity could be detected with high accuracy (AUC = 0.98; overall accuracy: 86–94%). Online memory detection can reliably and validly detect whether someone is hiding their true identity. This suggests that online memory detection might become a valuable tool for forensic applications.     

A Validation Study of the Langley et al. (2017) Decision Tree Model for Sex Estimation

Langley et al. (2017) developed a sex estimation decision tree utilizing two traditional cranial traits (glabella and mastoid) and a new trait: zygomatic extension. This study aimed to test the reliability of their zygomatic extension scoring method and validate their sex estimation method. Ordinal score data were collected from 281 male and female U.S. White and Black individuals. The five traditional cranial traits were collected from physical specimens, while zygomatic extension was scored from 3D cranial models. Intra‐ and interobserver analyses carried out on a subsample of 30 individuals indicate good agreement between zygomatic scores. The decision tree correctly sexed 71.5% of the sample, but a strong sex bias (94.2% correct for females, 49.3% correct for males) severely limits the utility of this method. The Walker (2008) and Stevenson et al. (2009) methods produced higher accuracy rates (80.8% and 82.6%, respectively), although these methods also produced sex and ancestry biases.     

Measuring the validity and reliability of forensic likelihood-ratio systems

There has been a great deal of concern recently about validity and reliability in forensic science. This paper reviews for a broad target audience metrics of validity and reliability (accuracy and precision) which have been applied in forensic voice comparison and which are potentially applicable in other branches of forensic science. The metric of validity is the log likelihood-ratio cost (C_llr), and the metric of reliability is an empirical estimate of credible intervals. A revised procedure for the calculation of credible intervals is introduced.     

Root Morphology and Anatomical Patterns in Forensic Dental Identification: A Comparison of Computer‐Aided Identification with Traditional Forensic Dental Identification*

Abstract: An online forensic dental identification exercise was conducted involving 24 antemortem–postmortem (AM–PM) dental radiograph pairs from actual forensic identification cases. Images had been digitally cropped to remove coronal tooth structure and dental restorations. Volunteer forensic odontologists were passively recruited to compare the AM–PM dental radiographs online and conclude identification status using the guidelines for identification from the American Board of Forensic Odontology. The mean accuracy rate for identification was 86.0% (standard deviation 9.2%). The same radiograph pairs were compared using a digital imaging software algorithm, which generated a normalized coefficient of similarity for each pair. Twenty of the radiograph pairs generated a mean accuracy of 85.0%. Four of the pairs could not be used to generate a coefficient of similarity. Receiver operator curve and area under the curve statistical analysis confirmed good discrimination abilities of both methods (online exercise = 0.978; UT‐ID index = 0.923) and Spearman’s rank correlation coefficient analysis (0.683) indicated good correlation between the results of both methods. Computer‐aided dental identification allows for an objective comparison of AM–PM radiographs and can be a useful tool to support a forensic dental identification conclusion.     

Validation of the Seratec® SeraQuant™ for the quantitation of prostate-specific antigen levels on immunochromatographic membranes

Abstract: Use of immunochromatographic membranes for the detection of prostate‐specific antigen (PSA) has become commonplace in forensic laboratories. Experiments were designed to test the newly developed Seratec^® SeraQuant? for accuracy, precision, and consistency in the quantitation of PSA. PSA standards were diluted with buffers and run on the instruments. Values obtained were examined for accuracy (was the correct value obtained?) and precision (were multiple sample values consistent?). To test for variation between instruments, large volumes of diluted PSA standard were run repeatedly on six units and the values obtained were plotted against the known PSA values to obtain a standard curve for each instrument. Fifty membranes having negative or weak positive results were then run on the six units, and the adjusted values were recorded and compared. Results of these experiments indicate that the instruments are accurate and precise in the quantitation of low levels of PSA.     

Discrete Traits of the Sternum and Ribs: A Useful Contribution to Identification in Forensic Anthropology and Medicine

During forensic anthropological investigation, biological profile is determined by age, sex, ancestry, and stature. However, several individuals may share the same profile. Observation of discrete traits can yield useful information and contribute to identification. This research establishes the frequency of discrete traits of the sternum and ribs in a modern population in southern France, using 500 computer tomography (CT) scans of individuals aged 15–60 years. Only discrete traits with a frequency lower than 10% according to the literature were considered, a total of eight traits. All scans examined were three‐dimensional (3D) volume renderings from DICOM images. In our population, the frequency of all the discrete traits was lower than 5%. None were associated with sex or age, with the exception of a single trait, the end of the xiphoid process. Our findings can usefully be applied for identification purposes in forensic anthropology and medicine.