Human decomposition and the reliability of a ‘Universal’ model for post mortem interval estimations.
Forensic Sci Int. 2015 Aug;253:136.e1-9
Authors: Cockle DL, Bell LS
Human decomposition is a complex biological process driven by an array of variables which are not clearly understood. The medico-legal community have long been searching for a reliable method to establish the post-mortem interval (PMI) for those whose deaths have either been hidden, or gone un-noticed. To date, attempts to develop a PMI estimation method based on the state of the body either at the scene or at autopsy have been unsuccessful. One recent study has proposed that two simple formulae, based on the level of decomposition humidity and temperature, could be used to accurately calculate the PMI for bodies outside, on or under the surface worldwide. This study attempted to validate ‘Formula I’  (for bodies on the surface) using 42 Canadian cases with known PMIs. The results indicated that bodies exposed to warm temperatures consistently overestimated the known PMI by a large and inconsistent margin for Formula I estimations. And for bodies exposed to cold and freezing temperatures (less than 4°C), then the PMI was dramatically under estimated. The ability of ‘Formulae II’ to estimate the PMI for buried bodies was also examined using a set of 22 known Canadian burial cases. As these cases used in this study are retrospective, some of the data needed for Formula II was not available. The 4.6 value used in Formula II to represent the standard ratio of time that burial decelerates the rate of decomposition was examined. The average time taken to achieve each stage of decomposition both on, and under the surface was compared for the 118 known cases. It was found that the rate of decomposition was not consistent throughout all stages of decomposition. The rates of autolysis above and below the ground were equivalent with the buried cases staying in a state of putrefaction for a prolonged period of time. It is suggested that differences in temperature extremes and humidity levels between geographic regions may make it impractical to apply formulas developed in one region to any other region. These results also suggest that there are other variables, apart from temperature and humidity that may impact the rate of human decomposition. These variables, or complex of variables, are considered regionally specific. Neither of the Universal Formulae performed well, and our results do not support the proposition of Universality for PMI estimation.
PMID: 26092190 [PubMed – indexed for MEDLINE]
Study on the pupal morphogenesis of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae) for postmortem interval estimation.
Forensic Sci Int. 2015 Aug;253:88-93
Authors: Ma T, Huang J, Wang JF
Chrysomya rufifacies (Macquart) is one of the most common species of blow flies at the scene of death in Southern China. Pupae are useful in postmortem interval (PMI) estimation due to their sedentary nature and longer duration of association with the corpse. However, to determine the age of a pupa is more difficult than that of a larva, due to the fact that morphological changes are rarely visible during pupal development. In this study, eggs of C. rufifacies were reared in climatic chambers under four different constant temperatures (20, 24, 28 and 32°C each±1°C, respectively) with same rearing conditions such as foodstuff, substrate, photoperiod and relative humidity. Ten duplicate pupae were sampled at 8-h intervals from prepupae to emergence under the different constant temperatures, respectively. The pupae were sampled, killed, fixed, dissected and with the puparium removed, the external morphological changes of the pupae were observed, recorded and photographed. The morphological characters of C. rufifacies pupae were described. Based on the visible external morphological characters during pupal morphogenesis at 28°C±1°C, the developmental period of C. rufifacies was divided into nine developmental stages and recorded in detailed description. Based on above-mentioned nine developmental stages, some visible external morphological characters were selected as indications for developmental stages. These indications mapped to 8-h sampling intervals at the four different constant temperatures were also described in this study. It is demonstrated that generally the duration of each developmental stage of C. rufifacies pupae is inversely correlated to appropriate developmental temperatures. This study provides relatively systematic pupal developmental data of C. rufifacies for the estimation of PMI. In addition, further work may improve by focus on other environmental factors, histological analysis, more thorough external examination by shortening sampling intervals, PAE (the Pupal Age Estimator) method and parasitic insects of C. rufifacies.
PMID: 26112814 [PubMed – indexed for MEDLINE]
Using Computational Fluid Dynamics in the forensic analysis of a prison fire.
Forensic Sci Int. 2015 Aug;253:e33-42
Authors: Jahn W, Gonzalez O, de Dios Rivera J, Torero JL
On the 8th of December of 2010 a fire killed 81 inmates in a Chilean prison. While the collected evidence (including eye witness’ accounts) indicated an intentional fire, started by a group of inmates who were fighting against another group and who ignited a mattress and threw it over a bunk bed inside the cell, it could not be established how fast the fire grew and whether the prison guards acted promptly enough to prevent the tragedy. In this context, the public defender office in charge of the case requested an independent investigation in order to determine the approximated time the fire started, and the temperature evolution of the padlocks at the cell doors during the initial stage, based on the construction characteristics of the prison, the existing materials and the evidence collected during the investigation. Computational Fluid Dynamics (CFD) were used to analyse the movement of the smoke and to match the first appearance of smoke on CCTV recordings at locations away from the fire, allowing for the estimation of the time-line of events. The padlock temperatures as a result of hot gases from the fire was also simulated. It was shown that the fire grew quickly and became uncontrollable before the guards could intervene. By the time the guards arrived at the cells’ door, the padlocks were shown to be too hot to be handled without protection.
PMID: 26126497 [PubMed – indexed for MEDLINE]
Effect of Continuous and Cyclic Exposure to a Cold Environment on the Development of Larvae of Lucilia sericata (Diptera: Calliphoridae) in Different Sized Larval Masses.
J Med Entomol. 2016 Apr 25;
Authors: Magni PA, Dhaliwal SS, Dadour IR
Regulation of forensic practice in many countries prevents the pathologist performing an immediate autopsy. During the period prior to autopsy, the corpse and the insects possibly associated with it are stored in a mortuary with temperatures ∼4°C. When a corpse is found in a late stage of decay, fly immatures may be present as small or large larval masses. The purpose of refrigeration at 4°C is to slow down the decomposition of the corpse as well as the temporary disruption of the activity and development of the bacteria and the necrophagous insects associated with the corpse. The aim of this research is to investigate the growth and development of different larval masses of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae) when stored in a cold environment (4°C). The research was divided into experimental sessions comprising different storage conditions (continuous or cyclic exposure to a cold environment) for immature stages (second and third instar) and included four different sizes of larval mass (∼100, 500, 1,000, and 5,000 larvae) feeding on 4 kg of beef liver and replicated three times. Results show that if the larval mass has a size of ∼5,000 larvae, and the larvae have already reached third instar, then when they are exposed to a cold environment, their development continues. The storage condition at 4°C does not disrupt the development of such larvae. The number of larvae and their instar that make up the larval mass are essential data for the subsequent estimation of a correct minimum postmortem interval.
PMID: 27113109 [PubMed – as supplied by publisher]
Hyoid bone fusion and bone density across the lifespan: prediction of age and sex.
Forensic Sci Med Pathol. 2016 Apr 25;
Authors: Fisher E, Austin D, Werner HM, Chuang YJ, Bersu E, Vorperian HK
The hyoid bone supports the important functions of swallowing and speech. At birth, the hyoid bone consists of a central body and pairs of right and left lesser and greater cornua. Fusion of the greater cornua with the body normally occurs in adulthood, but may not occur at all in some individuals. The aim of this study was to quantify hyoid bone fusion across the lifespan, as well as assess developmental changes in hyoid bone density. Using a computed tomography imaging studies database, 136 hyoid bones (66 male, 70 female, ages 1-to-94) were examined. Fusion was ranked on each side and hyoid bones were classified into one of four fusion categories based on their bilateral ranks: bilateral distant non-fusion, bilateral non-fusion, partial or unilateral fusion, and bilateral fusion. Three-dimensional hyoid bone models were created and used to calculate bone density in Hounsfield units. Results showed a wide range of variability in the timing and degree of hyoid bone fusion, with a trend for bilateral non-fusion to decrease after age 20. Hyoid bone density was significantly lower in adult female scans than adult male scans and decreased with age in adulthood. In sex and age estimation models, bone density was a significant predictor of sex. Both fusion category and bone density were significant predictors of age group for adult females. This study provides a developmental baseline for understanding hyoid bone fusion and bone density in typically developing individuals. Findings have implications for the disciplines of forensics, anatomy, speech pathology, and anthropology.
PMID: 27114259 [PubMed – as supplied by publisher]
The juvenile face as a suitable age indicator in child pornography cases: a pilot study on the reliability of automated and visual estimation approaches.
Int J Legal Med. 2014 Sep;128(5):803-8
Authors: Ratnayake M, Obertová Z, Dose M, Gabriel P, Bröker HM, Brauckmann M, Barkus A, Rizgeliene R, Tutkuviene J, Ritz-Timme S, Marasciuolo L, Gibelli D, Cattaneo C
OBJECTIVE: In cases of suspected child pornography, the age of the victim represents a crucial factor for legal prosecution. The conventional methods for age estimation provide unreliable age estimates, particularly if teenage victims are concerned. In this pilot study, the potential of age estimation for screening purposes is explored for juvenile faces. In addition to a visual approach, an automated procedure is introduced, which has the ability to rapidly scan through large numbers of suspicious image data in order to trace juvenile faces.
METHODS: Age estimations were performed by experts, non-experts and the Demonstrator of a developed software on frontal facial images of 50 females aged 10-19 years from Germany, Italy, and Lithuania. To test the accuracy, the mean absolute error (MAE) between the estimates and the real ages was calculated for each examiner and the Demonstrator.
RESULTS: The Demonstrator achieved the lowest MAE (1.47 years) for the 50 test images. Decreased image quality had no significant impact on the performance and classification results. The experts delivered slightly less accurate MAE (1.63 years). Throughout the tested age range, both the manual and the automated approach led to reliable age estimates within the limits of natural biological variability.
CONCLUSIONS: The visual analysis of the face produces reasonably accurate age estimates up to the age of 18 years, which is the legally relevant age threshold for victims in cases of pedo-pornography. This approach can be applied in conjunction with the conventional methods for a preliminary age estimation of juveniles depicted on images.
PMID: 23728308 [PubMed – indexed for MEDLINE]
Age estimation of immature human skeletal remains from the diaphyseal length of the long bones in the postnatal period.
Int J Legal Med. 2014 Sep;128(5):809-24
Authors: Cardoso HF, Abrantes J, Humphrey LT
Age at death in immature human skeletal remains has been estimated from the diaphyseal length of the long bones, but few studies have actually been designed specifically for the purpose of age estimation and those which have, show important caveats. This study uses regression and classical calibration to model the relationship between age and diaphyseal length of the six long bones, in a sample of 184 known sex and age individuals (72 females and 112 males), younger than 13 years of age, selected from Portuguese and English skeletal collections. Age estimation models based on classical calibration were obtained for each of the six long bones, and separately for each sex and for the sexes combined, and also for the entire sample and when it is subdivided into two subsamples at the age of 2 years. Comparisons between inverse and classical calibration show there is a systematic bias in age estimations obtained from inverse calibration. In the classical calibration models, the length of the femur provides the most accurate estimates of age. Age estimates are more accurate for the male subsample and for individuals under the age of 2 years. These results and a test of previously published methods caution against inverse calibration as a technique for developing age estimation methods even from the immature skeleton. Age estimation methods developed using cemetery collections of identified human skeletons should not be uncritically applied to present-day populations from the same region since many populations have experienced dramatic secular trends in growth and adult height over the last century.
PMID: 24126574 [PubMed – indexed for MEDLINE]
Stature estimation from radiographic sternum length in a contemporary Spanish population.
Int J Legal Med. 2014 Sep;128(5):845-51
Authors: Macaluso PJ, Lucena J
The ability to estimate stature from various parts of the body is essential in medicolegal investigations, particularly in cases in which human remains have been dismembered or mutilated. Therefore, the aim of this study was to generate linear regression models for predicting stature on the basis of sternum length in contemporary Spaniards. Sternal length, or the combined length of the manubrium and mesosternum, was recorded from digital radiographs of the chest plate for 65 males and 52 females. Correlation coefficients for the regression models were r=0.391 and r=0.461 for the male and female formulae, respectively. The standard errors of the estimate were 6.20 cm for the male equation and 5.56 cm for the female equation. Given these relatively large standard error rates, the derived stature estimation models should only be used when other more accurate skeletal elements, such as intact long bones, are unavailable for analysis.
PMID: 24526040 [PubMed – indexed for MEDLINE]
Application of age estimation methods based on teeth eruption: how easy is Olze method to use?
Int J Legal Med. 2014 Sep;128(5):841-4
Authors: De Angelis D, Gibelli D, Merelli V, Botto M, Ventura F, Cattaneo C
The development of new methods for age estimation has become with time an urgent issue because of the increasing immigration, in order to estimate accurately the age of those subjects who lack valid identity documents. Methods of age estimation are divided in skeletal and dental ones, and among the latter, Olze’s method is one of the most recent, since it was introduced in 2010 with the aim to identify the legal age of 18 and 21 years by evaluating the different stages of development of the periodontal ligament of the third molars with closed root apices. The present study aims at verifying the applicability of the method to the daily forensic practice, with special focus on the interobserver repeatability. Olze’s method was applied by three different observers (two physicians and one dentist without a specific training in Olze’s method) to 61 orthopantomograms from subjects of mixed ethnicity aged between 16 and 51 years. The analysis took into consideration the lower third molars. The results provided by the different observers were then compared in order to verify the interobserver error. Results showed that interobserver error varies between 43 and 57 % for the right lower third molar (M48) and between 23 and 49 % for the left lower third molar (M38). Chi-square test did not show significant differences according to the side of teeth and type of professional figure. The results prove that Olze’s method is not easy to apply when used by not adequately trained personnel, because of an intrinsic interobserver error. Since it is however a crucial method in age determination, it should be used only by experienced observers after an intensive and specific training.
PMID: 24781787 [PubMed – indexed for MEDLINE]
Morphometric sex estimation from 3D computed tomography os coxae model and its validation in skeletal remains.
Int J Legal Med. 2014 Sep;128(5):879-88
Authors: Djorojevic M, Roldán C, García-Parra P, Alemán I, Botella M
In the last decade, the advances in imaging technologies have intensified the use of multislice computed tomography (MSCT) for anthropological purposes. The published literature has proved it to be a suitable tool for establishing sexually dimorphic characteristics in different anatomical areas. In this context, the main purpose of the present study was to explore the accuracy of traditional morphometric method when applied to data acquired in three-dimensional (3D) reconstructed os coxae of living Spanish population, to develop a series of statistically robust patterns for sex assessment and to test their validity in innominate remains. For this purpose, 150 volume-rendered innominate CT scans were selected to examine nine interlandmark linear distances by means of descriptive statistics and discriminant function analyses (DFA) employing the jackknife procedure for cross-validations. Five measurements were sexually dimorphic. Acetabular diameter was the single most accurate predictor. This, combined with innominate height and innominate breadth, contributed very significantly to sex estimation. Overall, classification accuracies were 89.3-95.3 % (89.3-94.7 % after cross-validation), with a sex-bias lower than 5 %. The second validation approach performed on a sample of 96 individuals from another contemporary Spanish reference collection comprising dry bones showed the high percentage of accurate classification (83.3-95.8 %). In conclusion, the assessment of sex using cross-sectional MSCT images of the os coxae is possible and the discriminant functions obtained on Spanish living individuals can also be effective for estimating sex from skeletal remains.
PMID: 24928326 [PubMed – indexed for MEDLINE]