Biological Evidence Management for DNA Analysis in Cases of Sexual Assault

Legal Decision-Making in an Adult Rape Case Involving DNA Evidence

This study investigated how jurors use deoxyribonucleic acid (DNA) evidence in an adult rape trial with a female victim and a male stranger defendant. Community members read a trial summary and then made case judgments (e.g., verdict). Results showed: (a) DNA evidence led to more pro-victim judgments (e.g., more guilty verdicts) than those who did not receive DNA evidence; (b) women were more pro-victim than men; (c) pro-victim judgments indirectly affected the presence of DNA evidence and verdict; and (d) the reason for a guilty verdict when DNA evidence was present typically noted a focus on the victim and DNA evidence.

Trends in forensic investigation of seminal fluid- a scoping review

In sexual assault cases, semen is the most significant evidence for investigation. It can be recovered from either the victim or the crime scene. Additionally, semen can also be retrieved along with other body fluids, which makes it even more difficult to detect. The detection methods for semen are very wide, ranging from conventional destructive techniques to modern nondestructive techniques. The conventional techniques are reliable but have great disadvantages in terms of specificity and evidence integrity. This review highlights recent investigative techniques that are currently trending in the detection of semen. It provides a comprehensive analysis of various methods, including a comparative evaluation of their effectiveness. Additionally, the review summarizes the use of DNA markers as a detection strategy.

The significance of prostate-specific antigen in forensic examinations of sexual violence: A case report

Prostate-specific antigen (PSA) tests are used in forensic science to perform rapid semen screening on vaginal swab samples from suspected victims of sexual assault. In some sexual assault cases, clothing or bedding is key evidence. A pre-trial investigation was launched following a complaint by an 85-year-old woman, who alleged that she had been raped by her 63-year-old son-in-law with whom she lives. Traces of seminal fluid were found in the vaginal swab (following a PSA test), and traces of seminal fluid, along with the victim's DNA and a partial DNA profile of the suspect, were found on the victim's underwear. The first-instance court (district court) found the man guilty and sentenced him to 3 years and 6 months of imprisonment for rape. Although PSA is produced in the prostate and secreted into seminal fluid, it is not exclusive to the prostate. PSA can be detected in women's bodies in various pathological conditions. In cases of sexual violence, the proper interpretation of laboratory tests is essential, taking into account all the circumstances of the incident as well as the victim's medical history.

Challenging biological samples and strategies for DNA extraction

Despite the significant progress of DNA profiling in forensic science, the extraction of DNA from challenging samples remains a formidable obstacle in forensic laboratories. Particularly, hard tissues (bones, teeth, hair, and nails), formalin-fixed tissues, and contaminated samples pose considerable difficulties. DNA extraction from such samples is often complicated, resulting in scanty, degraded, and contaminated DNA. Moreover, the presence of inhibitors from the surrounding environment further hinders DNA quantification and amplification, presenting additional challenges. This review article delves into the molecular basis of these challenges and examines the mechanistic principles underlying standard DNA extraction protocols. To overcome these obstacles, skilled efforts and additional pre-processing techniques are generally required before organic or silica column-based DNA extraction. Such techniques may involve scraping the waste, sample cleaning with detergents, disinfecting, demineralization of bones and teeth, long proteolytic enzyme treatment, in some cases, harsh methods like hot alkali treatment, tailored to the specific sample type. By addressing these challenges and understanding the molecular intricacies involved in DNA extraction, forensic scientists can improve the reliability and success rate of DNA analysis from difficult forensic samples. This review serves as a comprehensive resource for understanding the complexities of DNA extraction and offers potential solutions for recovering the DNA from highly challenging samples.

Valid and Reliable Attitude Scales for Measuring Clinician's Attitudes Towards Telehealth Assisted Sexual Assault Forensic Exams Using a Pre-Post Survey

The success of telehealth programs to guide clinicians to perform sexual assault medical forensic examinations relies on clinicians' positive attitudes toward telehealth services, though no validated tools to measure these variables exist. This study aims to report validity and reliability of a novel tool with two scales: Positive Beliefs and Acceptance scales for hospital nurse clinicians at sites initiating the Texas Teleforensic Remote Assistance Center (Tex-TRAC). An analysis of pre-post cross-sectional data of hospital nurse clinicians (N = 121) trained in the use of Tex-TRAC telehealth technology at seven participating hospitals in Texas from July 2022 to May 2023 was performed. The Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy and Bartlett's test of Sphericity sample size analysis were performed. Exploratory Factor Analysis (EFA) was applied for validity and internal consistency reliability Cronbach alpha (α) values were described for two scales: Positive Beliefs and Acceptance scales. Positive Beliefs scale has a KMO value of 0.810 and Barlett's test of sphericity (χ2 (6) = 380.47, P < .001). Acceptance scale has a KMO value of 0.832 and Barlett's test of sphericity (χ2 (28) = 432.19, P < .001). After Promax Oblique rotation, the final four-item Positive Beliefs scale had α = .894; the final five-item Acceptance scale had α = .876. Validity and reliability of both scales demonstrated potential usefulness for future telehealth interventions engaging Sexual Assault Nurse Examiners. Continued use of these scales could provide additional information that can be leveraged in training curriculum of similar telehealth programs like Tex-TRAC.

Toward Analysis at the Point of Need: A Digital Microfluidic Approach to Processing Multi-Source Sexual Assault Samples

Forensic case samples collected in sexual assaults typically contain DNA from multiple sources, which complicates short-tandem repeat (STR) profiling. These samples are typically sent to a laboratory to separate the DNA from sperm and non-sperm sources prior to analysis. Here, the automation and miniaturization of these steps using digital microfluidics (DMF) is reported, which may eventually enable processing sexual assault samples outside of the laboratory, at the point of need. When applied to vaginal swab samples collected up to 12 h post-coitus (PC), the new method identifies single-source (male) STR profiles. When applied to samples collected 24-72 h PC, the method identifies mixed STR profiles, suggesting room for improvement and/or potential for data deconvolution. In sum, an automated, miniaturized sample pre-processing method for separating the DNA contained in sexual assault samples is demonstrated. This type of automated processing using DMF, especially when combined with Rapid DNA Analysis, has the potential to be used for processing of sexual assault samples in hospitals, police offices, and other locations outside of the laboratory.

Forensic evidence preservation following an incident of rape: The role of the victim

BACKGROUND

Rape has a high prevalence in South Africa. The collection of credible and valid forensic evidence is a key legal factor that impacts case trial outcomes. Victim behaviour around the time of the rape can impact the collection and the integrity of forensic evidence, and can have a direct effect on case progression and conviction. Despite the importance of victim behaviour, few studies have been done on the role of victims in preserving forensic evidence. This article discusses how common personal hygiene practices undertaken by rape victims after being raped can impact the quality and validity of forensic evidence. This investigation was done with the aim of elucidating the role of victims in preserving forensic evidence post rape.

METHODS

This was a descriptive, retrospective clinical audit of all rape victims managed at Robert Mangaliso Sobukwe Hospital forensic unit in South Africa from 01 January 2020 to 31 March 2022.

RESULTS

A total of 192 rape cases over the study period were included in this review. The median age of rape victims was 20 years (minimum 2 years; maximum 76 years). The majority (n = 178; 92.7%) of the victims were female. About 44.8% (n = 86) of the victims reported that they had urinated post-rape and prior to forensic examination, 20.8% (n = 40) had changed their clothing, 8.3% (n = 16) had showered, 6.8% (n = 13) had bathed, 4.2% (n = 8) had douched, and only 1.0% (n = 2) had defecated. Only 44 (22.9%) of the victims reported to have ingested alcohol or spiked drinks before the rape.

CONCLUSION

These findings suggest that some rape victims engaged in personal hygiene practices that could militate against forensic evidence preservation. This finding, therefore, indicates the need for public awareness about ways to preserve evidence to the greatest extent possible after an incident of rape.Contribution: We provide simple guidelines for victims on the preservation of forensic evidence following rape and before detailed forensic medical examination and evidence collection.

The Effects of Victim Gender Identity, Juror Gender, and Judicial Instructions on Victim Blaming, Crime Severity Ratings, and Verdicts in Sexual Assault Trials

Transgender individuals may experience social discrimination and unfair legal considerations as crime victims. The current purpose was to investigate the relationship between the participant/jurors' gender, the victims' gender identity, and judge's instructions to ignore the gender identity of the victim on perceptions of the victim and the crime and verdicts rendered in a sexual assault case. Overall, crime severity ratings were significantly lower for the trans male victim compared to the cisgender female victim. Male participants reported lower crime severity ratings for trials involving transgender victims compared to cisgender victims. However, victim blaming, likelihood that the defendant committed the crime, sentencing recommendations, verdict confidence, and conviction rates did not vary by the victim's gender identity, the participant's gender identity, nor the judge's instructions. Participant gender as a predictor of verdict approached significance, indicating a trend for males to render more not guilty verdicts and females to render more guilty verdicts. In summary, male jurors perceived the crimes involving transgender victims as less severe and this may have impacted the rate of not guilty verdicts.

Recent advancements in identification and detection of saliva as forensic evidence: a review

Background

Saliva is the most common biological evidence found at any crime scene next to blood. It is a clear liquid which makes it immune to any possible evidence of alteration by the perpetrator. In forensics, saliva is used as biological evidence and is very helpful in determining various aspects of an individual such as sex, individuality, ABO blood groups, microbial signature, biomarkers, or habits like smoking.

Main body

Saliva shares a great resemblance with plasma as it encompasses similar organic or inorganic compound contents. In forensic casework, identifying any evidence is the primary goal to establish the groundwork for further investigation. Saliva may be found in the form of a pool or stained form, but its identification is challenging because of its transparency. It has been widely used as an informative tool in forensic situations like poisoning, hanging, or cases of drug abuse, etc. for more than two decades now. Over the years, many proposed ways or methods have been identified and described, which helped in the detection and identification of saliva as evidence.

Conclusion

This review article represents the significance of saliva as important forensic evidence, along with the different forms it may be encountered at the crime scene. The use of diverse collection and detection methods, over the past few decades, has been discussed. An attempt has been made to collect the available data, highlighting the merit and demerits of different identification techniques. The relevant data has been collected from all the published and reported literature (1987–2021).

The Chain of Custody in the Era of Modern Forensics: From the Classic Procedures for Gathering Evidence to the New Challenges Related to Digital Data

The purpose of this work is to renew the interest and attention for the chain of custody in forensic medicine, its establishment and maintenance, protecting the integrity and validity of evidence as well as to analyze how over time the establishment of the chain of custody and the collection of evidence has evolved also in function of the advent of technology and the use of electronic devices connected to the network. The analysis of the various aspects of the chain of custody demonstrates how necessary it is for the professional figures involved in the phases of the investigation (especially those who manage the evidence and who have, therefore, designated the assignment) to know the procedures to follow, trace the movement and the handling of objects subjected to seizure, also for the purposes of toxicological and/or histological investigations. The knowledge of interferences or complications helps to reduce errors and safeguard the validity of the evidence, assuring the proceeding judicial authority that the evidence is authentic and that it is, in other words, the same evidence seized at the scene of the crime. Furthermore, the issue is particularly felt today, with the recent need to guarantee the originality of digital data. Following a careful review and analysis of the literature currently available in this regard, it is worth adding that further efforts are needed to formulate internationally validated guidelines, harmonizing the different reference criteria in forensic science and medical areas, given the current absence of good international practices valid in the field and applicable both in the case of physical evidence and in the case of seizure of digital evidence.

Effect of machine-washing semen-stained fabrics on the persistence of human spermatozoa DNA: A systematic review of five articles

Biological evidence of sexual violence, such as semen, can change due to fabric washing. This can be due to attempts by the perpetrator to eliminate evidence or because the victim feels ashamed of sexual violence. While much research on this topic has been conducted, no systematic review has been attempted. This systematic review explores the effect of fabric machine-washing on the persistence of human spermatozoa deoxyribonucleic acid (DNA). This systematic review seeks in vitro experiments in which semen-stained fabrics were washed by washing machines, published in English, and matched with keywords in PubMed, Europe PMC, ScienceDirect, and Google Scholar. We then assessed the obtained articles with the Joanna Briggs Institute quasi-experimental checklist. This systematic review used the narrative synthesis method. Our search yielded five articles. These articles observe the effect of machine-washing factors on the persistence of human spermatozoa DNA, such as water temperature, washing duration, detergent type, washing repetition, and duration of fabric storage before washing. This systematic review shows that fabric washing insignificantly affects spermatozoa DNA persistence, and DNA might persist after multiple washes. However, variations in the articles indicate that future studies on this topic need to account for more variables and be reported in more detail to reduce bias.

Attenuated total reflection-Fourier transform infrared spectroscopy: a universal analytical technique with promising applications in forensic analyses

Contemporary criminal investigations are based on the statements made by the victim and the eyewitnesses. They also rely on the physical evidences found in the crime scene. These evidences, and more particularly biological ones, have a great judicial value in the courtroom. They are usually used to revoke the suspect's allegations and confirm or refute the statements made by the victim and the witnesses. Stains of body fluids are biological evidences highly sought by forensic investigators. In many criminal cases, the success of the investigation relies on the correct identification and classification of these stains. Therefore, the adoption of reliable and accurate forensic analytical methods seems to be of vital importance to attain this objective. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) is a modern and universal analytical technique capable of fingerprint recognition of the analyte using minimal amount of the test sample. The current systematic review aims to through light on the fundamentals of this technique and to illustrate its wide range of applications in forensic investigations. ATR-FTIR is a nondestructive technique which has demonstrated an exceptional efficiency in detecting, identifying and discriminating between stains of various types of body fluids usually encountered in crime scenes. The ATR-FTIR spectral data generated from bloodstains can be used to deduce a wealth of information related to the donor species, age, gender, and race. These data can also be exploited to discriminate between stains of different types of bloods including menstrual and peripheral bloods. In addition, ATR-FTIR has a great utility in the postmortem investigations. More particularly, in estimating the postmortem interval and diagnosing death caused by extreme weather conditions. It is also useful in diagnosing some ambiguous death causes such as fatal anaphylactic shock and diabetic ketoacidosis.

A multidisciplinary approach in pre-pubertal child sexual assault cases - forensic evaluation and suggestions

BACKGROUND

Child sexual assault is highly prevalent in India yet a handful cases are reported under POCSO (Protection against child sexual offenses) Act, 2012. Even though the victims' testimony alone is enough to arrest accused as regulated by the Supreme Court but forensic evidence is still critical for sentencing rapists. A systematic evaluation of such cases will estimate impact of Child sexual assault (CSA) and pinpoint important aspects required for progression of prevention strategies and provision of support.

METHOD AND OBJECTIVE

Present study reviewed cases pertaining pre-pubertal victims (up to 10 years age). Study included simple descriptive analysis of data highlighting significance of different variables in sexual assault cases involving child victims- perpetration, interventions, medical examination and forensic DNA analysis with the aim to improve primary preventive strategies and identify potential setbacks obstructing road to justice.

RESULT

The strengths and weaknesses of pre-pubertal sexual assault assessment were identified. This study analyzed socio-economic backgrounds, age of alleged accused and whether known to the victim. Frequently reported type of abuse was assessed and total reviewed cases that yielded DNA profile from exhibits of victims and alleged accused were determined.

CONCLUSION

As emerged in present study, pre-pubertal CSA is a complicated phenomenon grounded in interplay between societal influences, family support, evidence collection, legal delays, and medical hindrances that greatly affect DNA analysis. Prevalence of CSA is evidently alarming and demands stringent measures to be taken to prevent and control it. Joint and multidisciplinary assessment is important for forensic reporting rather than solo assessment.

Physical evidence of rape against children and adolescents in Brazil: Analysis of 13,870 reports of sexual assault in 2017

Introduction:

The medical literature reports child and adolescent maltreatment since the 8th century. Unfortunately, even today, the incomplete knowledge of this event persists. Several forms of violence are applied to children and adolescents, mainly sexual violence including rape and sexual assault. Forensic medical examinations routinely include the genital area, anus, and the body of the victims for signs of a recent or old injury. The main goal of this study is to show the results of physical and sexual examinations regarding confirmation of rape in children and adolescents, based on the medicolegal reports.

Methods:

We made a descriptive cross-sectional study conducted by collecting data from Medicolegal Institute (IML-São Paulo, Brazil) in 2017. We examined 13,870 reports of sexological examinations of victims of the alleged rape. The variables analyzed were age; sex; physical examination; sexological examination; and direct search for sperm in the vaginal, anal, or oral cavity. We selected 11,725 reports from victims under 18 years.

Results:

As for the medical-legal findings, only 1735 reports (14.8%) confirmed sexual abuse. The most affected ages were between 3 and 5 years in the male group and 11 to 14 years in the female group. The most frequent injuries were bruises and abrasions, fissures in the anal region. In 96.2% of the examined males and 85.8% of the females under 14 years old, the examination was inconclusive, and somebody cannot prove the alleged rape. Only 1735 reports (113 from men and 1622 from women) concluded beyond any doubt the alleged rape (14.8%). The search for sperm was positive in only 1582 cases (13.5%).

Conclusion:

This study shows that the results of the medicolegal examinations were quite limited in recording evidence. Sexual violence against children and adolescents reaches mostly females under 13 years of age. Besides, it is a complicated crime to prove, as 85.8% of female examinations and 96.2% of male exams revealed: “no supporting elements” or “undetermined” to characterize the felony. Therefore, to prevent it, the communication of the alleged rape must be made as quickly as possible.

Sperm hunting on optical microscope slides for forensic analysis with deep convolutional networks - a feasibility study

Microscopic sperm detection is an important task in sexual assault cases. In some instances, the samples contain no or only low amounts of semen. Therefore, the biological material is transferred onto a glass slide and needs to be manually scanned using an optical microscope. This work can be very time consuming, especially when no spermatozoa is present. In such a case, the result needs to be validated. In this article we show how convolutional neural networks can perform this task and how they can reduce the scanning time by locating the sperm cells on images taken under the microscope. For this purpose, we trained a VGG19 network and a VGG19 variation with 1942 images, some containing sperm cells and some not.

Prevalence and Recovery of Microorganisms from Containers used for the Collection of Forensic Biological Samples

Background:

Microbes play a significant role in the degradation of biological evidence collected for forensic analysis. The present study is aimed to isolate and identify the microbes present inside the empty container used for the biological evidence collection.

Methods:

Bacterial isolation from the selected containers was done by cotton swab over the inner surface of the containers. Streaking was done on the surface of the three different culture plates as a Blood agar plate, Nutrient plate and MacConkey plate. The plates were placed in an incubator shaker at 37ºC for 48 hours. The colonies grown on the surface of the media were counted on and used for further study. Various biochemical assays were performed to characterize isolated bacteria.

Results:

Staining results suggested that the presence of Gram-positive stain (Staphylococcus, Bacillus, Corynebacterium, Clostridium) and Gram negative stain (E. coli, Enterobacteriaceae, Pseudomonas, Salmonella, Shigella, Stenotrophomonas, Bdellovibrio, Acetic acid bacteria). The Catalase and Coagulase test suggested the presence of Staphylococcus aureus, S. epidermis and S. sapropyticus. Moreover, the indole test suggested the presence of Citrobacter koseri, Kebsiella oxytoca, Proteus vulgaris etc. Some of the bacteria were urea metabolizing, including Proteus spp, Helicobacter pylori, Cryptococcus spp, Corynebacterium spp.

Conclusion:

This study recommends that there should be proper maintenance of the chain of custody from the collection to analysis so that evidence properly prevents degradation or contamination in the biological evidence. Extra care is needed for the collection and packing of biological evidence from the crime scene. Moreover, the collection containers, if left wide open, lead to contamination and degradation of biological evidence.

PFSA DNA database: A tool to hunt the serial offenders

A forensic DNA database comprises of thousands of DNA profiles generated from suspects, convicts or even from common people from society. It is used for the cross-matching of DNA profiles obtained from evidence items collected from a crime scene. These databases are playing a core role in clearing the innocent and solving the dead-end unresolved crimes ultimately leading to crime reduction. In March, 2017, a nine years old minor girl was raped in district Khushab (Province Punjab). The medico-legal examiner indicated brutal sexual violence on the victim. Police apprehended a suspect who was excluded as the source of foreign male DNA from tested evidence items. Thus the case put up a question mark on the capabilities and efficiency of the police. An unknown male DNA profile obtained from evidence items was uploaded to PFSA DNA Database to maintain record. Later on, a suspect was arrested by Karachi (Province Sindh) police in another rape case, DNA profile of suspect was searched in the PFSA DNA Database. This generated DNA profile matched with the foreign DNA profile obtained from evidence items of minor victim, hence this atrocious crime was resolved. PFSA DNA Database provides support to criminal prosecution and also leads to identify potential suspects. It took years of effort to develop the rich PFSA DNA Database which subsequently proved to be fruitful in the exoneration of innocents and conviction of offenders in criminal cases.

Care of women and girls after sexual assault in Geneva: A descriptive study between 2005 and 2014

BACKGROUND AND PURPOSE

We aimed to examine epidemiological data and identify risk factors for sexual assault. This study included women seeking care at the Geneva University Hospitals emergency obstetrics and gynaecological unit.

METHOD

Retrospective, sociodemographic, and clinical data were collected from the medical reports.

RESULTS

We reviewed 836 medical charts and registered 92.8 women and girls per year who consulted the emergency department after sexual assault. The average age was 26 (±12) years, with a median of 23 years. Body lesions were reported in 525 patients (63%) and genital traumatic lesions were reported in 230 (28%) patients. Sexual assault by a stranger was reported in 436 cases (52%). Thirty percent of patients knew their aggressor. Aggressions were predominantly committed on the weekend, accounting for 367 cases (46%), with nearly two-thirds (65%, n = 474) occurring between 10 pm and 6 am. In total, 399 (48%) patients who were sexually assaulted reported having consumed alcohol and 102 (12%) reported having taken drugs prior to the aggression; 80 (10%) patients had consumed both and 286 (34%) had amnesia. Half of the sample sought and received medical care within 24 h from the time the aggression took place.

CONCLUSION

Sexual assault risk factors in our study population in Geneva included use of drugs and alcohol, with amnesia. Future prevention and education interventions should target these areas.

DNA evidence in sexual assault cases in Pakistan

Sexual assault is becoming a global epidemic, affecting close to a billion women throughout the world. This paper explores the challenges in the admissibility of DNA evidence in rape cases in Pakistan. Delays in the medical examination of victims, and improper collection and packaging of evidentiary material, compromise the probative biological evidence. In the last few years, existing laws have been amended to increase the utility of DNA evidence during criminal trials. However, various issues - for example lack of proper knowledge of DNA evidence by lawyers and judicial officers, inadequacies in existing laws and conflicting decisions of apex courts - can affect the admissibility of DNA evidence during criminal trials.

Challenges in Human Skin Microbial Profiling for Forensic Science: A Review

The human microbiome is comprised of the microbes that live on and within an individual, as well as immediately surrounding them. Microbial profiling may have forensic utility in the identification or association of individuals with criminal activities, using microbial signatures derived from a personal microbiome. This review highlights some important aspects of recent studies, many of which have revealed issues involving the effect of contamination of microbial samples from both technical and environmental sources and their impacts on microbiome research and the potential forensic applications of microbial profiling. It is imperative that these challenges be discussed and evaluated within a forensic context to better understand the future directions and potential applications of microbial profiling for human identification. It is necessary that the limitations identified be resolved prior to the adoption of microbial profiling, or, at a minimum, acknowledged by those applying this new approach.

Forensic Genetics and Genotyping

Forensic genetics represents a combination of molecular and population genetics. Personal identification and kinship analysis (e.g. paternity testing) are the two main subjects of forensic DNA analysis. Biological specimens from which DNA is isolated are blood, semen, saliva, tissues, bones, teeth, hairs. Genotyping has become a basis in the characterization of forensic biological evidence. It is performed using a variety of genetic markers, which are divided into two large groups: bi-allelic (single-nucleotide polymorphisms, SNP) and multi-allelic polymorphisms (variable number of tandem repeats, VNTR and short tandem repeats, STR). This review describes the purpose of genetic markers in forensic investigation and their limitations. The STR loci are currently the most informative genetic markers for identity testing, but in cases without a suspect SNP can predict offender’s ancestry and phenotype traits such as skin, eyes and hair color. Nowadays, many countries worldwide have established forensic DNA databases based on autosomal short tandem repeats and other markers. In order for DNA profile database to be useful at a national or international level, it is essential to standardize genetic markers used in laboratories.

Care of victims of suicide bombing

Summary

Suicide bombers often target crowds. This commentary discusses the additional features required in a medical response beyond conventional mass casualty care, including forensic documentation, preservation of evidence, suspect tissue identification and viral status, victim counselling and postexposure prophylaxis. We propose a pathway for care of victims of a suicide bomb, adapting elements from protocols for child abuse, sexual assault and needle-stick exposure.

Microbial Degradation of Forensic Samples of Biological Origin: Potential Threat to Human DNA Typing

Forensic biology is a sub-discipline of biological science with an amalgam of other branches of science used in the criminal justice system. Any nucleated cell/tissue harbouring DNA, either live or dead, can be used as forensic exhibits, a source of investigation through DNA typing. These biological materials of human origin are rich source of proteins, carbohydrates, lipids, trace elements as well as water and, thus, provide a virtuous milieu for the growth of microbes. The obstinate microbial growth augments the degradation process and is amplified with the passage of time and improper storage of the biological materials. Degradation of these biological materials carriages a huge challenge in the downstream processes of forensic DNA typing technique, such as short tandem repeats (STR) DNA typing. Microbial degradation yields improper or no PCR amplification, heterozygous peak imbalance, DNA contamination from non-human sources, degradation of DNA by microbial by-products, etc. Consequently, the most precise STR DNA typing technique is nullified and definite opinion can be hardly given with degraded forensic exhibits. Thus, suitable precautionary measures should be taken for proper storage and processing of the biological exhibits to minimize their decaying process by micro-organisms.

Contribution to the Development of Guidelines in the Analysis of Biological Evidence in Sexual Assault Investigations

This investigation intends to study materials and techniques used for biological evidence collection in sexual assault cases and is divided into two stages: in stage one, methods for biological evidence collection (the single swab (including three variants) and the "double swab technique") were compared; in stage two, swabs' component material was compared. The sampling was composed of 42 heterosexual couples who provided mock samples. The collection methods in which the whole swab is covered by evidence presented significantly better outcomes (p < 0.001), such as the "double swab technique." Additionally, nylon swabs proved to present significantly better features regarding the capacity of sample elution, providing significantly higher amounts of DNA (p ≤ 0.034). This study provides guidelines for better collection of biological evidence regarding the collection method using a swab and the proper swab material to utilize.

A Comparison Among Three Multiplex Y-STR Profiling Kits for Sexual Assault Cases

Biological evidence of sexual assault is one of the most difficult sample types to analyze in forensic laboratories. Y-STR markers are thus a valuable tool for analyzing these samples. The aim of this project was to compare three Y-STR commercial kits by analyzing their amplification performance on casework samples. Overall, 247 trace samples were analyzed with a Yfiler^® Plus PCR Amplification Kit (Applied Biosystems), PowerPlex^® Y23 (Promega^® ) System and AmpFLSTR^® Yfiler™ PCR Amplification Kit (Applied Biosystems). Comparing the amplification performance of the three kits, the first two were significantly more sensitive than the latter (p < 0.001). For samples, with a male DNA quantity less than 0.5 ng, the PowerPlex Y23^® kit was the most sensitive and best performing kit, followed by the Yfiler^® Plus kit (p = 0.009). In conclusion, the Yfiler^® Plus and PowerPlex Y-23^® kits are viable alternatives to older kits for samples with low amounts of male DNA.

A retrospective study of sexual offences in Zambia

Zambia has recently reported high incidences of sexual abuse against women and children. Zambian law categorises sexual offences into rape, defilement, incest and others, with defilement constituting the majority of the reported cases (>89%). Between 2010 and 2012, convictions of defilement cases were achieved in only 13% of cases reported to the police. DNA evidence has shown prominence in resolving crimes, specifically as an identification tool in sexual offences. Currently there is no empirical evidence describing the role of forensic evidence in sexual crimes in Zambia; as such a retrospective study was conducted to evaluate this between 2007 and 2014 (n = 1154). Only 14 (0.1%) of the cases had forensic samples collected in the form of a vaginal swab for semen analysis. In all cases where a suspect was identified (60%), identification was based on the witness/victim testimonies, and in no case, was forensic DNA evidence used to assist in identification or corroborate the testimonies. Overall, 28.1% of cases were taken to court and the conviction rate was 12.4%. These findings support the use of employing DNA evidence in sexual offence cases to aid the identification of suspects, which is hypothesised to increase the number of cases prosecuted in Zambia.