Forensic Spermatozoa Detection

Forensic parasitology: a new frontier in criminalistics

Parasites are ubiquitous, diverse, and have close interactions with humans and other animals. Despite this, they have not garnered significant interest from forensic scientists, and their utility as indicators in criminal investigations has been largely overlooked. To foster the development of forensic parasitology we explore the utility of parasites as forensic indicators in five broad areas: (i) wildlife trafficking and exploitation, (ii) biological attacks, (iii) sex crimes, (iv) criminal neglect of humans and other animals, and (v) indicators of movement and travel. To encourage the development and growth of forensic parasitology as a field, we lay out a four-step roadmap to increase the use and utility of parasites in criminal investigations.

Characterization of male sexual assault in the state of São Paulo, Brazil: an epidemiological study from 2014 to 2017

Sexual violence is a pervasive global issue that affects individuals of all genders. However, the experiences of male survivors have often been marginalized and inadequately represented. Male rape, which encompasses several forms of sexual violence against men, remains a sensitive and under-discussed topic in academic literature and public discourse. This study presents a descriptive cross-sectional analysis based on data collected from the Legal Medicine Institute (IML-São Paulo, Brazil) between 2014 and 2017. The analysis includes 7386 reports of sexological examinations performed on male victims of alleged rape. The analysis reveals that a significant majority of rape reports involved victims under the age of 12 or 14, which is considered vulnerable rape by the Brazilian legislation. Regarding the examination of reported cases of abuse against men, it was observed that only the minority of these cases exhibited visible injuries consistent with rape or tested positive for the presence of spermatozoa in the perianal region. Since the absence of visible injuries or spermatozoa does not negate the possibility of rape, this work highlights the challenges in obtaining conclusive evidence, necessitating a comprehensive approach to investigate and prosecute these crimes, creating a more inclusive and supportive environment for all survivors of rape, irrespective of their gender.

Evaluation of the effect of ozone disinfection on forensic identification of blood, saliva, and semen stains

Good laboratory practice minimizes the biological hazard posed by potentially infectious casework samples. In certain scenarios, when the casework sample is contaminated with highly contagious pathogens, additional safety procedures such as disinfection might be advised. It was previously proven that ozone gas treatment does not hamper STR analysis, but there is no data on how the disinfection affects other steps of the forensic analysis. In this study, we aimed to assess the interference of ozone disinfection with forensic tests used to identify biological stains. A dilution series of blood, saliva, and semen samples were pipetted onto cotton fabric and let completely dry. Half of the samples were subjected to ozone treatment, while the rest served as controls. All the samples were tested with specific lateral flow immunochromatographic assays and for specific RNA markers with quantitative real-time PCR. Additionally, luminol test was carried out on blood spots, Phadebas® Amylase Test on saliva stains, and semen stains were examined with STK Lab kit and light microscope following Christmas Tree or Hematoxylin-Eosin staining. Ozone treatment had no detrimental effect on the microscopic identification of sperm cells. Undiluted blood samples were detected with luminol and immunoassay, but at higher dilution, the sensitivity of the test decreased after disinfection. The same decrease in sensitivity was observed in the detection of semen stains using STK Lab kit from STK® Sperm Tracker, and in the case of the immunoassay specific for prostate-specific antigen (PSA). Ozone treatment almost completely inhibited the enzymatic activity of amylase. The sensitivity of antibody-based detection of amylase was also greatly reduced. RNA markers showed degradation but remained detectable in blood and semen samples after incubation in the presence of ozone. In saliva, the higher Ct values of the mRNA markers were close to the detection limit, even before ozone treatment.

Separation mixed semen of two individuals using magnetic beads coupled ABH blood group antibody

In sexual assault cases, one of the most common samples collected is a mixed semen stain, which is often found on the vagina, female underwear, or bed sheets. However, it is usually difficult to identify the perpetrator based on this sample alone. One technique that has been developed to address this issue is magnetic bead-based separation. This method involves using modified magnetic microspheres to capture and enrich specific target cells, in this case, sperm cells. In this study, we utilized magnetic beads coupled with ABH blood group antibody to isolate sperm cells from an individual of a single ABO blood type. Subsequently, polymerase chain reaction amplification and capillary electrophoresis were employed to perform the genotyping the short tandem repeat (STR) loci. This approach allows for the identification of different individuals in a mixed seminal stain sample from two individuals, by first separating sperm cells based on ABH antigen differences and subsequently utilizing autosomal STR typing on the enriched single blood group cells.

Study on Sperm-Cell Detection Using YOLOv5 Architecture with Labaled Dataset

Infertility has recently emerged as a severe medical problem. The essential elements in male infertility are sperm morphology, sperm motility, and sperm density. In order to analyze sperm motility, density, and morphology, laboratory experts do a semen analysis. However, it is simple to err when using a subjective interpretation based on laboratory observation. In this work, a computer-aided sperm count estimation approach is suggested to lessen the impact of experts in semen analysis. Object detection techniques concentrating on sperm motility estimate the number of active sperm in the semen. This study provides an overview of other techniques that we can compare. The Visem dataset from the Association for Computing Machinery was used to test the proposed strategy. We created a labelled dataset to prove that our network can detect sperms in images. The best not-super tuned result is mAP 72.15.

Typing of semen-containing mixtures using ARMS-based semen-specific CpG-InDel/STR markers

Mixed traces are common biological materials found at crime scenes, and their identification remains a significant challenge in the field of forensic genetics. In recent years, DNA methylation has been considered as a promising approach for body fluid identification, and length polymorphic loci are still the preferred markers for personal identification. In this study, we used tissue-specific CpG sites with linked insertion or deletion (InDel) or short tandem repeat (STR) markers (CpG-InDel/STR) for both body fluid and individual identification. The tissue-specific CpG loci, which were all selected from the previous reports, were analyzed using a combination of bisulfite conversion and amplification refractory mutation system-multiprimer-PCR technology. InDels or STRs, which were selected within 400 bp upstream or downstream of the semen-specific CpG loci, were analyzed using a capillary electrophoresis platform. Eventually, we successfully constructed a panel containing 17 semen-specific CpG-InDel/STR compound markers compassing 21 InDels/STRs, 3 body-fluid positive controls (vaginal secretion-, saliva-, and blood-specific CpG), and 1 gender identification locus. Using this panel, full genotyping of individuals could be obtained successfully with 50 ng DNA input. Semen stains stored at room temperature for 7 months and degraded samples that were heat treated for up to 6 h were still identified efficiently. For semen containing mixed stains, it is also useful when the semen content is as low as 3.03%. Moreover, the cumulative discrimination power of this panel is 0.9999998. In conclusion, it is a robust panel enabling the validation of both the tissue source and individual identification of semen containing mixed stains and can be employed as an alternative solution for forensic case investigation.

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.

Comparative Study of Acute Anogenital Injury Between Consensual and Nonconsensual Postmenarche Adolescents

ABSTRACT

In Thailand, sexual activity involving those under the legal age of consent may be legally and medically problematic, even if it is consensual. Thus, differentiating anogenital injury characteristics that occur during consensual versus nonconsensual acts with adolescent female subjects could aid legal advocates and improve health care and social support for these patients. Our study included postmenarche female patients having acute anogenital injuries after consensual and nonconsensual penetration. We found that nonconsenting patients had more cases of anogenital injury than consenting (69.8% vs 55.5%), with at least 1 abrasion, contusion, laceration, labia major or minor injury, and external or internal site injury. Both consensual and nonconsensual cases had the same common sites for injury type, reflecting the same injury mechanism; prior sexual intercourse was a significant protective factor against some anogenital injury prevalence, types, and sites for both groups. Adolescents forced into nonconsensual acts had more nonanogenital injuries. Looking at factors such as age, prior sexual activity history, and use of condom and/or contraceptive pills, it is very clear that early sexual education, particularly around consent, is critically needed in Thailand for the best interests of adolescents and children so that they and/or their guardians can access the health and legal resources required.

DNA Transfer in Forensic Science: Recent Progress towards Meeting Challenges

Understanding the factors that may impact the transfer, persistence, prevalence and recovery of DNA (DNA-TPPR), and the availability of data to assign probabilities to DNA quantities and profile types being obtained given particular scenarios and circumstances, is paramount when performing, and giving guidance on, evaluations of DNA findings given activity level propositions (activity level evaluations). In late 2018 and early 2019, three major reviews were published on aspects of DNA-TPPR, with each advocating the need for further research and other actions to support the conduct of DNA-related activity level evaluations. Here, we look at how challenges are being met, primarily by providing a synopsis of DNA-TPPR-related articles published since the conduct of these reviews and briefly exploring some of the actions taken by industry stakeholders towards addressing identified gaps. Much has been carried out in recent years, and efforts continue, to meet the challenges to continually improve the capacity of forensic experts to provide the guidance sought by the judiciary with respect to the transfer of DNA.

Generating aptamers towards human sperm cells using massively parallel sequencing

Determining the presence of sperm cells on an item or swab is often a crucial component of sexual offence investigation. However, traditional histological staining techniques used for the morphological identification of spermatozoa lack both specificity and sensitivity, making analysis a complex and time-consuming process. New methods for the detection of sperm cells based on aptamer recognition may be able to overcome these issues. In this work, we present the selection of ssDNA aptamers against human sperm cells using Cell-SELEX and massively parallel sequencing technologies. A total of 14 rounds of selection were performed following a modified Cell-SELEX protocol, which included additional steps for the isolation of spermatozoa from seminal fluid. Massively parallel sequencing using the Illumina Miseq platform was conducted on enriched aptamer pools to elucidate the structure of potential binders. A custom bioinformatics pipeline was also developed using Galaxy for the automated processing of sequencing datasets. This data revealed several promising aptamer candidates, which were shown to selectively bind sperm cells through both microscale thermophoresis and enzyme-linked oligonucleotide assays. These aptamers have the potential to increase the efficiency of sexual offence casework by facilitating sperm detection.