Current Methods for Body Fluid Identification Related to Sexual Crime: Focusing on Saliva, Semen, and Vaginal Fluid.

Koichi Sakurada,Ken Watanabe,Tomoko Akutsu

doi:10.3390/diagnostics10090693

Abstract

Although, DNA typing plays a decisive role in the identification of persons from blood and body fluid stains in criminal investigations, clarifying the origin of extracted DNA has also been considered an essential task in proving a criminal act. This review introduces the importance of developing precise methods for body fluid identification. Body fluid identification has long relied on enzymatic methods as a presumptive assay and histological or serological methods as a confirmatory assay. However, because the latest DNA typing methods can rapidly obtain results from very small and even old, poorly preserved samples, the development of a novel corresponding body fluid identification method is required. In particular, an immunochromatographic method has been introduced to identify saliva and semen from sexual crimes. In addition, for vaginal fluid identification, attempts have been made in the past decade to introduce a method relying on body fluid-specific mRNA expression levels. At present, the development of molecular biological methods involving microRNA, DNA methylation, and resident bacterial DNA is ongoing. Therefore, in criminal investigations, body fluid identification is an essential task for correctly applying the results of DNA typing, although further research and development are required.

Highlights

DNA analysis is used in most countries around the world to obtain individual genetic profiles and identify persons from biological samples linked to crimes for use in criminal investigations
Fujii et al [2] reported that the probability of identity of these 21 autosomal loci obtained using GlobalFiler was 1.84 × 10−25 in Japanese population, which was remarkably higher than that (1.8 × 10−17 ) of the 15 autosomal loci obtained using AmpFLSTR
Clarification of whether the sample concerns menstrual blood [13,14,15,16,17], maternal blood [18,19,20], fetal blood [21,22], or postmortem blood [15,23] is often required, and this identification is performed through assays that target proteins or expressed genes that are characteristic of each blood type

Summary

Introduction

DNA analysis is used in most countries around the world to obtain individual genetic profiles and identify persons from biological samples linked to crimes for use in criminal investigations. We can safely say that the body is composed of a huge number of cells. As all of these cells have the same DNA, when body fluid is the residual crime-related sample used, the DNA origin is essential in proving the criminal act. In sexual crimes, the identification of saliva, semen, and vaginal fluid is often required, and biochemical, histological, or instrumental analysis methods that focus on the characteristic proteins and cells in each type of body fluid have long been used. We review the current methods for identifying body fluids related to sexual crime, and we discuss both conventional methods and the latest serological and molecular biological methods, focusing on saliva, semen, and vaginal fluid

Flow of Forensic Examinations Using Biological Samples

Saliva Identification

Semen Identification

Vaginal Fluid Identification

Discussion