A Review of Spectroscopic Methods Applied to Bloodstain Pattern Analysis

Abstract

Blood is a common form of evidence found at a crime scene.  Bloodstain collection and analysis can provide useful information to the investigation, including but not limited to determining the identity of the blood source, and providing context to the events of bloodshed. Studies have attempted to use spectroscopy as a means of detecting, differentiating, and estimating the age of bloodstains.  In this review, current spectroscopic techniques Raman, Infrared (IR), Reflectance, Nuclear Magnetic Resonance (NMR), Electron Paramagnetic Resonance (EPR) spectroscopies and others are explained and discussed.  Recent advances are highlighted, and the respective advantages and limitations are examined.  Raman and IR spectroscopies, as well as hyperspectral imaging, hold the most promise for future use. These techniques are found to have higher sensitivities and accuracy rates than other traditional methods, as well as have the capability to be used in portable devices for on-site analysis. Reflectance spectroscopy could potentially be used as a presumptive test for the differentiation of bloodstains, but requires further validation.  NMR and EPR spectroscopic methods also performed with high accuracy and specificity, but require extensive expertise and laboratory work to be of practical use. Other absorbance and force spectroscopies were found to be unreliable because they can be easily influenced by environmental factors and contaminants.  These methods were deemed potentially useful only for presumptive examinations.Based on recent literature, we predict major growth areas for the research and development and implementation of portable Raman and IR technologies into the crime scene.