Identification and Determination of the Bloodstains Dry Time in the Crime Scenes Using Laser-Induced Breakdown Spectroscopy

Abstract

The bloodstain is one kind of the most important evidences in crime scenes. Laser-induced breakdown spectroscopy (LIBS) technology was used in this paper to distinguish bloodstains from analogs and determine the time since deposited (TSD) of bloodstains. Combined with support vector machine classifier, the identification results of bloodstains from analogs achieved 96% in 20 s. Four kinds of substrates were chosen to simulate the grounds and lethal tools in crime scenes. The linear relationship between single spectral line intensity and TSD was analyzed. The Pearson linear correlation coefficient (Pearson's r) calculated on the stone bricks calibration result is higher than 0.9. The spectral line intensity ratio was proposed to improve the linear calibration relationship with TSD. Building the calibration relationship between intensity ratios and TSDs, the Pearson's r and R 2 values for results on all four substrates were improved. For stone bricks, ceramic tiles, and copper plates, the correlation coefficients were all higher than 0.95. Especially for results on stone bricks, the Pearson's r achieved 0.99024 and the R 2 value achieved 0.97571. The optimal single lines for calibration on four substrates were all related to Fe element and the optimal line intensity ratios were all ratios of an Fe line to a line of other elements.

Laser-induced breakdown spectroscopy with neural network approach for plastic identification and classification in waste management

“…The simple procedure is highly efficient and minimally invasive. LIBS has been widely used in the metallurgy industry, Raw Materials Quality Monitoring [7] , Crime Scene investigation [8] , Investigation of electrical, thermal, and mechanical properties of nanocomposites [9] , Investigation of Surface Condition [10] , Medical applications [11,12] , Classification of Aged Epoxy Micro-Nanocomposites [13] and other environmental monitoring applications [14] .…”

The crux of time: A meta-analysis of ex vivo whole blood degradation

“…The rate of biomolecule degradation in bloodstains is partially dictated by substrate porosity; for example, hemoglobin oxidation is a faster process in dried states than in liquid states (Marrone and Ballantyne, 2009). Substrates range from common materials like glass, plastic and textiles to less common materials like soil (Hassan et al, 2019), wallpaper (Shin et al, 2017), leather (Kohlmeier and Schneider, 2012) and brick stones (Wang et al, 2019). The same applies to environmental conditions; warmer environments catalyze biomolecular degradation while colder environments preserve the biomolecules in their native states, slowing the degradation (Zadora and Menzyk, 2018).…”

The crux of time: A meta-analysis of ex vivo whole blood degradation

“…The type of substrate on which the bloodstain is deposited also influences TSD estimates 1 . Substrates range from common materials like glass, plastic and textiles to less common materials like soil 31 , wallpaper 14 , leather 67 and brick stones 87 . The same applies to environmental conditions; warmer environments catalyze biomolecular degradation while colder environments preserve the biomolecules in their native states, slowing the degradation 1 .…”