Untargeted Metabolomics Profiling for Determination of the Time since Deposition of Biofluids in a Forensic Context: A Proof-of-Concept for Urine, Saliva, and Semen in Addition to Blood

Abstract

In a criminal trial, the reconstruction of a crime is one of the fundamental steps of the prosecution process. Common questions, such as what happened, where and how it happened, and who made it happen, need to be solved. Biological evidence at crime scenes can be crucial in the determination of these fundamental questions. One of the more challenging riddles to solve is the when? A trace left at a crime scene can prove a person’s presence at the crime scene. Knowledge about when it was deposited there, the time since deposition (TsD), would allow linking the person in space and time to the site. This could fortify allegations against a suspect or discharge accusations if proven to be outside of the temporal boundaries where a suspected crime had occurred. Determining the TsD has yet to become routine forensic casework, despite recent research efforts, especially for blood traces. However, next to blood, other biological traces are also commonly encountered in crime scenes. We here present a study to profile the metabolomes of artificially aged dried body fluid spots of blood, semen, saliva, and urine over 4 weeks by liquid chromatography high-resolution mass spectrometry and data-dependent acquisition. All four body fluids (BFs) exhibited diverse time-dependent changes, and a large number of molecular features (MF) were associated with TsD. Still, significant differences between the BFs were observed, limiting universal interpretability independent of the BF and facilitating a need to further study time-dependent changes of different BFs individually toward the goal of TsD estimation.

Targeted and untargeted metabolomics and lipidomics in dried blood microsampling: Recent applications and perspectives

“…However, the authors still concluded that using VAMS with capillary blood samples can capture biological differences of interest not found in plasma samples. 12 Conversely, Schneider et al 94 compared the use of DBSs with other body fluids and dried spots usually found in crime scenes aiming to find a universal biomarker and determine time since deposition.…”

“…From the blood-specific compounds, they verified that four of them (L-phenylalanyl-L-alanine, 3-indole acrylic acid, spermidine and argininosuccinic acid) could be used to monitor time since deposition dynamics over 4 weeks. 94 Two studies used untargeted metabolomics on DBSs to discover potential biomarkers for metabolic diseases associated with fatty acid β-oxidation: very VLCADD and MCADD. 95,96 The authors compared DBS samples from newborns positively diagnosed with the specific disorder against healthy controls.…”

“…Conversely, Schneider et al. 94 compared the use of DBSs with other body fluids and dried spots usually found in crime scenes aiming to find a universal biomarker and determine time since deposition. They peak‐picked 24,904 possible molecular features shared across all four body fluids.…”

“…From the blood‐specific compounds, they verified that four of them ( l ‐phenylalanyl‐ l ‐alanine, 3‐indole acrylic acid, spermidine and argininosuccinic acid) could be used to monitor time since deposition dynamics over 4 weeks. 94 …”