Pre-validation of a MALDI MS proteomics-based method for the reliable detection of blood and blood provenance

Abstract: The reliable identification of blood, as well as the determination of its origin (human or animal) is of great importance in a forensic investigation. Whilst presumptive tests are rapid and deployed in situ, their very nature requires confirmatory tests to be performed remotely. However, only serological tests can determine blood provenance. The present study improves on a previously devised Matrix Assisted Laser Desorption Ionisation Mass Spectrometry (MALDI MS)—proteomics based method for the reliable detection of blood by enabling the determination of blood provenance. The overall protocol was developed to be more specific than presumptive tests and faster/easier than the gold standard liquid chromatography (LC) MS/MS analysis. This is considered a pre-validation study that has investigated stains and fingermarks made in blood, other biofluids and substances that can elicit a false-positive response to colorimetric or presumptive tests, in a blind fashion. Stains and marks were either untreated or enhanced with a range of presumptive tests. Human and animal blood were correctly discriminated from other biofluids and non-biofluid related matrices; animal species determination was also possible within the system investigated. The procedure is compatible with the prior application of presumptive tests. The refined strategy resulting from iterative improvements through a trial and error study of 56 samples was applied to a final set of 13 blind samples. This final study yielded 12/13 correct identifications with the 13th sample being correctly identified as animal blood but with no species attribution. This body of work will contribute towards the validation of MALDI MS based methods and deployment in violent crimes involving bloodshed

MALDI imaging of blood and blood provenance in old fingermarks

Reliable confirmation of the presence of blood in stains and marks is crucial to reconstruct the dynamics of a violent crime. MALDI MS Profiling (MALDI MSP) and MALDI MS Imaging (MALDI MSI) have been shown to be suitable confirmatory tests to this effect [1-4]. However, additional and important information is based on the attribution of the source of blood (animal or human), as a few murder cases in the public domain demonstrate. The Fingermark Research Group at Sheffield Hallam University, recently published on the validation of a MALDI MSP method to detect and distinguish between human and animal blood (down to the animal species level) in enhanced blood marks and stains analyzed in a blind fashion [5] (Figure 1). Here we use a combination of bottom-up proteomics and MALDI MSI to visualize blood of bovine or human origin in 4-year-old fingermarks. These are unused marks originating from the batch of blind samples on which the Kennedy et al. publication [5] was based

The need for a research culture in the forensic sciences.

The methods, techniques, and reliability of the forensic sciences in general, and the pattern identification disciplines in particular, have faced significant scrutiny in recent years. Critics have attacked the scientific basis for the assumptions and claims made by forensic scientists both in and out of the courtroom. Defenders have emphasized courts\u27 longstanding acceptance of forensic science evidence, the relative dearth of known errors, and practitioners\u27 skill and experience. This Article reflects an effort made by a diverse group of participants in these debates, including law professors, academics from several disciplines, and practicing forensic scientists, to find and explore common ground. To what extent do the forensic sciences need to change in order to place themselves on an appropriately secure foundation in the twenty-first century? We all firmly agree that the traditional forensic sciences in general, and the pattern identification disciplines, such as fingerprint, firearm, toolmark, and *726 handwriting identification evidence in particular, do not currently possess--and absolutely must develop--a well-established scientific foundation. This can only be accomplished through the development of a research culture that permeates the entire field of forensic science. A research culture, we argue, must be grounded in the values of empiricism, transparency, and a commitment to an ongoing critical perspective. The forensic science disciplines need to substantially increase their commitment to evidence from empirical research as the basis for their conclusions. Sound research, rather than experience, training, and longstanding use, must become the central method by which assertions are justified. In this Article, we describe the underdeveloped research culture in the non-DNA forensic sciences, offer suggestions for how it might be improved, and explain why it matters