Refinement and validation of multi-source blood detection for operational use.
Authors:   , Kennedy Katie 
Published: November 2022

The operational deployment of any technique in forensic casework must undergo thorough investigation of its capabilities and limitations. At Sheffield Hallam University for the past 14 years, the Francese Group have focused on developing the utilisation of Matrix Assisted Laser Desorption Ionisation Mass Spectrometry (MALDI MS) for forensic applications. Not only has this technique shown potential in several different areas (MALDI MS analysis of latent fingermarks, condom lubricants and drug detection in fingermarks and hair as some examples), also being deployed in casework, but in more recent years, the detection of blood also. The end users, namely police and forensic providers have shaped the programme of work on blood detection by letting priorities and needs drive the research. The validation studies conducted in this thesis offer evidence of robustness and versatility as well as further insights as to what circumstances MALDI MS would be most suited/needed for the investigation of blood at a sceneof a violent crime. Currently, crime scene investigators (CSI) and crime labs employ commercially available presumptive tests for the detection of blood when recovered from crime scenes. However, these tests are not specific and occasionally yield false positives. Furthermore, confirmatory testing is not routinely performed. The risk of a false positive result could potentially result in a wrongful conviction or dismissal in court and brings into question the validity of these tests when their findings are heavily relied on in judicial proceedings. The utilisation of MALDI MS Profiling (MSP) and MS Imaging (MSI) for the rapid and informative detection of blood in this thesis has shed light on the multiplex nature of this alternative approach. A great deal of the work presented has shown the capability to not only distinguish between human and animal blood, but to determine blood provenance down to the species level (Chapter 2). In terms of animal blood detection, even more intelligence has been gained within this strand of the project, highlighting that a distinction can be made between intravenous animal blood and traces of animal blood from packaged meat (Chapter 4). If animal blood was detected at a crime scene, being able to offer insight on the manner in how the blood was shed could offer considerable assistance in reconstructing the dynamics of the crime. The compatibility and robustness testing performed in this project, which has been demonstrated across several strands of the project (Chapters 2,3 and 5) has additionally shown that MALDI MS can be used in conjunction with several blood enhancement techniques (BET), deposition surfaces, in the co-presence of other biofluids, and in tandem with DNA typing post MALDI MSI analysis. This body of knowledge significantly contributes to further advance implementation of MALDI based approaches for the forensic analysis of blood in stains and fingermarks in an operational environment and to the further promotion of MALDI as a Category A technique in the Home Office Fingermark Visualisation Manual after its recent promotion to Category B.