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.
Highlights
The reliable detection of bloodstains at the scene of violent crimes is of crucial importance to both reconstruct the dynamics of the crime and to provide, if present, associative evidence
Trifluoroacetic acid (TFA), α-cyano-4-hydroxycinnamic acid (α-CHCA) and Millipore ZipTips containing C18 stationary phase and TLC sheets were purchased from Sigma Aldrich (Poole, UK)
Sigma dry tubed swabs were sourced from Medical Wire (MWE) (Wiltshire, UK) and RapiGest was obtained in 1 mg vials from Waters (Wilmslow, UK)
Summary
The reliable detection of bloodstains at the scene of violent crimes is of crucial importance to both reconstruct the dynamics of the crime and to provide, if present, associative evidence. A less reported example is represented by the false positive reaction of acid dyes to biofluids other than blood, such as semen and saliva In this respect, the lack of specificity in the identification of blood is worsened by the risk of not detecting other types of biofluids which are important indicators of the crime being committed. Other important aspects to consider are sequential workflows to gather a body of intelligence from a single evidential source Blood tests such as the presumptive haem specific Luminol, BlueStar and confirmatory tests such as the Takayama Test, have been shown to result in DNA degradation at 30 days post application; this may be an issue for cases when further DNA analysis is required[3] but the analysis is not conducted immediately after collection. The need to acquire a reference spectrum at a crime scene without any blood would be challenging, as blood contaminated stains or fingermarks can often be latent at crime scenes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
