Fighting crime with mass spectrometry technology

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Fighting crime with mass spectrometry technology

Fingerprints have been the most powerful means of biometric identification for over a century. However, the process has remained largely unchanged in scope as only the physical characteristics of the ridge pattern are exploited to compare a crime scene mark with a fingerprint record. This process leads to suspect identification if a match is found. Nonetheless, current fingerprinting may fail as in the case of smudged, partial and/or overlapped marks, or no fingerprint record. 

A new technique

In 2008, the Fingerprint Research Group (FRG) at Sheffield Hallam University led by Professor Simona Francese, initiated the development of Matrix Assisted Laser Desorption Ionisation Mass Spectrometry Profiling/Imaging (MALDI MSP/I) based methods for the chemical profiling/imaging of fingermarks (molecular fingerprinting), as well as their translation in an operational environment. 

Molecular fingerprinting enhances the forensic value of the fingermark evidence by detecting and visualising the molecules that can be found within, including contaminants, naturally occurring and introduced into the body. These advancements enable a novel way to conduct criminal profiling to inform crime scene management, narrow down the pool of suspects and speed up investigations. 

The ridge pattern can be reconstructed through visualising detected molecules while keeping the fingerprint intact. The technology can provide ridge detail additional to that obtained by conventional CSI techniques in high spatial resolution (Figure 1).

A mass spectrometry image of a fingermark
Figure 1: MALDI MSI of a latent mark area acquired on a MRT MALDI qTOF mass spectrometer (Waters Corp. Manchester) at 20 µm spatial resolution (image provided by PhD student Katie Kennedy).

Identifying a suspect

Higher likelihood of suspect identification can be achieved through:

  • Stitching/superimposition of multiple molecular images from the thousands of molecules simultaneously detected (improving ridge pattern coverage/continuity).
  • Separating overlapping fingermarks by individually recalling images of molecules that are uniquely distributed in each overlapping mark (Figure 2). 
A mass spectrometry image of fingermarks
Figure 2: Separation of overlapping fingermarks by MALDI MSI. A: optical image of overlapping marks. B: Overlapping MALDI MS images from m/z signals unique to each mark. C: Separate recalling of MALDI MS images showing six different fingermarks (Bradshaw R. and Francese S, MALDI-MSI in the Forensic arena; In: Porta-Siegel T. (Ed) MALDI Mass Spectrometry Imaging: From Fundamentals to spatial Omics, RSC 2021).

The FRG pursued the recovery of personal and lifestyle information around the fingermark's owner and/or on their actions prior to or during committing the crime, enabling:

  • Determination of the sex of the suspect from their fingermark peptidic/protein composition.
  • Recovery of intelligence on the use of condoms, enabling associative/probative evidence in the context of crimes of sexual nature.
  • Detection and mapping of drugs. 
  • Specific and multi-informative detection of blood in marks/stains, compatible with CSI techniques.

Shaping the future of forensics

Since 2011, the applicability of molecular fingerprinting to crime scene investigation has attracted funding and research-shaping input from the Home Office, the Defence Science and Technology Laboratory (Dstl), West Yorkshire Police and the Netherlands Forensic Institute. 

As a result, molecular fingerprinting has been used in operational casework in the UK and overseas as well as being incorporated into the Dstl Fingermark Visualisation Manual, due to its high technology readiness level (TRL).

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Contact SMIC to discuss facilities and partnerships.

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