Separation of overlapping fingermarks by Matrix Assisted Laser Desorption Ionisation Mass Spectrometry Imaging

Desorption Electrospray Ionization Mass Spectrometry Imaging of Powder-Treated Fingermarks on Forensic Gelatin Lifters and its Application for Separating Overlapping Fingermarks

Fingermarks are frequently collected at crime scenes by using gelatin lifters for preservation and transport of the marks to a forensic laboratory for inspection. The gelatin lifters preserve both the imprint of the fingermark pattern necessary for identification purposes and the chemical residue of the mark potentially useful for profiling the person who left the fingermark. The fingermark patterns are traditionally recorded using photography/optical imaging, but methods for chemical analysis of fingermark residues on gelatin lifters are scarce. Here we report the first method for the chemical analysis of fingermarks on gelatin lifters using desorption electrospray ionization mass spectrometry (DESI-MS) imaging. The imaging can be done directly on the gelatin support without any sample preparation, supporting immediate operational use of the method for fingermarks collected at crime scenes. Operational use of the method is further supported by successful chemical imaging of fingermarks enhanced by traditional dusting with forensic powders and lifted off different surfaces (glass, stainless steel, painted aluminum, polystyrene, cardboard, and plastic) as well as fingermarks lifted multiple times. We also demonstrate that the present method can be used to visually separate natural overlapping powder-treated fingermarks, and the chemical composition of the fingermarks can be analyzed on the gelatin support by DESI-MS/MS. The presented method has potential for integration into the traditional workflow for fingermark analysis, and will allow more fingermarks collected at crime scenes to be evaluated both visually and chemically.

Forensic aspects of condom evidence: Analysis, interpretation, and recent trends

In recent years, collection and analysis of condom evidence in sexual assault investigations are becoming more common in forensic caseworks. Condom analysis can provide investigative leads or establish potential contact between the suspect and victim in the absence of DNA evidence or supplement biological evidence. Recent forensic literature shows significant advancements in the analysis of condom lubricants, including casework samples. There is an increasing trend in the use of chemometric tools for the comparison and interpretation of the results. This review highlights the advances in common analytical techniques used for the analysis of condom lubricants with a particular focus on the developments occurring in recent years, including chemometric interpretation. The analysis of reference and casework samples (swab samples, samples on skin, clothing and fingermark) are discussed separately. For casework samples, the transfer and persistence of different lubricant formulations are discussed, along with their detection with various analytical approaches. The issues with the interpretation of lubricants are also discussed in another section, with particular emphasis on samples such as personal hygiene products which have similar formulations with sexual lubricants and the interpretation of negative profiles. The current challenges in the field and prospects for future research are also discussed.

Rapid desorption and analysis for illicit drugs and chemical profiling of fingerprints by SICRIT ion source

Forensic analysis can encompass a wide variety of analytes from biological samples including DNA, blood, serum, and fingerprints to synthetic samples like drugs and explosives. In order to analyze this variety, there are various sample preparation techniques, which can be time-consuming and require multiple analytical instruments. With recent advancements in ambient ionization mass spectrometry (MS), plasma-based dielectric barrier discharge ionization (DBDI) sources have demonstrated to cover a wide range of these analytes. The flow-through design of this source also allows for easy connection to a thermal desorption type of sample introduction. We present an in-house built thermal desorption device where the sample is introduced via a glass slide, which gets heated and transferred to the DBDI-MS with nitrogen for identification and semi-quantification. Using a glass slide as an inexpensive sampling device, detection limits as low as 20 pg for fentanyl are demonstrated. Additionally, a very precise (>96% accuracy) identification of persons based on the chemical profile of their fingerprints is possible, establishing a direct analytical link of the drug trace to the individual in one measurement. We compared the DAG, TAG, sterol, and (semi-)volatile region of the averaged fingerprint spectra over multiple days, showing the best model accuracy for identification based on the DAG region. The combination of thermal desorption and DBDI-MS minimized sample preparation, leading to an ultrasensitive and rapid analysis of illicit drug traces and the identification of underlying personas based on fingerprints.

MALDI MSI Separation of Same Donor's Fingermarks Based on Time of Deposition-A Proof-of-Concept Study

Despite the advent of DNA profiling, fingerprints still play an important role in suspect identification. However, if single crime scene marks may be challenging to identify, overlapping fingermarks, understandably, pose an even greater challenge. In the last decade, mass spectrometry-imaging methods have provided a possible solution to the separation of fingermarks from two or more donors, based on the differential chemical composition. However, there are no studies attempting to separate overlapping marks from the same donor. This is important in relation to fingermark deposition at different times, which could be critical, for example, to ascertain legitimate access to the scene. In the work presented here, we investigate whether Matrix-Assisted Laser Desorption Ionisation Mass Spectrometry Imaging can separate the same donor's fingermarks deposited at different times based on intra-donor fingermark composition variability. Additionally, the hypothesis that the different times of deposition could be also determined was investigated in the view of linking the suspect at the scene at different times; the dating window of MALDI MSI within the selected molecular range was explored. Results show that it is possible to separate overlapping fingermarks from the same donor in most cases, even from natural marks. Fresh marks (0 days) could be separated from those of fourteen days of age, though the latter could not be distinguished from the set aged for seven days. Due to the use of only one donor, these are to be considered preliminary data, though findings are interesting enough to warrant further investigation of the capabilities and limitations of this approach using a larger cohort of donors.

Differentiating individuals through the chemical composition of their fingermarks

Fingermark patterns are one of the oldest means of biometric identification. During this last decade, the molecules that constitute the fingermark residue have gained interest among the forensic research community to gain additional intelligence regarding its donor profile including its gender, age, lifestyle or even its pathological state. In this work, the molecular composition of fingermarks have been studied to monitor the variability between donors and to explore its capacity to differentiate individuals using supervised multi-class classification models. Over one year, fingermarks from thirteen donors have been analysed by Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (n = 716) and mined by different machine learning approaches. We demonstrate the potential of the fingermark chemical composition to help differentiating individuals with an accuracy between 80% and 96% depending on the period of sample collection for each donor and size of the pool of donors. It would be premature at this stage to transpose the results of this research to real cases, however the conclusions of this study can provide a better understanding of the variations of the chemical composition of the fingermark residue in between individuals over long periods and help clarifying the notion of donorship.

Chemical composition of the fingermark residue: Assessment of the intravariability over one year using MALDI-MSI

These past years, the chemical composition of fingermarks have attracted interest of researchers to meet multiple objectives like the determination of an individual's age, gender or lifestyle or the impact of some fingermark detection processes, to cite a few. These studies have highlighted the need to investigate the consistency of the fingermark composition over time. This research explores the evolution of the secretion residue composition of thirteen donors over one year, focusing on the intravariability. The dual use of Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (MALDI-MSI) and chemometrics provided valuable data regarding the evolution of composition over time as well as the consistency of presence of hundreds of compounds.

Towards the protection of ammunition headstamps during fingermark enhancement processing; a preliminary study

Forensic recovery from fired ammunition casings remains one of the most challenging tasks during high-profile investigations. Often, the decision must be made between screening for DNA or fingerprints, and, in doing so, the impact these processes will have on the examination of ballistic markings imparted on the ammunition from the firearm itself. Traditionally, fingermark enhancement processes have yielded low success rates in their efforts to identify suspects by enhancing friction ridge detail left on the cartridge casings. Moreover, the enhancement methods utilised may often induce detrimental physical changes to the casing(s), rendering them unsuitable for subsequent ballistics (marking) examination. Recently, new technology has been shown to increase the success rate of fingermark recovery from fired ammunition, and the growing adoption of such innovation means that new challenges are encountered to maximise evidence recovery and streamline forensic workflows. One such example arises from the potential obscuration of the ammunition headstamp area during such treatments. Accordingly, this study outlines the preliminary investigations and developments of a polymer mask substrate that serves to protect the headstamp of fired ammunition casings during relevant fingermark enhancement processes. The technique also has the capacity to be used as a surface protection device to eliminate unwanted chemical deposition across other areas of interest and evidence types.

Recent Advances in Noninvasive Biosensors for Forensics, Biometrics, and Cybersecurity

Recently, biosensors have been used in an increasing number of different fields and disciplines due to their wide applicability, reproducibility, and selectivity. Three large disciplines in which this has become relevant has been the forensic, biometric, and cybersecurity fields. The call for novel noninvasive biosensors for these three applications has been a focus of research in these fields. Recent advances in these three areas has relied on the use of biosensors based on primarily colorimetric assays based on bioaffinity interactions utilizing enzymatic assays. In forensics, the use of different bodily fluids for metabolite analysis provides an alternative to the use of DNA to avoid the backlog that is currently the main issue with DNA analysis by providing worthwhile information about the originator. In biometrics, the use of sweat-based systems for user authentication has been developed as a proof-of-concept design utilizing the levels of different metabolites found in sweat. Lastly, biosensor assays have been developed as a proof-of-concept for combination with cybersecurity, primarily cryptography, for the encryption and protection of data and messages.

Methodologies Applied to Fingerprint Analysis

This systematic review deals with the last 10 years of research in analytical methodologies for the analysis of fingerprints, regarding their chemical and biological constituents. A total of 123 manuscripts, which fit the search criteria defined using the descriptor "latent fingermarks analysis," were selected. Its main instrumental areas (mass spectrometry, spectroscopy, and innovative methods) were analyzed and summarized in a specific table, highlighting its main analytical parameters. The results show that most studies in this field use mass spectrometry to identify the constituents of fingerprints, both to determine the chemical profile and for aging. There is also a marked use of mass spectrometry coupled with chromatographic methods, and it provides accurate results for a fatty acid profile. Additional significant results are achieved by spectroscopic methods, mainly Raman and infrared. It is noteworthy that spectroscopic methods using microscopy assist in the accuracy of the analyzed region of the fingerprint, contributing to more robust results. There was also a significant increase in studies using methods focused on finding new developers or identifying components present in fingerprints by rapid tests. This systematic review of analytical techniques applied to the detection of fingerprints explores different approaches to contribute to future studies in forensic identification, verifying new demands in the forensic sciences and assisting in the selection of studies for the progress of research.

Recent advances in the chemical imaging of human fingermarks (a review)

This review highlights the considerable advances in the chemical imaging of human fingermarks that provide more chemical information, including numerous endogenous and exogenous constituents. Despite remarkable development in DNA analysis and recognition, human fingermark analysis remains one of the priority approaches available for obtaining reliable forensic evidence. Additional information about the donor can be obtained from the chemical composition of latent fingermarks in addition to the ridge pattern, such as the age, gender, medical history, and possible drug habits. The analytical approaches reviewed here include spectroscopy, mass spectrometry, immuno-labelling and electrochemical methods. Each method has different capabilities with respect to sensitivity, reproducibility, selectivity, reliability and ultimately applicability, either for use in routine forensic practice or in academic research work. The advantages of spectroscopic techniques, including infrared, Raman and micro-X-ray fluorescence spectroscopy, are the capabilities of a rapid and non-destructive imaging of fingermarks by providing spectral information on chemical composition. In addition, mass spectrometry imaging can provide spatially specific information on fingermark chemical composition. Recently, the use of immuno-labelling in latent fingermark detection has attracted significant attention because it can overcome the sensitivity and selectivity problems experienced with other existing methods. The electrochemical method has also been employed to image latent fingermarks by measuring the electric current changes with the spatial chemical composition from the ridges and valleys at high resolution to provide a third level of detail, which is especially useful for multicoloured background surfaces or for surfaces contaminated with blood or other bodily fluids.

Forensic Discrimination of Latent Fingerprints Using Laser-Induced Breakdown Spectroscopy (LIBS) and Chemometric Approaches

A novel technique is reported for separating overlapping latent fingerprints using chemometric approaches that combine laser-induced breakdown spectroscopy (LIBS) and multivariate analysis. The LIBS technique provides the capability of real time analysis and high frequency scanning as well as the data regarding the chemical composition of overlapping latent fingerprints. These spectra offer valuable information for the classification and reconstruction of overlapping latent fingerprints by implementing appropriate statistical multivariate analysis. The current study employs principal component analysis and partial least square methods for the classification of latent fingerprints from the LIBS spectra. This technique was successfully demonstrated through a classification study of four distinct latent fingerprints using classification methods such as soft independent modeling of class analogy (SIMCA) and partial least squares discriminant analysis (PLS-DA). The novel method yielded an accuracy of more than 85% and was proven to be sufficiently robust. Furthermore, through laser scanning analysis at a spatial interval of 125 µm, the overlapping fingerprints were reconstructed as separate two-dimensional forms.

Application of mesocellular siliceous foams (MCF) for surface-assisted laser desorption ionization mass spectrometry (SALDI-MS) Analysis of fingermarks

Recent advances in nanotechnology applied in forensic sciences have contributed to consider new approaches including chemical evaluation of latent fingermarks. Significant improvement to the detection of small organic molecules has been reached with matrix-free methods associated to laser desorption/ionization mass spectrometry. The present study investigated the application of mesocellular siliceous foam (MCF) as an ionizing agent for laser desorption/ionization (LDI-MS) analysis of fingermarks as a proof of concept research. Fingermarks from three different donors were deposited directly onto a MALDI target plate and α-CHCA matrix solution, MCF ethanolic suspension or MCF/magnetic powder mixture were used for treatment. Microscopy characterization of MCF support showed particles with irregular morphology and variable sizes, and a unordered porous surface with pores diameter ranging from about 10 to 20 nm. Results showed less intense peaks in the spectra produced by the MCF support (control). Analysis of fingermarks showed ions related to endogenous and exogenous molecular components, including possible lipids from human sebum and quaternary ammonium cations commonly present in cosmetics. Promising and reproducible results were obtained for the fingermarks dusted with the MCF/magnetic powder mixture. Considering the forensic applications of nanomaterials for the analysis of small molecules in biological samples by matrix-free LDI techniques, the advantages of silica based materials should be further investigated.

Forensic analysis of latent fingermarks by silver-assisted LDI imaging MS on nonconductive surfaces

Silver-assisted laser desorption ionization (AgLDI) imaging mass spectrometry (IMS) has been demonstrated to be a useful technology for fingermark analysis allowing for the detection of several classes of endogenous as well as exogenous compounds. Ideally, in IMS analyses, the fingermarks are deposited under controlled conditions on metallized conductive target slides. However, in forensic investigations, fingermarks are often found on a variety of nonconductive surfaces. A sputtered silver layer renders the target surface conductive, which allows the analyses of insulating surfaces by time-of-flight IMS. Ultimately, the major consideration when developing analytical methods for the analysis of latent fingermarks is their capability to be incorporated within forensic standard operational procedures. To demonstrate the potential of AgLDI IMS for forensic applications, fingermarks deposited on nonconductive surfaces commonly found during an investigation, including paper, cardboard, plastic bags and lifting tape, were first revealed by the Sûreté du Québec by using forensic enhancement techniques prior to the IMS analyses. Numerous endogenous compounds including fatty acids, cholesterol, squalene, wax esters, triglycerides and several exogenous substances were detected and imaged. Here, we show that silver sputtering can provide visual enhancements of fingerprint patterns after FET procedures through different scenarios in which AgLDI IMS can contribute to forensic investigations. Copyright © 2017 John Wiley & Sons, Ltd.

MALDI Mass Spectrometry Profiling and Imaging Applied to the Analysis of Latent Fingermarks

Latent fingermarks are derived from a transfer of material from the fingertips to a surface upon contact. Traditionally, fingermarks are employed for biometric identification of individuals based on matching of the pattern of the ridges. However, in recent years, there has been a stark increase in the use of advanced analytical techniques in order to obtain additional information, specifically the chemical composition of the residue. Understanding the complexity of the endogenous and exogenous content of fingermarks could be extremely useful in allowing further development of enhancement techniques currently used in forensic scenarios by identifying potential target molecules. This chemical information could also potentially provide invaluable information on the lifestyle of an individual, including their activities prior to depositing a mark.An analytical tool that has gained notable popularity in this novel area of research is matrix-assisted laser desorption/ionisation mass spectrometry (MALDI MS). This technique can either be employed for rapid chemical profiling or imaging of fingermarks to detect chemical species contained within the residue, with the latter also allowing for physical reconstruction of the fingermark ridges.This chapter will provide an overview of the protocols employed to allow for both MALDI MS profiling and imaging analysis of latent fingermarks, specifically covering the types of fingermarks employed and techniques used to deposit matrices onto samples.

An update on MALDI mass spectrometry based technology for the analysis of fingermarks – stepping into operational deployment

Expanded range of retrievable intelligence from fingermarksviaMALDI MS based methods and increased operational capabilities of the technology.

Implementation of MALDI MS profiling and imaging methods for the analysis of real crime scene fingermarks

First insights into MALDI MS based method's transition to operational casework involving fingermark analysis.

Imaging mass spectrometry of elements in forensic cases by LA-ICP-MS

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was performed to map elements in thin formalin-fixed paraffin-embedded tissue sections of two forensic cases with firearm and electrocution injuries, respectively. In both cases, histological examination of the wounded tissue regions revealed the presence of exogenous aggregates that may be interpreted as metallic depositions. The use of imaging LA-ICP-MS allowed us to unambiguously determine the elemental composition of the observed aggregates assisting the pathologist in case assessments. To the best of our knowledge, we demonstrate for the first time the use of imaging LA-ICP-MS as a complementary tool for forensic pathologists and toxicologists in order to map the presence of metals and other elements in thin tissue sections of post-mortem cases.

The Reed-Stanton press rig for the generation of reproducible fingermarks: Towards a standardised methodology for fingermark research

In the search for better or new methods/techniques to visualise fingermarks or to analyse them exploiting their chemical content, fingermarks inter-variability may hinder the assessment of the method effectiveness. Variability is due to changes in the chemical composition of the fingermarks between different donors and within the same donor, as well as to differential contact time, pressure and angle. When validating a method or comparing it with existing ones, it is not always possible to account for this type of variability. One way to compensate for these issues is to employ, in the early stages of the method development, a device generating reproducible fingermarks. Here the authors present their take on such device, as well as quantitatively describing its performance and benefits against the manual production of marks. Finally a short application is illustrated for the use of this device, at the method developmental stages, in an emerging area of fingerprinting research concerning the retrieval of chemical intelligence from fingermarks.

Detection and mapping of illicit drugs and their metabolites in fingermarks by MALDI MS and compatibility with forensic techniques

Despite the proven capabilities of Matrix Assisted Laser Desorption Ionisation Mass Spectrometry (MALDI MS) in laboratory settings, research is still needed to integrate this technique into current forensic fingerprinting practice. Optimised protocols enabling the compatible application of MALDI to developed fingermarks will allow additional intelligence to be gathered around a suspect’s lifestyle and activities prior to the deposition of their fingermarks while committing a crime. The detection and mapping of illicit drugs and metabolites in latent fingermarks would provide intelligence that is beneficial for both police investigations and court cases. This study investigated MALDI MS detection and mapping capabilities for a large range of drugs of abuse and their metabolites in fingermarks; the detection and mapping of a mixture of these drugs in marks, with and without prior development with cyanoacrylate fuming or Vacuum Metal Deposition, was also examined. Our findings indicate the versatility of MALDI technology and its ability to retrieve chemical intelligence either by detecting the compounds investigated or by using their ion signals to reconstruct 2D maps of fingermark ridge details.

Analysis of sexual assault evidence: statistical classification of condoms by ambient mass spectrometry

Desorption electrospray ionization mass spectrometry (DESI-MS) and easy ambient sonic-spray ionization mass spectrometry (EASI-MS) are employed here in the forensic analysis of chemical compounds found in condoms and relative traces, and their analytical performances are compared. Statistical analysis of data obtained from mass spectra only was applied in order to obtain classification rules for distinguishing ten types of condoms. In particular, two supervised chemometric techniques [linear discriminant analysis (LDA) and soft independent modeling of class analogy (SIMCA)] were carried out on absolute and relative intensity values to test the performances of statistical models in terms of predictive capacity. The achieved classification of samples was excellent because of the high prediction percentages of the method used both for DESI and EASI mass spectrometry analyses, confirming these two as potential ambient ionization techniques for forensic analyses in case of sexual assault crimes. EASI-MS showed 99% prediction ability for LDA using relative data and 100% prediction ability for SIMCA using both absolute and relative ones, while DESI showed 94% prediction ability for both LDA and SIMCA. The absence of any sample preparation technique gives advantages in terms of sample preservation and reduced contamination, allowing successive analyses to be performed on the same sample by other techniques.

Ultrafast high-resolution mass spectrometric finger pore imaging in latent finger prints

Latent finger prints (LFPs) are deposits of sweat components in ridge and groove patterns, left after human fingers contact with a surface. Being important targets in biometry and forensic investigations they contain more information than topological patterns. With laser desorption mass spectrometry imaging (LD-MSI) we record ‘three-dimensional' finger prints with additional chemical information as the third dimension. Here we show the potential of fast finger pore imaging (FPI) in latent finger prints employing LD-MSI without a classical matrix in a high- spatial resolution mode. Thin films of gold rapidly sputtered on top of the sample are used for desorption. FPI employing an optical image for rapid spatial orientation and guiding of the desorption laser enables the rapid analysis of individual finger pores, and the chemical composition of their excretions. With this approach we rapidly detect metabolites, drugs, and characteristic excretions from the inside of the human organism by a minimally-invasive strategy, and distinguish them from chemicals in contact with fingers without any labeling. The fast finger pore imaging, analysis, and screening approach opens the door for a vast number of novel applications in such different fields as forensics, doping and medication control, therapy, as well as rapid profiling of individuals.

Surface modification for the collection and identification of fingerprints and colorimetric detection of urea nitrate

Glass surfaces were modified with a combination of dyes and reagents to allow for the potential simultaneous recording of a detailed fingerprint and the detection of the explosive urea nitrate (UN), as a proof of principle of surface modification for simultaneous linking of identity to manipulation of explosives. By coating microscope slides with 9,10-diphenylanthracene (DPA), p-dimethylaminobenzaldehyde (p-DMAB) and p-dimethylaminocinnamaldehyde (p-DMAC), a colorimetric change was observed in the presence of UN, while revealing a fingerprint with enough resolution to isolate at least 10 minutiae. This is the first step in creating point-of-care devices capable of detecting low concentrations of explosives and drug metabolites and connecting them to a fingerprint.

Laser Desorption/Ionization Mass Spectrometry (LDI-MS) of Lipids with Iron Oxide Nanoparticle-Coated Targets

Iron oxide nanoparticle (NP)-coated target plates were employed for the direct detection and analysis of low molecular weight lipids by laser desorption/ionization (LDI) mass spectrometry (MS). We have demonstrated that the use of the iron oxide NP-coated target provides a simple, direct, and rapid detection method for lipid standards and epidermal surface lipids without any cumbersome sample pretreatment as well as mass spectra that are free of background matrix peaks. Lipid standards (1-stearoyl-sn-glycero-3-phosphocholine, 1,2-dioleoyl-sn-glycerol, 1-palmitoyl-2-oleoyl-3-linoleoyl-rac-glycerol, 1,2-distearoyl-sn-glycero-3-phosphocholine) were detected as either protonated or cationated species. Clean MS/MS spectra for each lipid were also successfully obtained. Pre-MS surface cleaning of the target plates with UV-ozone treatment successfully removed organic contaminants that would interfere with the mass spectra especially in the low molecular weight region. Preliminary application of the presented target plate to the detection of endogenous lipids in latent fingerprints showed promising results and for potential use in the visualization and chemical composition determination of latent fingerprints by nanoparticle assistance.

Towards the integration of matrix assisted laser desorption ionisation mass spectrometry imaging into the current fingermark examination workflow

A wide range of fingermark enhancement techniques (FET) is currently employed to visualise latent fingermarks at crime scenes. However, if smudged, partial, distorted or absent in the National Fingerprint Database, crime scene marks may be not useful for identification purposes. In these circumstances, a technology enabling chemical imaging of both endogenous and exogenous species contained within the fingermark could provide additional and associative investigative information, to profile the suspect's activities prior to the crime. Matrix Assisted Laser Desorption Ionisation Mass Spectrometry Imaging (MALDI MSI) has proven to be such a technique, enabling investigative information to be gathered, for example, on what substances the donor has come in contact with and what they have ingested. Nonetheless, to be employed, MALDI MSI has to be validated and its compatibility with FET tested for integration into the standard fingermark examination workflow. For the first time, a direct comparison has been made between the efficiency of a range of FET and MALDI MSI under different conditions. This information will build towards validation of the technology. Also, for the first time, MALDI MSI has been successfully employed as a sequential step following fingermark enhancement using many of the currently employed FET. Additionally, known enhancers have been "re-visited" by combining them with a MALDI matrix, providing both improved fingermark development and chemical species detection via MALDI MSI. The result reported here are good indication in favour of the integration of MALDI MSI into the current fingermark examination workflow for gathering additional investigative information.