MXRF SYSTEM X-ray Tube / X -ray source Detector Sample chamber Analyzer Computer Soft ware

MXRF SYSTEMMXRF SYSTEM

• X-ray Tube / X -ray source

• Detector

• Sample chamber

• Analyzer

• Computer

• Soft ware

MMicro-X-ray fluorescenceicro-X-ray fluorescence

MMicro-X-ray fluorescenceicro-X-ray fluorescence

MMicro-X-ray fluorescenceicro-X-ray fluorescence

MMicro-X-ray fluorescenceicro-X-ray fluorescence

• Examined in which the prints were imaged based on their elemental composition.

• Nondestructive technique.

MMicro-X-ray fluorescenceicro-X-ray fluorescence

• Unique prints were also detected including those containing lotion, saliva,banana, or sunscreen

• Studying demonstrates the potential for visualizing fingerprints by MXRF on surfaces

Examples of potentially troublesome substrates include: fibrous papers

textiles

Woods

Leather

Plastic

Adhesives

human skin

Wilkinson et al used synchrotron IR microspectroscopy

Koch et al. used SEM / EDS

and imaging AES.

Migron and Mandler used AES and SEM/EDS

Nolan et al used SEM

INTRODUCTIONINTRODUCTION

• Micro-X-ray – used to acquire

elemental spectra – directly image both

visible and latent fingerprint friction ridges

– via inorganic elements present in the print residue .

Materials and MethodsMaterials and Methods

1.1. A Kevex OmicronA Kevex Omicron

– energy-dispersive XRF spectrometer with a 100W molybdenum X-ray source

– monolithic polycapillary optic .– uses a Si(Li) detector – sample chamber was flushed with helium

for the analyses

Materials and MethodsMaterials and Methods

2.2. Eagle II XPL MXRFEagle II XPL MXRF

• AAn energy-dispersive XRF spectrometer n energy-dispersive XRF spectrometer using a 40W rhodium X-ray source using a 40W rhodium X-ray source

• monolithic polycapillary optic .monolithic polycapillary optic .• Si(Li) detector Si(Li) detector • The sample chamber was purged with The sample chamber was purged with

vacuum for all analyses vacuum for all analyses

Sample PreparationSample Preparation

• Two subjects supplied the fingerprints Two subjects supplied the fingerprints examined in this work.examined in this work.

• All fingerprints prepared on All fingerprints prepared on polypropylene were made using 4-mm-polypropylene were made using 4-mm-thick film sold by Chemplexthick film sold by Chemplex

Sample PreparationSample Preparation

Sample Preparation

Unique prints were detected including those

containing …….

Sebaceous Fingerprints

Fingerprints after Perspiring

Lotion

Saliva

Banana

Sunscreen on Black Substrate

Sebaceous FingerprintsSebaceous Fingerprints

• Subject #1 made a fingerprint on a Subject #1 made a fingerprint on a polypropylene film after touching the polypropylene film after touching the forehead.forehead.

• The fingerprint sample was imaged with the EDAX MXRF instrument

FIG. 1—Micro-X-ray fluorescence chlorine K–L2,3 relative intensity image

acquired from the middle portion of a sebaceous fingerprint left on poly

propylene.

Fingerprints after PerspiringFingerprints after Perspiring

Fingerprints after PerspiringFingerprints after Perspiring

FIG. 2—Micro-X-ray fluorescence potassium K–L2,3 relative intensity image acquired from a fingerprint left on

polypropylene using perspiration.

LOTIONLOTION

LotionLotion

LOTIONLOTION

• Friction ridges were detected as depicted in the total IR absorbance image IR microscopy could also be a very powerful method for detecting fingerprints and could complement MXRF results.

• Fingerprints are not evident using Fingerprints are not evident using MXRF, they might be identifiable by MXRF, they might be identifiable by IR microscopy.IR microscopy.

Saliva

The sample was imaged with the Kevex The sample was imaged with the Kevex MXRF instrumentMXRF instrument

SALIVASALIVA

• Fingerprint was detected from the potassium ,chlorine, and phosphorus present in saliva transferred to the substrate.

BananaBanana

• Subject #2 touched the moist interior of a banana after washing the hands with soap and tap water and left a fingerprint on polypropylene .

• The sample was imaged with the Kevex MXRF instrument .

BANANABANANA

• The sample consisted of some aggregates of banana residue that masked a portion of the print ridges in the potassium image.

• Similar aggregates were observed in

the sodium, magnesium, phosphorus, chlorine, and molybdenum maps, but no ridge detail was present.

Sunscreen on Black SubstrateSunscreen on Black Substrate

• subject #2 applied Neutrogena subject #2 applied Neutrogena sensitive skin sunscreen SPF 30 to sensitive skin sunscreen SPF 30 to the hands and rubbed it in until the the hands and rubbed it in until the white color could not be seen.white color could not be seen.

• made on the black paper. The made on the black paper. The sample was imaged with the Kevex sample was imaged with the Kevex MXRF instrument MXRF instrument ..

Sunscreen on Black SubstrateSunscreen on Black Substrate

• Organic active agent such as para-aminobenzoic acid (PABA) is not detectable by XRF

• Identifying sunscreen prints containing titanium or zinc oxide is straightforward.

Sunscreen on Black SubstrateSunscreen on Black Substrate

• The substrate was porous and black in color .Cyanoacrylate fuming will provide a white-colored print .

• For fingerprints on porous surfaces MXRF would provide an alternative means to image the print

Fingerprint LongevityFingerprint Longevity

• The fingerprint prepared by applying The fingerprint prepared by applying Eucerin hand lotion was analyzed a Eucerin hand lotion was analyzed a second time with the second time with the Kevex instrumentKevex instrument ~~ 7.5 months 7.5 months

• The fingerprint composed of hand The fingerprint composed of hand lotion was still readily apparent in the lotion was still readily apparent in the potassium and chlorine maps. potassium and chlorine maps.

Future DirectionsFuture Directions

• Study a larger pool of subjectsStudy a larger pool of subjects

• Determining whether certain people Determining whether certain people consistently generate prints detected consistently generate prints detected by MXRFby MXRF

ConclusionConclusion

• The potential of The potential of MXRF for MXRF for detecting both detecting both visible and latent visible and latent fingerprints fingerprints ..– A finger coated A finger coated

with a residue with a residue such as such as gunpowder might gunpowder might be detectable from be detectable from the sulfur and the sulfur and potassium content potassium content ..

• Other distinctive fingerprint examples such as those containing lotion, sunscreen, saliva, or certain food residue can be detected by MXRF based on the inorganic elemental constituents.

• The print can be identified regardless of the background color.

• Volatilization of water, oils, and other Volatilization of water, oils, and other organic components over time should organic components over time should not hinder print identification since not hinder print identification since only inorganic elements are detectedonly inorganic elements are detected

• MXRF offers a novel means to image MXRF offers a novel means to image fingerprints that should complement fingerprints that should complement the current list of tools available to the current list of tools available to forensic investigators.forensic investigators.

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