Fingerprinting in the Digital Age

Catherine MyersIndependent Research

Advisor: Gary Hauptmann

Forensic Analyst

Baltimore County Crime Lab

What is a Fingerprint?

• Ridges and furrows developed by dermal papillae

• Skin secretions• Invisible deposits• Latent vs. patent

Dermal papillae

Sebaceous gland

Eccrine sweat pore

History of Fingerprinting

• Evidence of fingerprint use in ancient civilizations• Sir Edward Henry made first classification system • First fingerprint bureau in 1901

Loop Whorl Arch

Bifurcation

Core

Crossover

Ridge Ending

Island

Delta

Pore

Collecting Fingerprint Evidence

• Method depends on surface in question– Porous v. nonporous– Light v. dark

• Dusting

• Fuming

• Chemical development

Dusting Methods

• Powder: used on metal, glass and wood– Black or white– Fluorescent

• Magnetic: used on more porous surfaces like paper

Cyanoacrylate Fuming

• Superglue placed in sealed container

• Heated to approx. 120o

• Fumes evaporate• Cyanoacrylate adheres to

solid deposits of fingerprint• View under UV light or dye

with colored stain

Ninhydrin Development• Used on paper• Paper is submersed in ninydrin, allowed to dry• Evidence is placed in a warm, humid

environment• Ninhydrin reacts with amino acids in fingerprint

residue to form Ruhemann’s purple

Fingerprints?

Digital Enhancement

• Digital prints not as detailed as silver-developed prints

• Adobe Photoshop– Color balance– Brightness– Contrast– “Dodging and Burning”

EvidenceHow to Ensure that Evidence is

Admissible in Court

• “If this is a digital image, has it been enhanced or is this the original capture with no changes to it? If it’s been enhanced, I want you to show me what you did and tell me what your training is. And did you go out of your area of expertise to do this? (McRoberts)”

• Record of camera, lens, shutter speed, illumination, camera position, and distance and angle from an object

• Audit trail to document changes made

More Safeguards

• Original photograph should be

saved separately

• Changes should be directly reproducible

• Chain of custody should be documented and preserved

SourcesAll photos obtained from www.google.com/images

Berry, John, and David A Stoney. "History and Development of Fingerprinting."Advances in Fingerprint Technology. Ed. Henry C Lee and R E Gaensslen. 2nd ed. N.p.: CRC Press, 2001. 1-41.

Lee, Henry C, and R E Gaensslen. "Methods of Latent Fingerprint Development." Advances in Fingerprint Technology. 2nd ed. N.p.: CRC Press, 2001. 105-176. McRoberts, Flynn, and Steve Mills. "Digitized Prints can Point Finger at the Innocent." Chicago Tribune 3 Jan. 2005. 19 Dec. 2006 <http://www.truthinjustice.org/digitized-prints.htm>.

O'Connor, Tom. Fingerprints and Trace Evidence. 26 Dec. 2004. North Carolina Wesleyan College. 14 Nov. 2006 <http://faculty.ncwc.edu/toconnor/315/315lect05.htm>.

Prabahakar, Salir, and Anil Jain. "Fingerprint Identification." Biometrics Research. Michigan State University. 2 Nov. 2006 <http://biometrics.cse.msu.edu/fingerprint.html>.

Ramotowski, Robert S. "Composition of Latent Print Residue." Advances in Fingerprint Technology. Ed. Henry C Lee and R E Gaensslen. 2nd ed. N.p.: CRC Press, 2001. 63-04. Reis, George. Digital Image Integrity. 2004. Adobe. 19 Dec. 2006<http://www.adobe.com/digitalimag/pdfs/digital_image_integrity.pdf>.

Scientific Working Group on Imaging Technologies. Vers. 1.1. Feb. 2001. Florida Division of the International Association for Indentification. 19 Dec. 2006 <http://www.fdiai.org/images/SWGIT%20guidelines.pdf>.