Composition differs between individuals› Age, health, diet, medication

Ninhydrin reacts with amino acids found in sweat› Dependent on pressure, contact time &

quantity

High variability, low certainty

Ninhydrin› Complete degradation after 60 minutes

DFO› Complete deterioration after 3 hours

Indanedione› 80% degradation after 60 minutes

Amino Acids are water soluble › DFO & Ninhydrin cannot be used on surfaces

that have been exposed to high moistureESDA Processing and Latent Fingerprint Development: The Humidity EffectMyriam Azoury M.Sc. ; Rachel Gabbay M.Sc. ; Drorit Cohen B.A. ; Joseph Almog Ph.D.Journal of Forensic Sciences  Volume:48  Issue:3  Dated:May 2003  Pages:564 to 580

“Fingermark detection techniques have been developed from the knowledge of the components of human skin secretions, without regard to the potential for aging of the print.” (p. 129)

Squalene› Naturally produced lipid found in fingerprints› Highly unsaturated, relatively quick oxidation

rate› Complete degradation after 9 daysNia E. Archer, Yannis Charles, Julia A. Elliott, Sue Jickells,

Changes in the lipid composition of latent fingerprint residue with time after deposition on a surface, Forensic Science International,Volume 154, Issues 2–3, 25 November 2005, Pages 224-239, ISSN 0379-0738, 10.1016/j.forsciint.2004.09.120.

No current standard protocol between crime labs

Unique environments lead to difficulty in distinguishing between prints with a set degree of certainty

Fingerprinting: non-scientific expert evidence

No known or recognized error rate› Claimed to be zero

Latent prints typically partial, smudged or otherwise distorted

No qualifications required to be considered an expert in latent print examination

http://cdn-wac.emirates247.com/polopoly_fs/1.285933.1283242587!/image/1491345025.gif

“I’ll preach fingerprints till I die. They’re infallible.”

- Massey, FBI Fingerprint Examiner Mayfield Case

“Fingerprints are absolute and infallible.”- FBI Fingerprint Examiner

Proficiency test for latent fingerprint identification › Collaborative Testing Service› International Association for Identification

Four suspect cards with all ten prints and seven latent prints given to subjects

156 people took the test, 68 (44%) correctly classified all seven latent prints

MEAGHER: The latent print is, in fact, identical with the known exemplar.

STAHL: It’s identical? MEAGHER: Yes.

STAHL: You can tell that?

MEAGHER: Yes.

STAHL: What are the chances that it’s still not the right person?

MEAGHER: Zero.

STAHL: Zero.

MEAGHER: It’s a positive identification.

Cole, Simon A., More than Zero: Accounting for Error in Latent Fingerprint Identification. Journal of Criminal Law and Criminology, Vol. 95, No. 3, 2005. Available at SSRN: http://ssrn.com/abstract=1025772

6 ½ years in jail 1997, Convicted of attempted murder

of a police officer› based on fingerprints and eyewitness

testimony Real culprit never found Exonerated by DNA evidence Resulted in the entire fingerprint unit of

the Boston Police Department being shut down

Cole, Simon A., More than Zero: Accounting for Error in Latent Fingerprint Identification. Journal of Criminal Law and Criminology, Vol. 95, No. 3, 2005. Available at SSRN: http://ssrn.com/abstract=1025772

Lawyer; Portland, Oregon Accused of the May 2004 Madrid

Bombings 2 weeks in police custody Print “positively identified” by three

independent highly qualified latent print examiners as belonging to Mayfield

Print later determined by Spanish Police to belong Ouhnane Daoud

Cole, Simon A., More than Zero: Accounting for Error in Latent Fingerprint Identification. Journal of Criminal Law and Criminology, Vol. 95, No. 3, 2005. Available at SSRN: http://ssrn.com/abstract=1025772

Recovery of latent fingerprints from skin

Fingerprint residue composition

Aging fingerprints

Understanding of the mechanisms of chemical reagents under examination conditions

Without this work, latent fingerprint recovery will continue to rely on empirical observations and experience

“We need to acknowledge that latent print identification is susceptible to

error, like any other method of source attribution, and begin to confront and

seek to understand its sources of error.”

- Simon Cole, Criminologist, University of California

Fingerprint evidence is notoriously unreliable leading to many wrongful convictions

Recovery of latent fingerprints is not a straightforward chemistry problem but is a complex scenario requiring the consideration of many interrelated factors

Highly variable science, with no standard sensitivity, error or protocol