Dactyloscopist

Fingerprint expert

Evidence

• 3 different kinds of fingerprints– Latent Prints– Patent Prints– Plastic Prints

Latent Prints

• A chance or accidental impression left by skin on a surface

• Chemical, Electronic, and physical processing techniques show visualization of the invisible print

• Print comes comes from sweat, motor oil, blood, paint, ink…

• Very valuable physical evidence

Latent Print

Patent Prints

• Friction ridge impressions of unknown origins • Transfer from a foreign material on a finger

onto a surface• Visible• Photographed rather than lifted• Ex: ink, dirt, blood…

Patent Prints

Plastic Prints

• Friction ridge impression from – Finger– Palm– Toe– FootKeeps the shape of the ridge detailEx: melted candle wax, thick greaseVisible and doesn’t need photography

Plastic Prints

Fingerprint Capture

• The machine mainly determines the difference in the ridges and the valleys

• Two kinds of readers– Solid-state fingerprint reader– Optical fingerprint reader

Classifying fingerprints

• 4 different kinds of fingerprints: – Arch– Loop– Whorl– Tented Arch

Arch

Loop

Whorl

Tented Arch

Case Study: Conviction Through Enhanced Fingerprint Identification

• In 1990 an unknown assailant sexually molested and fatally stabbed a young woman. The only evidence was a pillowcase, found next to the victims body. It had several blood stains, one stain showed some faint fingerprint ridge detail.

Investigation

• Pillowcase to the departments forensic unit for bloodstain pattern analysis

• Stains were consistent with a knife blade• Fingerprint had enough ridge detail to go

further into the investigation• Image enhancement developed likely suspects

and the the DNA proved the fingerprint match was correct

Interview

• “What kind of educational background do you have to have in order to work as a fingerprint expert?”

• “It depends, there are different levels. There is on the job training and job preparation training; NCIC National Crime Index Certification and International Association of Identification. The person with the least amount of experience has worked here for 7 years.”

• “What is a typical day like for you?”• “It depends, I examine fingerprints of

individuals that are arrested and process their identification to check their previous arrest history. I also review the work of coworkers to make sure they make proper identifications.”

• “Are you a forensic specialist all the time or do you have a "day job"?”

• “There are different shifts. There is a late unit and a temperate unit which is 24 hours. There are three 8 hour shifts each day. There is a shift from 4am to 3 pm.”

Resources• http://images.google.com/imgres?imgurl=http://www.fdle.state.fl.us/CrimeLab/im

ages/fingerprint

• http://www.wilsonnc.org/userimages/image/00000023_image002.jpg • http://en.wikipedia.org/wiki/Fingerprint#Patent_prints• http://static.howstuffworks.com/gif/safecracking-keypad.jpg• http://people.pwf.cam.ac.uk/jw566/research/photex/application/images/finger1.

jpg• http://www.crimeandclues.com/92dec001.htm