DCSIMG

POSTAL INSPECTORS: THE SILENT SERVICE
An Exhibit at the Smithsonian National Postal Museum
 
Smithsonian National Postal Museum
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Home
The Silent Service
Postal Crime
Silent but Effective
Surveyor-Inspector
Robbing the Mail
Unexpected Duties
Bombs in the Mail
You Solve the Case
Reading Fingerprints
Make a Match
Handwriting Analysis
Creating a Profile
Fake Money Orders
Don't Be a Victim
In Memoriam
Protecting You Now
Resources
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READING FINGERPRINTS





Latent fingerprints are clearly revealed on this bottle




Image: Latent fingerprints are clearly revealed on this bottle
 

Investigators have used fingerprints to identify criminals for over a century. While other visible characteristics may change over time, fingerprints do not. Fingerprints are the residue of perspiration secreted along the tops of “friction ridges” on fingertips. When people touch something, they leave what is called a “latent” print. Latent prints are not usually visible to the naked eye.

Analysts reveal latent prints by using powders, special lighting, or chemicals, depending on the surface on which the print was left. They look at specific areas of prints for points that match between a suspect’s fingerprint and the latent print from the crime scene. There is no international standard for the number of points that result in an identification match. Postal Inspection Service technicians look for seven to nine points before declaring a match.

 

Can You Match the Print to the Right Suspect?

Illustration of nine matching points between known and latent prints

A fugitive has left his thumbprint on this map which was found at the scene of a crime. This is an important clue! Postal inspectors have three suspects and need to use the print to determine which of these individuals should be charged with the crime.

Image (left): Illustration of nine matching points between known and latent prints


Can you help the inspectors find the thieves?


Use the known thumbprints on the posters below to match the latent print found in the bottom right corner of the map above.

Mug shot from Walter Legenza's Wanted poster
Walter Legenza's Wanted poster

click to enlarge
Mug shot from Peter Gusenberg's Reward poster
Peter Gusenberg's Reward poster

click to enlarge
Mug shot from Charles P. Clouse's Reward poster
Charles P. Clouse's Reward poster

click to enlarge
Thumbprint from Walter Legenza's Wanted poster
Walter Legenza's Wanted poster
Thumbprint from Peter Gusenberg's Reward poster
Walter Legenza's Wanted poster
Thumbprint from Charles P. Clouse's Reward poster
Walter Legenza's Wanted poster
Images (above):
Mug shot and thumbprint from Walter Legenza's Wanted poster
Images (above):
Mug shot and thumbprint from Peter Gusenberg's Wanted poster
Images (above):
Mug shot and thumbprint from Charles P. Clouse's Wanted poster
   
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Acknowledgements

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