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King County Sheriff

Leadership, Integrity, Service, Teamwork

   King County Sheriff

Emergency: Call 9-1-1

Call (206) 296-3311 24-hours to report a neighborhood problem or a crime that is not an emergency.


King County Courthouse
516 Third Ave
Room W-150
Seattle, WA 98104
(206) 296-4155
TTY Relay: 7-1-1
sheriff@kingcounty.gov

 

 

 

 

 

 

 

 

 

 

 

The Basics of Fingerprint Science

The two fundamental principles of fingerprint identification are that fingerprints are permanent and unique: fingerprints never change and no two fingerprints are the same.
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Permanence:
Fingerprints are formed before birth, and while they grow larger throughout a person’s life, their basic structure remains constant.  They can be temporarily obscured when the skin is damaged; but once healed, the ridges grow back in the exact same pattern.  Even when a fingerprint is permanently scarred, there is almost always sufficient detail around the scar to allow for a positive identification. 

Uniqueness:
Fingerprints are made up of skin ridges - or friction ridges - that have unique pattern formations.  Examiners are able to evaluate and compare the flow or ridges, the relationship between ridge endings (or minutiae points), and other details to make an identification.  Beside being unique in fingerprints, ridge detail is also unique in the palms of hands and the soles of feet.

Fingerprints vs. DNA
Both fingerprint identification and DNA analysis have proved to be valuable tools for personal and criminal identification.  However, fingerprint identification can be more accurate than DNA analysis.  Even identical twins that look exactly alike and have the same DNA structure will always have different fingerprints!  This is because fingerprints are formed in the womb, where movements and natural growth randomly create the characteristics.