Thanks for the question.
Many factors come into play regarding the longevity of fingerprints:
- Age of the person leaving the fingerprints.
- Cleanliness of finger tips.
- Properties of the surface where fingerprints are left (porous and
- Atmospheric and environmental factors.
- Temperature and Humidity.
- Quality of the person's fingertip ridge skin - scars, warts etc.
Due to these factors "the age of a set of fingerprints is almost
impossible to determine. Therefore, defendants often try to explain
away evidence that their fingerprints were found at crime scenes by
testifying that they were at the scene and left the prints at a time
other than the time of a crime"
let's take a look at the above factors.
TechnologyReview.Com has an article discussing a simple chemical
technique that helps investigators turn faint prints to more readable
source of evidence:
"All fingerprints are not created equal. A print left by an adult can
last for months, for instance, while those left by children are
notoriously quick to degrade. But only recently has the chemistry
behind these differences come to light, and scientists at the Y-12
National Security Complex, a National Nuclear Security Administration
facility in Oak Ridge, TN, have devised a surprisingly simple chemical
technique that renders even exceedingly faint prints more readable.
Good fingerprints, researchers at neighboring Oak Ridge National
Laboratory discovered several years ago, are made primarily of sebum,
the oil secreted by glands on the scalp, face, back, and chest. This
material is transferred to the fingertips whenever a person touches
his or her scalp or face, and it is transferred once again-as
fingerprints-when the person touches a smooth surface. The fatty acids
in sebum seal in moisture and give fingerprints longevity. By
contrast, the worst fingerprints are left by those who have just
washed their hands and by young children who have not yet begun to
secrete sebum. Their fingerprints contain mainly salts and protein
molecules dissolved in water, which dries up within hours, leaving
virtually unreadable prints.
Last year Y-12 scientists Linda Lewis and Bob Smithwick discovered
that by exposing such fingerprint ghosts to acetic acid, a chemical
found in vinegar, they can regenerate the prints, making it possible
to apply the chemical-fuming and dusting techniques employed to
highlight and preserve good prints. Using their method, Lewis and
Smithwick have revitalized previously unreadable prints after more
than a month of dehydration.
The acetic acid technique "may be a very viable method of regenerating
older prints," says Bill Doyne, a forensic expert with the U.S. Army
Criminal Investigation Laboratory. And for crime scene investigators,
that find of a better method could be a boon that leads to more
Raleigh Blasdell's paper was discussed at the Illinois Junior Science
and Humanities Symposium and proves the difference
in longevity of the latent fingerprints of children vs adults. Tests
prints were done upon glass surfaces:
"The Longevity of the Latent Fingerprints of Children vs Adults"
"Abstract: The purpose of this project was to determine if there was a
difference in the longevity of the latent fingerprints of children vs
adults. It is generally believed that a subject's age does not affect
the evaporation rates of fingerprints. However, based upon a recent
criminal investigation of child abduction, it was hypothesized that
children's latent fingerprints do not last as long as those of adults.
Participation in this study was voluntary and informed consent
obtained. A total of 97 subjects pressed their fingers on glass slides
and their latent fingerprints were lifted one, three, five and seven
days later. A comparison was then made between the longevity of the
prints of children vs adults. Almost all of the adult prints were
still present on day seven. Of the children's prints, 20 percent were
unclear on day three; 54 percent were unclear on day five; and 76
percent were unclear on day seven. This has implications for law
enforcement and forensic science in that time may become a critical
variable in criminal investigations requiring the lifting of latent
fingerprints of children."
From the Technical Report in the Mar/Apr 1997 issue of the Journal of
Forensic Identification tilted: ""Life of latent prints":
"Unless there is a witness to the offender handling the firearm, there
is no way of knowing when the firearm was touched by him/her. It could
be days, months, or years since the firearm was handled by the
Professor Andre A. Moenssens has studied latent print age
determination extensively. He stated at the 57th Annual Conference of
the International Association for Identification (Milwaukee, WI,
1972), ?I would simply say that I cannot tell with any degree of
precision because there is no known way to determine positively, or to
even closely approximate by opinion testimony, the length of time a
latent has been on an object. You can sometimes establish the length
of time a print has been on an object circumstantially, but not
Charles R. Midkiff has examined the results of tests done by others.
He states ?from studies and cases examined, it is apparent that wide
variations exist in the ability of a latent print to survive, even
under rather harsh conditions. Development of a latent print at a
crime scene is no guarantee of its having been recently placed. In
addition, the studies suggest that no reliable indication of a print's
freshness can be obtained from its rate of development or appearance
after it is developed. Speculation or court testimony concerning the
time when a latent print was placed may be hazardous to the reputation
of the examiner?
Regarding fingerprints that are taken by law enforcement agencies when
a criminal or suspect (depending on the laws applicable in the
specific country or state) is taken into custody or when the military
enlists new recruits - the prints were historically taken with
printer's ink, a roller and a slab and stored on a card. This somewhat
primitive method ensures that fingerprints will last 100's of years
(at least) and can be easily scanned into digital form and stored in
computer databases (optical or magnetic forms).
England's oldest Printed Document, for instance, dates back to 1476
and was NOT printed on paper manufactured with longevity in mind, also
the document did not enjoy storage in temperature and humidity
controlled environments such as fingerprints do nowadays.
More modern methods use methods like Livescan's inkless process:
"As a result of legislation passed in late 1997, the California
Department of Justice ("DOJ") has developed an automated background
check process that requires digitized fingerprints, called Live Scan.
Live Scan is an inkless fingerprinting process. The fingerprints are
electronically transmitted to the central computers at the DOJ in a
matter of seconds, instead of the days required to send hard copy
fingerprint cards through the mail."
This means fingerprint records in digital form technically last forever.
To summarize: All fingerprints taken from a suspect or criminal or
member of military forces are now either immediately computerized OR
will be in due course converted from ink into digital form and will
"The FBI's Integrated AFIS (IAFIS) in Clarksburg, WV has more than 46
million individual computerized fingerprint records for known
criminals. Old paper fingerprint cards for the civil files are still
manually maintained in a warehouse facility (rented shopping center
space) in Fairmont, WV, though most enlisted military service member
fingerprint cards received after 1990, and all military-related
fingerprint cards received after 19 May 2000, have now been
computerized and can be searched internally by the FBI. In some
future build of IAFIS, the FBI may make such civil file AFIS searches
available to other federal crime laboratories.
All US states and most larger cities have their own AFIS databases,
each with a subset of fingerprint records that is not stored in any
other database. Thus, law enforcement fingerprint interface standards
are very important to enable sharing records and mutual searches for
identifying criminals. "
Much more interesting information on the subject of fingerprints can be found here:
Any Clarifications needed? Don't hesitate to ask.
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