It's
all in the fingertips
Exploring the history and technique of fingerprinting
:
by Dishan Joseph
 No crime is hundred percent fool proof. No matter how meticulous the
criminal and how much they attempt to distort evidence and mislead the
Police, often one fingerprint can give a major breakthrough to
detectives. Forensic science has assisted in the accurate prosecution of
criminal offenders. Today crime scenes are patiently combed for
fingerprints, hair, skin particles and human secretions apart from other
vital material evidence.
Fingerprints are left by the friction ridges on the finger, with
sweat from the eccrine glands. Often prints are found on glass, polished
stone and metal surfaces. Our fingertips have friction ridges mainly to
transmit to our sensory nerves, in the course of 'fine texture
perception' by touch. Even our soles and toes carry friction ridges
which leave behind a unique print. Decades ago hospitals used to take
impressions of infants footprints for identity records! During both
World Wars allied combat pilots had their footprints taken and recorded,
so that in case of a serious crash that results in a burnt body, the
feet would yield better id as they were covered by thick boots. We all
know that facial features change with age, but fingerprints remain
persistent.
Fingerprint identification takes place when two sets of friction
ridge impressions are compared (Dactyloscopy).Chinese records of the Qin
dynasty show that handprints were used to apprehend burglars. The
practice was followed in 14 Century Persia. It was in 1892 that Sir
Francis Galton, an anthropologist first published a paper outlining the
unique print we carry on each finger. Incidentally he was a cousin of
Charles Darwin. An Argentinean Policeman named Juan Vucetich made the
first criminal fingerprint in 1892. Subsequently in 1901 Sir Edward
Henry, who served as an Inspector General in the Bengal Police, set up
the first systematic process to collect, classify and document
fingerprints. This system worked on three patterns of fingerprints loop,
whorl and arch.
Primary source
The importance of fingerprints became very evident in a case in
Leavenworth, Kansas, USA. The Prison Warden was astonished to find out
that two prisoners had the same name, William West. Amazingly both men
had the same body weight and height (known then as Bertillon records)
and also resembled each other, but were total strangers! Rapid changes
were made to take fingerprints of all inmates and the prints became the
primary source of identifying a person. In 1908 the first Fingerprint
card was used by law enforcement agencies. The US Courts began accepting
fingerprints as legal evidence in 1911. In Mark Twain's book "Life on
the Mississippi" (1883) a murder is identified by his prints.
As legal proceedings took a new turn, Thomas Jennings became the
first murderer in criminal history to be tried and convicted based
solely on the evidence of his fingerprints , by the Supreme Court of
Illinois. Jennings was executed in1912. Another spectacular stage coach
robbery in Nevada in 1917 necessitated the use of palm prints. Once
again justice was meted in the conviction of Ben Khul. The Federal
Bureau of Investigation set up its official ID Division in 1924 and
today can boast of a collection of 700 million individual fingerprints.
Prints were originally taken with black ink impressions but today done
on a glass plate with digital input, known as a Live Scan. In this
process the prints are captured by means of optical, ultrasonic and
thermal imaging. Since 2010 non contact 3D scanners are used to capture
fingerprints.
The scientific study of fingerprints is Dermatoglyphics. At most
crime scenes forensic experts search for latent prints, these are
fragments of fingerprints left on surfaces (ie- firearm) and remain
invisible to the human eye.
These have to be dusted by using powder, chemical reagent or a
special flashlight. Latent prints are transferred to surfaces by the
criminals sweat or ink, oil, blood and grease like substances that
originate during an aggravated assault or robbery. Visualization of
distorted and smudged prints can be done electronically.
Another aspect of investigations is to look for "plastic prints"-
fingerprints that have been left encrusted on surfaces such as wax, clay
(during burglaries at factories and farms) and thick oil deposits during
car thefts. These prints need no enhancements. There was a brilliant
case of detection when a man was sending pictures of a stolen item via
his mobile phone, when by mistake his fingerprint was also
"photographed" and transmitted in the image, which led to his arrest!
This is often seen in Smart phones that use biometric means of
authentication. In today's corporate world many companies use
fingerprint acquisition systems to punch in attendance and also grant
access to restricted areas, that require prior security clearance. Back
in 1858 Sir William James a British Magistrate in India began using
fingerprint impressions on native business contracts.
Facial identification
In many cases Police have to identify dead persons, whose bodies are
found in marshlands, riverbanks and inside dark caves. When facial
identification is not possible, they have to take fingerprints from the
decomposing body. Major advances in this technique were made by Adam
Savage and Jamie Hyneman using a photographic sensor that can record and
transmit the vital prints. Even identical twins, who share the same DNA
don't have the same fingerprints. It is an amazing fact that
fingerprints can remain intact on given surfaces and be traced even in
crime scenes involving a fire, as the prints can withstand heat up to
almost 600 degrees Celsius owing to the eccrine secretion from the skin,
which is heat resistant in varying conditions.
In 1995 Detectives of the Knoxville Police Department made an
interesting discovery. They found that fingerprints of children don't
remain long, as they tend to evaporate. This is attributed to the lower
percentage of fat in their sweat, in comparison to adults. Therefore
missing children cases must be handled with detailed care in terms of
crime scene. The fingerprints of tobacco users will show traces of
nicotine in a Police laboratory. The International Fingerprint Research
Group (IFRG) which is made up of law enforcement agencies from America,
Canada, Europe, Australia and Israel pool their resources and continue
to update new methods in fingerprint detection. As of 2012 Interpol has
150,000 sets of criminal prints from over 190 countries.
Pic - howitworksdaily.com |
