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Fingerprints: Forensics Final Project #1
Transcript of Fingerprints: Forensics Final Project #1
What is a fingerprint?
"An impression on a surface of the curves formed by the ridges on a fingertip, especially such an impression made in ink and used as a means of identification." - http://www.thefreedictionary.com/fingerprint
"Impressions or reproductions of the distinctive pattern of lines and grooves on the skin of human fingertips." - http://legal-dictionary.thefreedictionary.com/fingerprints
Two Basic Principles of Fingerprint Evidence
A human being's friction ridge patters, or "one of the corrugated ridges characteristic of the skin of the palmar and plantar surfaces of primates," does not change over time.
Patterns of friction ridges are entirely unique; no two patterns are the same.
Fingerprint Ridge Patterns
Fingerprint Ridge Characteristics
CASE STUDY #1:
During the early 20th century, shopkeepers Thomas and Ann Farrow of South London England were bludgeoned to death after being robbed.
Relation to Fingerprint Evidence:
Investigator Scotland Yard uncovered that one of the fingerprints on the empty cash box did not belong to Mr. or Mrs. Farrow. After being told by a milkman that he had seen two young men in the neighborhood of the Farrow house, Yard was able to track down these men, named Alfred and Albert Stratton. After fingerprinting them, Yard confirmed that the dissimilar fingerprint on the cash box was in fact that of Albert Stratton. The Stratton brothers were tried, found guilty and sentenced to death by hanging in 1905.
Why are fingerprints important? How are they useful?
Why do we leave prints behind?
A water based oil solution produced by your sweat glands coat the friction ridges of your fingerprint
These ridges hold onto a portion of the solution. As a result, when your finger makes contact with a surface, the remaining residue is a hidden print
Fingerprints have the ability to serve as pivotal evidence in a criminal investigation. Due to their individuality, they have the potential to help forensic scientists and criminal investigators ascertain the perpetrator of a crime.
Techniques for Lifting Fingerprints:
Technique #1: Dusting
"Fingers are coated with perspiration (or sweat, to be simple about it). All the oiliness of your stubby little digits create latent prints on everything you touch; that’s the stuff that powders pick up.
Dusting involves some sort of implement and a powder, like aluminum or magnetic powder . The movement you make with your wrist depends largely upon the surface, the tool and the powder you’re utilizing for the task." - http://forensicoutreach.com/from-super-glue-to-dusting-four-phenomenal-ways-to-lift-fingerprints/
Technique #2: Superglue Fuming
"A man named Fuseo Matsumur determined that using fumes from the Superglue (or cyanoacrylate adhesive) constituted a reliable fingerprint recovery method." - http://forensicoutreach.com/from-super-glue-to-dusting-four-phenomenal-ways-to-lift-fingerprints/
Technique #3: Electroluminescent Fingerprinting
"Electroluminescence is the most recent method to recover fingerprints (the announcement was only made in August 2012). A given fingerprint is pressed onto an electrode which is either composed of indium tin oxide or a stainless steel sheet. Then, the electrode is immersed into a special chemical solution. When a voltage is applied to the electrode, the fingerprint lights up — giving off a wondrous and luminescent glow that shows the impression in exquisite detail without any damage." - http://forensicoutreach.com/from-super-glue-to-dusting-four-phenomenal-ways-to-lift-fingerprints/
Technique #4: Ballistic Fingerprinting
"Very recently scientists developed a method which relies on the subtle corrosion or breakdown of metal surfaces to determine what a given impression looked like.
Chloride ions in our sweat acts like a chemical agent against casings; and of course, these ions are present in our sweat — which is how we leave latent prints. If you can take a closer glimpse at the part the ions corrode, you can vizualise the patterns. Access to 2500 volts means you can pass an electric field through the metal. Add some fine conducting powder to the mix, and it’ll stick to the corroded areas." - http://forensicoutreach.com/from-super-glue-to-dusting-four-phenomenal-ways-to-lift-fingerprints/
Problems with Fingerprint Evidence
A fingerprint must practically be perfect for it to be advantageous in a criminal investigation
If a fingerprint is smudged or only a partial print, it loses both its usefulness and credibility
65% of the population demonstrate looped fingerprints
30% of the population demonstrate whorled fingerprints
5% of the population demonstrate arched fingerprints
CASE STUDY #2: The Atlanta Twin Murder
In 2008, Donald Smith of Gwinnet, Georgia, was convicted of allegedly carjacking and murdering a preschool teacher. Smith matched all of the witness accounts and was supposedly caught by a surveillance camera. While being interrogated, Donald Smith insisted that he was not the perpetrator and it was in fact his twin brother, Ronald Smith.
Relation to Fingerprint Evidence:
When the fingerprint evidence found at the crime scene was examined, it revealed an exact match with that of Ronald Smith. Ronald confessed to the crime and Donald Smith was set free. The individuality of fingerprint evidence was critical in this case, to the extent that it could tell a pair of identical twins apart.
Bergman, Paul. “Fingerprint Evidence in Criminal Cases.” NOLO Law for All. Retrieved December 16, 2013, from http://www.nolo.com/legal-encyclopedia/fingerprint-evidence-what-you-need-29818.html
2. “Fingerprint evidence is used to solve a British murder case.” (2013). The History Channel website. Retrieved December 16, 2013, from http://www.history.com/this-day-in-history/fingerprint-evidence-is-used-to-solve-a-british-murder-case
3. The Forensic Outreach Team. “From Super Glue to Dusting: Four Phenomenal Ways to Life Fingerprints.” Forensic Outreach. Retrieved December 16, 2013, from http://forensicoutreach.com/from-super-glue-to-dusting-four-phenomenal-ways-to-lift-fingerprints/
4. Ferran, Lee. “Rare Twin Murder Case Echoes Bizarre Fingerprint Origins.” ABC News. Retrieved December 16, 2013, from http://abcnews.go.com/TheLaw/atlanta-twin-murder-case-echoes-fingerprint-origins/story?id=9909586