Unit Two Forensic Science Notes 2.1 Fingerprint Analysis

Personal Identification The Bertillion System The Bertillion System of anthropometry –based on a detailed series of measurements and photographs. –based on the idea that the human bone system remained fixed after 20 years of age

Personal Identification The Bertillion System

Clumsy, cumbersome and didn’t really work all that well…..

Personal Identification - fingerprints Francis Galton Proposed assigning fingerprints to three main groups Demonstrated that fingerprints remain unchanged from year to year.

The 3 Fundamental Principles of Fingerprints 1) A fingerprint is an individual characteristic. 2) A fingerprint will remain unchanged throughout the lifetime. 3) Fingerprints have general ridge patterns that permit them to be systematically classified.

Fingerprint Identification A fingerprint is identified by –Pattern –Ridge Count –Minutiae

Fingerprint Patterns

Friction Ridges On the surface of the hands and feet are raised surfaces called friction ridges. A friction ridge is the raised portion of the epidermis, consisting of one or more connected units from the sweat glands.

Which creatures, besides primates, like humans, have fingerprints?

Which is the non-human print?

Friction Ridges Friction ridge patterns form during fetal development. –Their unique patterns are due to genetic and environmental differences. Even identical twins don’t have the same fingerprints. –This is due to random effects during fetal development.

Friction Ridges Friction ridges patterns persist throughout life -barring scarring or injury -until decomposition of the skin following death. Francis Galton (wrote Finger Prints, 1892)

Fingerprints A fingerprint is an impression of the friction ridges of the finger. Fingerprints may be deposited in natural secretions (consisting primarily of water, perspiration, amino acids, and oil) or they may be made by ink or other contaminants transferred from the friction ridges.

Fingerprint Classification Is used to categorize fingerprints into smaller groups based on general ridge formations –It permits filing and retrieval of paper records in large collections –It is used primarily as an exclusion tool rather than to identify an individual Allows the fingerprint examiner to search for an unidentified fingerprint within a specific section of the fingerprint file rather than having to search the whole file

Fingerprint Classification In the Henry system of classification, there are three basic fingerprint patterns: Arch, Loop and Whorl. This system applies a mathematical formula based upon the presence of the whorl pattern 1 + (R. Index+ R. Ring + L. thumb + L. Middle + L. Pinky) = Primary Grouping 1 + (R. Thumb+ R. Middle + R. Pinky + L. Index + L. Ring )

Fingerprint identification The process of comparing questioned and known friction skin ridge impressions to determine if they are from the same finger or palm. A known print is the intentional recording of the friction ridges, usually with black printer's ink. Friction ridges can also be recorded digitally using a technique called Live-Scan.

Automated Fingerprint Identification System - AFIS A system used for automatically matching one or many unknown fingerprints against a database of known and unknown prints. AFIS is primarily used by governmental agencies for criminal identification purposes – identifying a person suspected of committing a crime –linking a suspect to other unsolved crimes.

Automated Fingerprint Identification System - AFIS To match a print –a fingerprint technician scans in the print in question –computer algorithms are used to mark the minutiae, cores, and deltas detected on the print –The system provides fully automated searching of print features

Fingerprint Results Inclusion –The prints originated from the same finger Pattern Ridge Count Minutiae

Fingerprint Results Exclusion –The prints did not originate from the same finger Pattern Ridge Count Minutiae

Fingerprint Results Inconclusive –One of the prints lacks enough detail to be used for comparison

Matching Errors Fingerprint matching errors can be of two types – Type I (false positive) – Type II (false negative)

Type I Error The determination that two sample fingerprints from different people originated from the same person. –Mistaken identification From Madrid bombings

Brandon Mayfield and Madrid bombing Brandon Mayfield is an Oregon lawyer who was identified as a participant in the Madrid bombing based on a so-called fingerprint match by the FBI. The FBI Latent Print Unit ran the print collected in Madrid and reported a match against one of 20 fingerprint candidates returned in a search response from their IAFIS—Integrated Automated Fingerprint Identification System. The FBI initially called the match "100 percent positive" and an "absolutely incontrovertible match". The Spanish National Police examiners concluded the prints did not match Mayfield, and after two weeks identified another man who matched. The FBI acknowledged the error, and a judge released Mayfield after two weeks in May In January of 2006, a U.S. Justice Department report was released which faulted the FBI for sloppy work but exonerated them of more serious allegations. The report found that misidentification was due to misapplication of methodology by the examiners involved: Mayfield is an American-born convert to Islam and his wife is an Egyptian immigrant, not factors that affect fingerprint search technology. On 29 November 2006, the FBI agreed to pay Brandon Mayfield the sum of $2 million. The judicial settlement allows Mayfield to continue a suit regarding certain other government practices surrounding his arrest and detention. The formal apology stated that the FBI, which erroneously linked him to the 2004 Madrid bombing through a fingerprinting mistake, had taken steps to "ensure that what happened to Mr. Mayfield and the Mayfield family does not happen again."

Type II Error The determination that two fingerprints originating from the same person did not originate from the same person.

The Arches

The Loops

The Whorls

The Accidentals