Forensic Fingerprinting - Student Handout The first task in trying to match a print is to identifythe print as one of the general classes. Identification is the process of determining that an object is a member of a group with similar characteristics. Once the print has been identified as a member of a class type, police can immediately rule out any potential matches from a different class. For example, a print found at a particular crime scene may have an arch, but a suspect has a right pocket loop. It is immediately apparent that that suspect did not create the fingerprint found.
Another task in friction ridge analysis is to find out what individualizes a print. Individualization is the process of identifying what differentiates one specific print from all other prints. In the case of fingerprints, investigators need to be able to identify differences between fingerprints of the same class. Specific prints in ridge patterns create this individualization. Examiners look for tiny points (“minutiae”) in the pattern to individualize a print. Examples of minutiae that friction ridge skin analysts look for include places where a ridge splits in tow ridges (Bifurcation) or where a ridge ends (Ridge Ending). They also look for breaks and curves in fingerprint ridges.
An important thing to keep in mind when comparing prints is that two prints may look very similar but many not be from the same person. In order to positively match prints, all minutiae points identifiable on a lifted print must also be identifiable on the print on file. The opposite is not necessarily true. While prints on official record tend to show minutiae point well, a print found at a crime scene may be incomplete. Obviously, the more elements that match, the more dependable the identification will be.
Finally, it is also important to note that fingerprint identification is not without some controversy. Most of which has arisen following the Supreme Court’s 1993 decision holding that scientific evidence must be scrutinized carefully. While it is widely accepted that no two people have identical fingerprints, critics have pointed out that in the entire history of the fingerprint enterprise there has never been an objective study of the accuracy with which a partial print (as from a crime scene) can be matched to a known print. A related criticism is that there is no uniform standard for establishing that a match exists.
Partial print lifted from locker at crime scene.
n this activity you will compare the fingerprint found at the scene of the crime to the official print records of three of the suspects. As you compare, identify the class of each set of prints, and note what specifically about each set of prints does or doesn’t match the print from the locker. Remember – the more points of individualization you match, the more likely the positive identification.
Class of locker print: ___________________________________________
Notes on locker print: ___________________________________________
_____________________________________________________________Identification of partial print: ___________________________________ Forensic Science TT Student Handout