The following general fingerprint information is provided as a guide. Fingerprint science is extremely complex and variable. Always consider consulting an expert before thinking about challenging one in Court.
A qualitative (clarity) and a quantitative (count) analysis occurs resulting in a value being given to a fingerprint impression or image. For a fingerprint to be of use for identification purposes the quality and quantity of features must meet or surpass the sufficiency threshold of the examiner.
Yes, almost everything about the friction ridge examination process is subjective.
The analysis is subjective – No two examiners will see and/or value the features the same way in a questioned print.
The comparison is subjective – No two examiners will compare the questioned print to another print the same way.
The evaluation is subjective because it is based on data discovered in the analysis and comparison phases of the friction ridge examination process. Additionally, each examiner has different thresholds and ethical standards.
The only way to address the subjectivity in the friction ridge examination process is to properly document the entire friction ridge examination process in a transparent and understandable manner.
The only thing objective about a friction ridge examination process is the process itself, and only IF the process is formalized into a standard operating procedure created by the organization that employs the examiner.
No: Fingerprint details are broken down into three levels.
- Level One: Ridge path (Patterns)
- Level Two: Coarse ridge features (Sometimes called points)
- Level Three: Edge features, Pore location and structure, Incipient detail in the furrows.
Each one of these dimensions are variable in both quality and quantity. The aggregate of these evaluations result in a comparison to a personal sufficiency threshold before determining the value of a given fingerprint.
Not quite. Not only must a latent print have sufficient clarity and quantity of information, the known print must also have sufficient clarity and quantity of information. Then a sequence of friction ridge information must be present in both the unknown impression and in the known impression. The amount of continuous agreement must meet or exceed an examiners personal sufficiency threshold before the origin of the impression can be identified.
Yes. From time to time, level two dissimilarities appear in prints. These dissimilarities must be accounted for in each and every case. If the latent print is robust and there is one dissimilarity, the dissimilarity can be accounted for by the overwhelming amount of agreement everywhere else in the print. If the latent print is marginal and there is the presence of a level two dissimilarity, the examiner must be able to explain it’s presence (not by guessing) or the examiner must accept the possibility the prints did not originate from the same source.
Also, examiners are often confronted with deviation or distortion in latent prints. The deviation must be within the tolerances afforded to flexible friction skin.
Yes, there are many reasons for this. Considerations usually include knowledge, training, mentoring, amount of experiences (case work) an examiner has, skill, and ability in applying the science to name a few. This is to be expected due to the subjective nature of the friction ridge examination process.
During the latter part of the 20th century, the number of points required was thought to be around 12. The origin of the 12 point threshold is thought to have started back in the early 1900’s when fingerprints replaced the less reliable Bertillon system of anthropological measurements as a means of reliable personal identification. In the Bertillon system there were 11 different anthropological measurements that were taken of an individual. The system lost favour when two brothers were processed and found to have indistinguishable measurements. Legend has it that fingerprints required the 12 points to be one better than the 11 measurements in the Bertillon system. In any case, it was a dogmatic number arrived at by various organizations and practitioners as a quality assurance measure but it had little to no science behind it.
There were many attempts to validate the requirement for 12 points. Various scientists and statisticians attempted to evaluate the likelihood that 12 points of agreement could be found from different donors. Each of these validation studies was flawed in some way or another but on a heuristic level they all showed how unlikely it would be to find two different donors with 12 points of agreement in any of their fingerprints. The least generous attempt at a level two validation study was conducted in 1892 by Sir Francis Galton who came to the conclusion that the chance of finding 12 points in two different donors = 9.54 x 10 to the 7th power. Or better stated 1 in 954 million! Now, break that number down further by dividing by 10 (fingers per person) = 1 in 95.4 million individuals and then apply that to the current population of Canada. You end up with approximately 1 in 3 times the number of people in Canada!
Every other attempt at trying to ascertain the likelihood that two different donors could have the same 12 points of agreement proved significantly more unlikely. These studies only took into account the level two features of a fingerprint and not the level one or three features. If one was to include such features in a study we wouldn’t have any difficulty understanding uniqueness at all.
So really, how many “points” do we require to identify a print? It depends; it depends on the clarity of the impression or image and it depends on how much information is visible and demonstrable. It also depends on several other considerations such as intuition and specificity. A large fingerprint sometimes has very little value and the opposite is also true. In any case, an examiner will look at the quantity of all three levels in the spectrum of detail that is both visible and demonstrable in a given print, and then consider the quality of those features before making a suitability determination. The examiner then analyzes and compares those features with the known print. If those features are present and in continuous sequence with both sufficient quantity and quality, AND if the features are found to be within the tolerances of deviation afforded to the flexible nature of friction skin, a conclusion of identification will be made.
Yes and no: Coarse ridge features and ridge paths are persistent throughout life and only usually change due to growth and\or injury. The smaller level three features can change over time due to aging and physiological changes in the individual.
Yes: Palm prints are born of the same science that applies to fingerprints. In Canada, the case Regina Vs. Nickel (1956), 18 W.W.R. 688 (Alta. Sup. Ct.) º suggested that palm prints and fingerprints were ubiquitous for the purpose of personal identification.
Never. Fingerprints develop in utero in the first trimester of life. They are believed to be born of both genetic and morphological pressures during the early development stages. The speed and timing at which the cells divide and multiply, along with the way the cells attach themselves to their neighboring cells during this rapid growth period cause significant differences between the fingerprints of twins. Once the fingerprints have finished growing (the point of differentiation) they remain persistent in the individual until an advanced state of decomposition after death.
AFIS is the Automated Fingerprint Identification System. Canada has a national AFIS run by the RCMP. On the AFIS are stored various fingerprint records that are broken down into two main categories; known records and unresolved latent crime records: Known records are the fingerprints and palm prints of people who are known such as those associated to criminal records, refugee claimants, and temporary residents throughout Canada. The RCMP also maintain latent fingerprint and latent palm print records submitted to them by law enforcement agencies throughout Canada.
In addition to the RCMP AFIS there are other several other local and regional AFIS and their respective databases throughout Canada.
Yes and no: When an AFIS search is initiated from a live scan system to determine if someone is providing their correct identity, the response of the search against the known person database is automated and the results are provided in the form of a narrative. (In most cases)
All crime scene fingerprints and palm print records are created, searched and saved by a trained expert. If those experts find a matching record they will undertake an ACE-V process (Analyze, Compare, Evaluate, Verify) before releasing identity information. Each law enforcement agency has their own process that suits their reporting methodology.
When a known record is searched against the crime scene fingerprint or palm print database, a trained expert will again undertake an ACE-V process (Analyze, Compare, Evaluate and Verification) before releasing the information. The conclusions of one examiner should always be verified before the information is released to investigators.