If you haven’t had the opportunity to read my prior three posts, suffice it to say that when ridges end or bifurcate (split in two), the point at which this happens is a minutia.
Google Gemini.
But what if a ridge bifurcates and immediately rejoins? Then you get a fingerprint lake, or enclosure.
Google Gemini.
No, not that kind of lake.
Fingerprint lakes. Google Gemini.
Now forensic friction ridge examiners don’t care whether the detail is a ridge ending, bifurcation, trifurcation, lake, or something else. (Well, they do.) They document what they see, and lakes (when clearly visible on both prints) are extremely helpful in identification.
But computerized automated fingerprint identification systems DO care. If the lake is only a puddle—perhaps a dot or short ridge depending on pixel/ridge width resolution—the AFIS may or may not assign minutiae. If the AFIS chooses to mark them, it will show two opposing bifurcations at either end of the lake.
But in conclusion, that’s a lake. Hope that helps. Perhaps I will explore additional friction ridge geography later.
Forensics and Law in Focus shared an article from the CBC that touched upon the number of points of similarity in ballistic comparisons. Yawn. We’ve been through points of similarity in the fingerprint world, and the same issues exist in ballistics.
Ballistics
Whether or not you believe forensic science is an oxymoron, ballistics analysis seeks to determine if a bullet (or casing) fired from a particular gun. It does this by firing a second bullet from the same gun, comparing the markings on the two bullets (or casings), and seeing if they match.
But Sara Gordon has a problem with the way these matches are determined.
“She…says there are no set standards for the minimum number of similarities needed to match bullets.”
Well, I have a problem with Gordon’s problem.
Because we’ve seen this before.
Let’s look at fingerprints
The fingerprint and friction ridge world employs a similar method. Except that instead of looking at metal markings, a computerized automated fingerprint identification system (or a forensic examiner) looks at the friction ridges and searches for minutiae. These are the points at which the friction ridges end, or bifurcate into two ridges.
Image from the U.S. National Institute of Standards and Technology.
The (really simplified) theory is that if you take a constellation of minutiae from one fingerprint, and a constellation from another fingerprint, and the constellations are the same, then the fingerprints came from the same finger.
So how do you determine if the fingerprints are the same?
Sara Gordon would love one method.
Edmond Locard enters the chat
Dr. Edmond Locard was a French forensic examiner who was active in Lyon in the early 20th century. Among other things, Locard worked with Alphonse Bertillon (yeah, that guy) and established Lyon’s crime investigation laboratory.
“If more than 12 concurring points are present and the fingerprint is sharp, then certainty of identity is beyond debate….
“If 8 to 12 points are involved, then the case is borderline….
“If a limited number of characteristic points are present, the fingerprint cannot provide certainty for an identification, but only a presumption for identification, and only a presumption proportional to the number of points available and their clarity.”
Sounds clear cut, doesn’t it? 14 points of similarity and you’re certain. 7 points, nope.
But think about it.
What if you have 20 points of similarity (more than Locard’s 12), but have one glaring dissimilarity that cannot be explained by poor print quality? Locard or no Locard, that is NOT a match.
And what if your crime scene (latent) print sample is very small and you only have 7 matching minutiae (fewer than Locard’s 8)? The late Clarence Phillips loved to show this very example. Locard or no Locard, that is a match.
Phillips enjoyed a long career in forensics with the Federal Bureau of Investigation, Printrak, Motorola, MorphoTrak…and the International Association of Identification (past President, 1986-87).
The IAI enters the chat
Before Phillips’ Presidency, and because of the various concerns about the Locard method, the IAI convened a group in 1970 to study the matter. On August 1, 1973, the IAI issued a statement (PDF) which read in part as follows:
From Scribd.
“The International Association for Identification assembled in its 58th Annual Conference at Jack-son, Wyoming, this First Day of August, 1973, based upon a three-year study by its Standardization Committee, hereby states that no valid basis exists at this time for requiring that a pre-deter-mined minimum number of friction ridge charac. teristics must be present in two impressions in order to establish positive identification. The foregoing reference to friction ridge characteristics applies equally to fingerprints, palm prints, toe prints and sole prints of the human body.”
In most other countries, present practice centers on a process (ACE-V) that admittedly has qualitative characteristics, but which is more accurate than the old 12-green 7-red system.
Back to ballistics
Returning to ballistics, if a minimum number of matching minutiae doesn’t work for friction ridges, why would it work for bullets and casings? The Death Penalty Information Center has published its concerns on the topic.
“In three dimensional toolmarks when at least two different groups of at least three consecutive matching striae appear in the same relative position, or one group of six consecutive matching striae are in agreement in an evidence toolmark compared to a test toolmark. In two dimensional toolmarks when at least two groups of at least five consecutive matching striae appear in the same relative position, or one group of eight consecutive matching striae are in agreement in an evidence toolmark. For these criteria to apply, however, the possibility of subclass characteristics must be ruled out.”
The Association of Firearm and Toolmark Examiners (AFTE) permits a more qualitative analysis from its practitioners, “sufficient agreement”—a practice that concerns the Sara Gordons of the world.
“Modern practice adds a second layer: three-dimensional surface topography acquired by confocal or structured-light scanning, processed by the Congruent Matching Cells (CMC) algorithm to produce a quantitative comparison score that supplements the optical examination. The scoring output, when converted to a likelihood ratio under the Algorithmic Comparison Score (ACS) framework, meets the ENFSI evidential-weight reporting standard now required in several European jurisdictions.”
When I talk about translation, I’m usually not talking about language translation. Trust me, my French, German, or Spanish isn’t good enough for that type of translation.
But I excel at other types of translation that help my client businesses run more smoothly.
Biometric translations
Bredemarket knows how different biometric systems “talk” differently…and how they can talk to each other.
I’m often talking about translating between different NIST-based biometric interchange standards. Because the FBI system doesn’t exchange biometric data in the same way as the DoD system, or the DHS system, or the RCMP system, or others.
“Luckily all the different standards have some basic similarities, but if you have a mobile biometric device that must submit to DOJ and DoD and DHS, you need to switch to the proper profile for each submission….
“But I’ve overcome this frustration over 30 years of immersing myself in all things biometric-translation related.”
And I may immerse myself some more. One of Bredemarket’s clients distributes software that submits to one system. What if that software has to submit to two systems? Or 20? Or 200?
But I deal with other translations too.
Stakeholder translations
Bredemarket knows the players in an identity, biometric, or technology system…and how they can talk to each other.
Any complex project will have a variety of stakeholders, each of whom speak their own “language.” My job at Bredemarket often entails allowing these people to communicate with each other.
To illustrate this, let me share a simplified example of something I shared before.
Engineers develop a biometric application.
The application has to conform to forensic standards.
The application is used by people in the field who may not know engineering or forensics, but who know conditions in the field better than engineers or forensic experts.
OK. Now write the user guide so that the field worker understands what the engineers created and captures what the forensic folks need.
This is where the inexperienced writer suffers from a failure of courage.
Let me tell you a little secret.
Most engineers can’t write the user manual. They’ll go into great detail about how the SDK references this particular process, but they can’t tell the field worker how to capture a fingerprint from a dead body that has been in the woods after a week of rain.
How has Bredemarket approached similar projects?
By asking the right questions of all the stakeholders—not just the three I mentioned here, but ALL of them including Ontario, California mayor Paul Leon (or whoever the political honcho is on YOUR project).
Then writing the draft. I won’t go into the “draft 0.5 – draft 1” mechanics here, since I’ve covered them elsewhere.
Then collaborating on the reviews, giving the draft to the stakeholders and insisting on getting timely feedback.
Then finalizing a document that allows the field worker to use the product in line with engineering and forensic advice (or advice from whoever) that the field worker understands.
I’ve performed this task—all the cool kids call this “cross-functional collaboration”—numerous times, working with everyone from sales to legal to a client’s own suppliers and end customers.
What do you need translated?
You know that your multi-department project won’t take off until someone glues the pieces together…and ensures that everyone is talking to each other.
At this moment Bredemarket is working on multiple client projects and delivering project management, strategy, writing, and other services.
This often involves translating between the different stakeholders. The outside business head doesn’t care what technical standards my client supports…but you can bet the outside technical head does.
Does your identity, biometric, or technology firm have a product marketing project that requires a lot of people to work together?
Let’s talk (for free) about how I can help. Set up a meeting below.
It is the DOCUMENTED trail of every person who accessed (“touched, moved, or stored”) a piece of evidence. The documentation is chronological and ideally logged in real time, not hours after the fact.
What could go wrong?
Let’s say that at 1:23 pm, Diana placed a piece of evidence in a locker and locked the locker. Then at 3:53 pm, Denis went to the locker, which was unlocked, and removed the evidence from the locker. Defense attorneys will have a field day with that, and may pressure the judge to state that the evidence is inadmissible because of possible tampering by an unidentified person.
Cross-Contamination
Closely related to the chain of custody is the possibility of cross-contamination. In the case of DNA, this happens when DNA from a crime scene is mixed with another person’s DNA.
I’ve told the story of the mystery female criminal whose DNA was found at crime scenes in three different countries over a decade. The only problem was that the woman’s DNA was found on the burned body of a MAN. Eventually the authorities figured out that the woman worked in a packing center specializing in medical supplies…and that her DNA had contaminated the medical supplies and ended up in the crime scene samples.
How to Minimize Errors
Forensic’s Blog suggests several ways to avoid chain of custody issues and cross-contamination. These include established and enforced procedures for handling, packaging, and labeling data; separating tasks; and establishing zones of exclusion at crime scenes.
In addition to establishment and enforcement, education is essential. (Sorrye.) Not only for the forensic professionals gathering the evidence, but for everyone who deals with the evidence…including biometric vendors and their customers.
If you need assistance in creating educational content for proper evidence handling, Bredemarket can help. Talk to me.
Bredemarket: Services, Process, and Pricing. Revised 10/28/2026.
“From the moment the remains arrive at the institute, identification is conducted through three methods: dental records, CT scans, and DNA testing.
“Even if we identify the remains using one method, it’s not enough until we have definitive identification. In most cases, whenever possible, we perform all three methods to get a final result.” According to Kugel, this is because the “findings” often arrive in an unorganized manner, and no one knows to whom they belong.”
Oh, and there’s one additional complication. Some of the bodies died as long as two years ago. Some of these remains were returned from Gaza after the latest cease fire. I don’t know how many of these people died after October 7, 2023, but it’s possible that some of them may have.
“It’s important to understand that our daily work is to examine bodies that arrive within hours or a few days in rare cases. Here, we’re dealing with a two-year period, and that makes a significant difference in how the remains were preserved, under what conditions, and how that affects the identification process.”
But they aren’t just identifying Israelis.
“Identifying former Hamas leader Yahya Sinwar was a defining moment for Kugel.
“‘Once you’re with the body and examining it, you don’t think at that moment that you’re examining someone very significant. We also had to understand what caused his death. Obviously, he had a head injury, but we tried to understand what preceded what.’
“When we finished, a colleague said to me: ‘Do you understand who you’ve examined now? The man who is responsible for the massacre of thousands of people.’ You don’t think about it while working, just as with the good people who were killed in the war, you just check and identify. After that, at home, you continue to read about him and his family; it goes with you, and then you process what you go through at the institute.”
This is a common challenge in forensics. Identification of a particular person may result in a number of emotional responses, whether it is a criminal or a victim. But the forensic professional’s job is to simply examine the evidence. The grief comes later.
If you missed my May writings, the friction ridges on fingerprints, palm prints, and elsewhere are used for everything from solving crimes to protecting smartphones.
If your biometric company offers a product that harnesses the power of friction ridges to identify people…do your prospects know about how your solution benefits them?
If your company employs biometrics to identify people rather than to monitor their health readings, then you don’t care about the Orlando where visitors wear hats with mouse ears.
Because many of the subscribers and followers of my Substack page aren’t fingerprint experts (although a few are), my posts on Substack tend to be more introductory. So I wrote this for Substack, but also decided to share it on the Bredemarket blog at some point.
If you look sort of closely at your fingertip, you see one commonality between (most) fingers and Ruffles: both have ridges. For purposes of this exercise, take a close look at where the ridges go.
In some cases, the ridges just stop and go no further.
In other cases, a single ridge splits into two or more ridges. Or if you want to follow a different perspective, two or more ridges combine into a single ridge. But that perspective screws up the discussion later.
Ridges do other things which I will ignore for now.
The important things is that you can identify the specific point at which a ridge ending occurs. And you can identify the specific point of a bifurcation, where a ridge splits into two ridges. (If a ridge splits into three, that’s a trifurcation.)
Those ridge ending and bifurcation points? Those are the minutiae.
Human fingerprint examiners can identify these minutiae points.
So can the algorithms on an automated fingerprint identification system (AFIS) or an automated biometric identification system (ABIS).
And if two fingers have minutiae in the same locations, and don’t have minutiae in one finger that are not present on the other finger…then they’re the same finger. (I’m simplifying here, since the quality of the prints and the way the skin bends affect the ability to find minutiae.)
Which means that if the police find a fingerprint on a stolen car that doesn’t belong to the owner…
…and the minutiae on your finger match the minutiae on the print from the car…
…you’d better have a good lawyer.
Oh, and one more thing: you also have ridges, ridge endings, and bifurcations on your palms and toes. So don’t try to steal a car while barefoot.
…how the fragmented, decentralized nature of American law enforcement and forensic practice creates a landscape where what counts as science (and possibly what counts as justice) can vary wildly depending on where you happen to be.
There are about 18,000 police agencies in the United States at all levels of government, and 400 separate forensic laboratories.
But we have standards, right?
Do Even when national scientific bodies like ASTM or NIST’s OSAC develop well-reasoned, consensus-based forensic standards, adoption is purely voluntary. Some laboratories fully integrate these standards, using them to validate methods, structure protocols, and train staff. Most others ignore them, modify them, or apply them selectively based on local preference or operational convenience. There is no enforcement mechanism, no unified system of oversight. The science exists, but whether it is followed depends on where you are.
Houck’s article details many other issues that plague forensic science, but the main issues arise because there are 18,000 different authorities on the matter. Because this is a structural issue, deeply rooted in how Americans think of governing ourselves, Houck doesn’t see an easy solution.
Reforming this system will not be easy. It runs up against the powerful American instincts toward local control, political independence, and legal precedent. Federal mandates for forensic accreditation, national licensing of analysts, or the establishment of an independent forensic science* oversight body (all ideas floated over the years) face stiff political and logistical resistance. I don’t give these ideas much of a chance.
Even Houck’s minimal suggestions for reform are questionable. In fact, if you read the list of his solutions at the bottom of his article, you’ll see that he’s already crossed one of them out.
Federal funding could be tied to meaningful accreditation and quality assurance requirements.
