Tag Archives: IAI

Points of Similarity in Ballistics and Fingerprints: So What?

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.

He also created the tripartite rule in 1914 for minutiae comparisons. David Doglietto summarizes it as follows:

“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.”

But the IAI’s determination had no effect on the laws in various countries. French and Italian courts require 16 matching points or the evidence is inadmissible.

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.

Nevertheless, consecutive matching striae is a thing.

Consecutive matching striae. From FIU.
Consecutive matching striae. From FIU.

“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.

But new methods are emerging.

“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.”

Why “Cheers” is an Anachronism

Privacy?

Let’s travel back to 1969 to the Beacon Hill neighborhood in Boston, Massachusetts. In that year and place, a bar started with the name the Bull & Finch Pub. It was popular with the locals, so much so that in 1982 the Bull & Finch Pub was named the “Best Neighborhood Bar” by Boston Magazine.

But something else happened in 1982 that would change the Bull & Finch Pub forever.

Charleses in charge

It turns out that Glen Charles, Les Charles, and James Burrows, the producers of a television show in development, needed an authentic setting and ended up in Boston scouting out locations (we’ll return to that).

“After visiting other Boston bars, they returned to the Bull & Finch and declared, ‘This is the place.’ An American television classic was born, and they would name it Cheers. The TV show premiered on September 30, 1982, and remains one of America’s most beloved situation comedies of all time.”

After the show ended, life imitated art and the Bull & Finch Pub was renamed Cheers Beacon Hill. That was the name it bore when I visited Boston in July 2006 for that year’s International Association for Identification conference.

From Facebook.

But I’m not going to talk about that.

I’m going to talk about the song.

Where everybody knows your name

TV shows need to have theme songs, and “Cheers” was no exception. Charles, Charles, and Burrows turned to a New York songwriting team, Gary Portnoy and Judy Hart-Angelo (known for “People Like Us” for the musical Preppies). After several attempts, the duo came up with a song, and Portnoy recorded the vocal demo to guide whatever big-name singer the producers selected to perform the real song. The producers selected…Gary Portnoy.

So for 11 years (and afterwards in syndication) we heard Portnoy’s voice at the beginning of every episode.

The name of the song?

“Where Everybody Knows Your Name.”

“Cheers” season 1 intro.

Say what?

When you read that song title, remember two things;

  • The song was written in 1982, not 2006 or 2026. Today, if someone says “when everybody know your name,” we immediately think of the surveillance state where everybody knows you name, your mother’s maiden name, and the name of your favorite pet.
  • The show was nostalgic, drawing upon the 19th century style illustrations in the show intro (even though the inspiring bar was founded in 1969). The neighborhood feel reminded us of a small community where everybody DID know your name.
Norm!

Was society like this in 1982? Not really. We had spent decades in the anonymity of big cities where we often didn’t know our neighbors.

And the surveillance state we face today was already in existence in 1982. The same band that wrote a song about Bob and Judy “scouting out locations” wrote another song (“Life During Wartine”) with the line “we’re tapping phone lines.”

We know that that ain’t allowed. (4:06)

So even in 1982, “Cheers” and its theme song were a fictional anachronism divorced from reality. The only reason that everybody knew our names was because our privacy had long since been compromised.

And one more thing; THIS song is NOT the one from “Preppies.”

John Goodman in “True Stories.”

And Virgil, Texas is another fictional anachronism, giving Talking Heads a hat trick (cowboy hat) in this post.

When IAI Attendees Say “Orlando” to Their Biometric Hungry People

There are times when the same word will have vastly different meanings to different people.

Such as biometrics and biometrics.

And Orlando and Orlando.

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.

You care about the Orlando where forensic professionals are gathered this week for the 2025 International Association for Identification Forensic Educational Conference.

Find the people hungry for your services by seeing who is paying attention to the #IAIConference hashtag on your favorite social channels.

These are the ones who will salivate over things like “Appendix F.”

This is your niche.

Speak to them.

And if you need assistance with content services to address your hungry people, Bredemarket can help.

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