"How much do you think one person is ready to kill another for today?" An excerpt from the book of a forensic expert

What is identification

There are people similar, there are doubles, identical twins are born. And yet there are differences between them. Let them be tiny, even at the level of one segment in the DNA chain, in the form of a barely noticeable mole on the back or the distance between the front teeth, but there is. In addition to ballistics, analysis of drugs and poisons, photographs and other technical things, forensic science deals with two of the most important problems:

By binding a person to a certain object, place and, if you're lucky, time.
Personal identification, that is, comparing one person with another or many. In professional language, it sounds like this: one to one or one to many.

So what is unique about each individual person? Fingerprints, you say, and DNA. That's right, that's what comes to mind first. Some of you, I'm sure, will point to the iris and the retina. And they will be right too. Did you know that the structure of a person's teeth, ear and lips is also unique?

It doesn't cost anything to do a little experiment. Color your lips with lipstick and blot them with a white paper towel. Ask a colleague to do the same. Make sure there is a difference. Just do not go out with such lips as a couple on the streets of your hometown. You may be misunderstood. Naturally, this advice does not apply to women.

With the ear, everything is a little more complicated. You don't need to paint it, just take a large picture of the ears of several of your friends and compare the photos.

If it is necessary to identify a living person, identification is applied by:

fingerprints and palm prints;
iris and retina of the eye;
voice;
the structure of the face;
gait;
the location of the veins in the area of the hands;
handwriting;
the structure of the teeth;
ear;
lips.

But in other circumstances it is necessary to identify the corpse. When we deal with a dead body, we investigate:

fingerprints and palm prints, if any;
DNA, the sources of which are blood, saliva, sperm, hair with roots, skin, skeletal system;
the structure of the teeth, if the oral cavity is somehow preserved.

It should be noted here that the fingerprints and palms of the corpse are not always preserved in a state suitable for the comparison procedure. A corpse can burn, lie in water for a long time, in a closed car, or simply decompose. But DNA can withstand the test of time, fire, water, and explosion. As for the structure of the teeth, this is a very difficult procedure, since for comparison you need to have panoramic images of a person taken during life.

The identification of the living is a confusing question from a theoretical point of view, although the process itself is more or less worked out. The fact is that professionals still argue about which of the identification methods are perfect, and which have errors and, therefore, can lead to incorrect results.

It is generally accepted that fingerprinting is infallible. We will also accept this postulate for now, although it is very shaky. To the question "Why?" I will answer later. DNA analysis is extremely reliable, since it, like any self-respecting scientific method, is based on statistical data.

The category of absolute includes identification by the iris and retina of the eye, the geometry of the veins, the structure of the ear and the shape of the lips.

These methods are very difficult technically, therefore they are not always applied. However, the uniqueness of the iris and retina, the geometry of the veins are increasingly used in biometric access systems. But the ear and lips were "unlucky", they are practically forgotten. Identification of people by gait is a fairly young area, and it is difficult to say how it will take root in the future.

Today, a separate discipline is also involved in identification issues - biometrics, based on the measurement and analysis of physiological, anatomical or behavioral characteristics of a person. It was born at the intersection of physiology, physics and computer technology and unusually quickly developed into a super-demanded field of science and industry with billions of dollars in annual turnover. Firms that develop and sell biometric systems claim their products are perfect. Indeed, every year it becomes more accurate and easier to use due to advanced software, smart, self-learning computer programs and more sensitive sensors.

There are several criteria for assessing the accuracy of biometric recognition systems, the main ones of which are:

false positive identification;
false negative identification.

In the first case, the system recognized the wrong person, and in the second, it did not recognize the right one. Can you imagine a situation where the biometric control of access to the command bunker does not recognize the chief of general staff? Why is there the General Staff, a person cannot get home, because instead of the usual door key, he went broke on an expensive biometric system. The less false positive and false negative, the more reliable the system.

The more serious (and, accordingly, more expensive) the biometric system, the more verification elements it includes. Good models often use fingerprinting, iris analysis, and in addition voice or facial structure. The US Marines in Afghanistan and Iraq have long been equipped with a device that looks like a regular camera. The camera has a database of irises of persons previously arrested on suspicion of terrorism. When meeting with a suspect, the soldier requires him to raise his hands and look into the camera's peephole. The comparison is carried out instantly. Israeli police have a similar miniature fingerprint comparison system. The memory of the device stores tens of thousands of "embedded" fingerprints, and in case of a negative search result, it sends a request to the main national database, the answer to which comes immediately.

It is no coincidence that we left for last identification based on voice recognition and handwriting comparison. Both have a long history and are widely used.

You, of course, have read Solzhenitsyn's The First Circle? In the Stalinist “sharashka”, prison scientists are developing a voice recognition system. Today it is a large and actively developing area, about which you can write a separate book. The primitive graphics from Solzhenitsyn's novel are deep in the past. Voice recognition has become just a part of the interdisciplinary science of speech recognition, which includes many areas of physiology, psychology, linguistics, computer science and signal processing. Each of us can touch the simplest edge of speech recognition problems by turning on the speech to write function on our smartphone.

Very few countries have voice recognition departments in their forensic services. There are two reasons for this. Voice identification is still not accurate enough due to the fact that a person's voice is highly dependent on his age, emotional state, health, hormonal levels and a number of other factors. The second reason is that most services prefer to invest money and funds in highly accurate and proven areas - DNA analysis and fingerprinting.

Comparing handwritings is a delicate matter; it takes several years to learn this specialty. The identification is carried out, as a rule, according to the method "one sample against another" (one to one). Well, for example, a suicide note was found near the body hanging in a noose: "I ask you not to blame anyone for my death." Did the person write himself or did someone do it for him? A note and samples of the victim's handwriting are delivered from his home to the forensic laboratory. Notebooks, shopping lists, notes. The specialist compares the spelling of the corresponding letters, tilt, pressure, typical curls, distances.

Of course, there is a possibility of errors, because handwriting depends on many parameters: the state of mind of a person, the surface on which he writes, the substrate, lighting, such as a pencil or pen, and the purpose of writing. Did you write a memo for yourself? Guidance to children? Complaints to a friend?

Ignorant people often confuse the comparison of handwriting with graphology. The first is science, and the second is profanity, because it claims to recognize the character of a person.

Here the pressure means aggressive, but here the density of the letters is high - it means, miser, well, further in the same spirit. The saddest thing is that the graphologists managed to stand on their feet and stand firmly on them. They have their own associations, presidents, congresses, magazines and, most importantly, clientele. Millions of people allow themselves to be fooled and pay for it. A scientific seminar has been working in our department for decades, the coordinator of which I was at different periods of my service. In 1997, I invited two famous graphologists to speak at it. Our experts from the document verification laboratory almost tore them to pieces right on stage.

About cunning lawyers and unscrupulous experts

How much do you think one person is ready to kill another for today? I have no opinion on this matter, but there are facts, and you will find them if you read this chapter to the end.

Two very middle-aged men had a small common business in Tel Aviv. At some point, a disagreement arose between them, and Ronen Mor killed Avi Kogan with a shot in the head from a revolver. He loaded the body into a red Fiat Fiorino and took it to a vacant lot near new buildings in the north of the city.

Nothing original. In an even simpler way, Ronen decided to get rid of the car: he paid the tow truck and asked him to drive Fiat to the parking lot of a nearby shopping center.

A day after the murder, workers, taking out the remnants of fittings from the construction site, stumbled upon a corpse. Mor, as the only business partner, was interrogated and detained because his behavior during the initial conversation did not inspire confidence in the investigators. The car was found quickly and already at the first superficial examination we noticed traces of hands in blood on both rear doors. A laboratory examination established that the blood belongs to the murdered, and the traces belong to the murderer. "So what's interesting?" - you ask. Please be patient, we are just beginning the story.

Ronen Mohr, who was arrested on murder charges, met with his lawyer, and together they wrote a wonderful script:

Ronen Mohr is ill, has Alzheimer's and has blackouts.
He is an elderly man, he sees poorly, especially at night.
Naturally, he did not kill Avi Kogan.
Two strangers, very serious-looking men asked him for a car for a short time, and out of fear he agreed.
They returned the car to the office late in the evening, when it was already dark outside.
It was at this time that Mor was coming out of the closet, where he washed his hands, and, possibly, touched the door of the car with his damp palms.
Since Mor can hardly see in the dark, he did not notice dried blood stains on the red car.
Having touched such a stain, he left his prints in the blood on the clean spot of the car body.

It was clear to everyone that of the eight points in this exciting story, at least the last five were nothing more than impudent delirium. But the lawyer went even further: he ordered a private forensic expert, a former employee of our department, an examination, which would prove that if you touch a dry blood stain with a wet hand, you can leave a fingerprint in the blood on the clean surface of the car body. And the expert gave such a conclusion! True, he lost his conscience only partially, since he wrote a conclusion that was only two lines long:

"It is impossible to exclude the possibility of transferring a print from a dry blood spot to a clean surface when touching the spot with a damp hand."

The expert did not bother himself with the experiment.

With this examination in hand, two prosecutors came to the laboratory: “What are we going to do? It is clear that this is nonsense, but the judges will demand an official opinion from the police, so write a response."

To give an expert opinion, it was necessary to conduct an experiment, and this required:

10 metal samples of the 1997 Fiat Fiorino body, not red, but white, to achieve better contrast on the surface. The police, rolling in millions, struggled to find the money to pay for the garage, which had agreed to cooperate. The garage would have already given samples to help the police, but only by law you cannot take anything from anyone without paying and receiving a receipt.
Six volunteers willing to participate in the experiment Why 10 metal samples and six volunteers? So that in the end the results of the experiment at least somehow meet the requirements of statistics. …
50 milliliters of blood from each of the six participants (for hygiene reasons, people should only come into contact with their own blood).

The task before us was simple only at first glance. First of all, it was necessary to define what “wet hands” are, because this is not a scientific concept. This means that a so-called step-by-step experiment was required, during which it was necessary to intuitively change the humidity of the hands from completely dry to completely wet. And so they did: smeared their blood on white metal surfaces lined with squares; samples were dried at a certain temperature for a fixed time; with a moistened finger, the employee alternately touched a dry blood stain and a clean area of metal.

And so on until in a clean cell it was not possible to see at least something that looked like a fingerprint in the blood. If this effect could be achieved, then both the original spot and the print were photographed. Of many hundreds of experiments, a positive effect was recorded only in a few cases, when the employee's hand was completely wet, and the contact with the stain was especially dense and long-lasting. By zooming in on the blood stains, we saw an interesting feature.

Whenever it was possible to leave an imprint, traces of the papillary pattern of the pressed finger were visible on the original blood stain. On the stains of dried blood on the Fiat doors, this effect was not noticed!

Ronen Mohr was convicted of first-degree murder by a district court and received a life sentence. At the trial, his lawyer questioned me for two days for four hours about the actions that I described to you in a hundred lines. A year after the end of the trial, the lawyer died of cancer, and Mor about the same time - in prison from a heart attack.

Yes, I almost forgot: the dispute between partners came out over four thousand dollars.

Boris Geller is one of Israel's leading forensic experts, an expert in fingerprinting and crime scene investigation. He generously shares his knowledge, recalls cases from his own practice, talks about the history of the formation of forensic science and its state in many countries of the world, including Russia.

Geller's book "The Science of Crime Detection" will be of interest to the widest circle of readers - from fans of action-packed detective stories to those who are seriously interested in crime investigation and law enforcement.