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Scanning the retina, detecting pollen particles on clothes or even smells – there is practically nothing to hide from the latest forensics. Trends have collected methods that used to work only in science fiction films
DNA is the Queen of Evidence
In 1989, in Las Vegas (USA), next to the school path, the body of 14-year-old Stephanie Isaacson was found. She was attacked, abused and strangled. The killer was not found then. The investigation had no evidence, only traces of sperm on the T-shirt that the girl was wearing at the time of the murder. 30 years ago, this was not enough to figure out the criminal.
Everything has changed in the XNUMXst century. At firstFor DNA analysis, scientists have learned to use a high-precision method of molecular genetic diagnostics – polymerase chain reaction (PCR). In a landmark moment in the history of DNA profiling, forensic scientists can now work with less biological evidence.
Previously, in order to obtain DNA, a stain of blood or other biological fluid had to be the size of a coin. For the latest forensics, evidence can be the smallest trace of material that contains fragments of tissue or cells: saliva, urine, feces, hair, teeth or bones.
Secondly, DNA bases continue to accumulate, including private ones. In the USA, for example, genetic tests are popular, which are used to compile the genetic tree of a kind. If a relative of the suspect is in such a database, law enforcement agencies will see the matches and identify the identity of the potential offender.
This is how the murder of Stephanie Isaacson was solved in 2021. From the traces of the seed left on the girl’s clothes, DNA was isolated, and only 0,12 nanograms or 15 cells of biological material were available for analysis. With the help of public genealogy data, the suspect’s cousin was identified, and through him the killer was also identified. It turned out that he died in 1995.
Today, forensic scientists can extract DNA from even a few skin cells left after a person has touched an object or victim. In the United States, murders that have been “hanging” since the early 1990s were revealed in this way: in the north of the city of Phoenix, not far from the Arizona Canal, the bodies of raped girls were found. The material was then carefully collected, there were also suspects, but nothing could be proved.
Nearly 30 years later, undercover cops conducted an operation: they invited suspect Brian Patrick Miller to a restaurant, and then his mug was submitted for examination. DNA from the mug was compared with DNA from the scene. The coincidence eliminated all doubts: this is the same criminal who has been looking for for many years. Miller has been waiting for trial for six years, his lawyers are delaying the process, meetings are constantly postponed. The man faces the death penalty.
Three-dimensional technologies in forensics
3D laser scanning is capable of presenting the crime scene to the court in all its details. Unlike traditional measurements, when a criminalist measures everything with a tape and a ruler, the scanner eliminates even the smallest inaccuracy, fixing all distances, angles, areas, volumes. Each piece of evidence has an exact coordinate.
In addition, the standard description of the scene is not a quick task. 3D laser scanning will significantly reduce it: in the event of a small accident, the use of the scanner takes no more than 15 minutes, and 10 of them are its settings. The highway will quickly unload, and the police will not take risks once again, fixing the details of the accident.
Another 3D technology promises to be an ultra-precise tool for identifying suspects. Researchers from the universities of Nottingham and Kingston (UK) have learned how to create a three-dimensional model based on a single photograph. As a rule, a three-dimensional reconstruction requires several images from different angles and it is desirable that the face does not change expression, does not distort in grimaces.
However, the new software recreates it in 3D even if some part is not visible in the picture, for example, the eyes are hidden behind sunglasses. This will not interfere with the recognition algorithm: the computer will compare the image with hundreds of thousands of faces in the database and give the correct result.
Until recently, 2D technology was used to recognize criminals; in all forensic databases, images of criminals are two-dimensional (flat).
Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
A mass spectrometer is a special scale for weighing molecules: if a specialist knows their weight, he will understand what kind of compound (substance) is in front of him. Such a device will detect traces of a chemical compound, even if only a few molecules remain of it.
For example, he will “see” whether a person has dealt with any dangerous substances: he will “calculate” this by an invisible trace on his hands or clothes. In essence, a mass spectrometer is a precision electromagnetic balance on which atoms can be “weighed” with an accuracy of 10−31 grams.
Inductively coupled plasma mass spectrometry is a highly sensitive technology. Inductively coupled plasma acts here as a source of ions. If glass was broken during the crime, ICP-MS will study the remains, destroying them almost to the atoms. The glass from the scene will then be compared with a tiny piece on the suspect’s clothing or car to prove with absolute certainty that they are the same material, i.e. not just abstract glass, but its fragment from the scene.
Witness car
In the summer of 2017, the body of auto mechanic Ronald French, who was searched for three weeks, was found in a cornfield in Michigan (USA). He was tied with a cord to a car and dragged across the field until he died. The crime remained unsolved until in 2020, one of the detectives decided to try a new method – digital forensics of vehicles.
Experts extracted and studied all the data from the on-board computer of a black Chevy Silverado pickup truck stolen on the day the owner disappeared. It turned out that the car had saved tapes with timestamps, which showed the voice of a man ordering the car stereo to turn on rapper Eminem. The timing of the voice command and French’s murder coincided.
The voice belonged to a colleague of the slain auto mechanic, 30-year-old Joshua Wessel. His relatives, including his wife, recognized him from the record. Wessel pleaded not guilty and is now awaiting trial.
Modern cars, especially the latest models, are smartphones on wheels. All of them have a computer “brain”: a navigator, a video recorder, Bluetooth, through which the driver and passengers can connect their phones. A person registers a smartphone in the system, and the car gets access to call logs, contact lists, messages, emails, photos, videos, applications, he knows the sites that the owner has visited.
The car system can tell where and when the car was heading, whether the driver and passengers were seated, where the doors were opened, whether the lights were on, whether the trunk was used, whether they accelerated or braked hard. All this data can be used by forensics in the investigation of accidents, thefts, etc.
Virtual autopsy
With a real autopsy, he has only one thing in common – the expert will see everything that happens inside the body. You don’t have to cut for this: this is almost the same study that is performed on ordinary patients.
A virtual autopsy (virtopsia) is an alternative to the traditional method, which many religiously, for example, as in Chechnya, have a bad attitude towards. The corpse is scanned using 3D photogrammetry, then passed through a CT scanner that takes 3 x-rays from head to toe. After combining MRI and CT with 500D computer reconstruction, a 3D image of the body is obtained.
Virtual autopsies can be performed over the Internet. After that, there will be a record that you can show colleagues and get their opinion. Or, for example, to present in the courtroom: a three-dimensional or interactive image, firstly, is devoid of naturalistic details, and secondly, it is much more convenient to explain the technical nuances of what happened using its example.
The results of virtual autopsies are recognized by Swiss courts, used by Australian criminologists, and since 2004, the body of every dead soldier has been sent to the US Army for X-rays and CT scans.
Unlike the traditional method, virtopsy allows the forensic specialist to see the exact location of the foreign material. For example, investigators were unable to locate the bullet exit hole when a 50-year-old man shot his wife in the back of the head with a pistol. On the XNUMXD image, the pathologist saw that the bullet had passed through the brain at a right angle and lodged in the spinal canal, which is rarely tested in a real autopsy.
In Switzerland, the authenticity of virtopsia was specially checked. At the Institute for Diagnostic Radiology at the University Medical Center in Bern, about 100 times, the bodies were first examined virtually, and then a traditional autopsy was performed. The results were almost identical.
More and more ordinary people trust the results of a non-invasive autopsy. In the US, it is gradually becoming a regular paid service. For $2, anyone can order their own posthumous virtopsia, which eliminates possible disputes over inheritance. And it also acts as a kind of guarantee that none of the relatives will encroach on the life of the customer.
Virtopsia significantly saves the working time of a forensic expert: a full MRI examination takes no more than half an hour, while a classic sectional autopsy takes several times longer. You won’t need as many refrigerators to store the bodies, which can be issued for burial immediately after the research. In the event of new circumstances, exhumation is also not needed.
Despite the obvious advantages, in order to become a common practice, the virtual autopsy procedure must overcome many barriers related to logistics, staff training, and cost. The price of one MRI machine can reach up to ₽100 million, CT – up to ₽50 million. Large clinics have them, but they are used to diagnose living people, patients. To reconfigure the system to serve a different category of customers, you need the desire and time.
Forensic phenotyping
This method, which appeared already in the XNUMXst century, makes it possible to predict the color of a suspect’s hair and eyes based on a variety of DNA markers. Susan Walsh and Manfred Kaiser were among the first to develop phenotyping technology. They developed the HIrisPlex method, which made it possible to determine the color of a person’s eyes. Then it was expanded with additional genes, which can be used to recognize the color of the skin and hair. Now the site is fully automated: by uploading genetic information there, you can get a minimal description of the appearance.
There are already developments in this area using artificial intelligence: geneticist Craig Venter introduced the Human Longevity system in 2017, which is trained on the genetic data and appearance of more than a thousand volunteers. This AI is able to predict not only the color of eyes and hair, but also to draw conclusions about age, weight, height and other characteristics of appearance. Venter claims that the effectiveness of his program is about 74%, and you can determine the appearance of a person by just one fingerprint.
With the help of phenotyping, several cases have already been solved: for example, in 2012 in North Carolina they managed to catch a criminal who committed a double murder. The masked perpetrator killed Whitley French’s parents and fled, leaving a few drops of blood on the floor. It was they who made it possible to conduct a DNA analysis and determine that the killer was dark-haired and fair-skinned and had a European-Hispanic origin. Armed with this data, the detectives turned their attention to Whitley’s fiancé’s family, and found a match between his brother’s DNA and the killer’s DNA samples. Thus, forensic phenotyping helps narrow down the suspects.
Recently, forensic phenotyping was used to reconstruct the appearance of three Egyptian mummies. The samples the scientists worked with are from 2023 to 2797 years old. With the help of DNA analysis, it was possible to determine the origin of men, the color of their eyes, hair and skin.
Phenotyping is only a developing branch of forensic analysis, and therefore many scientists criticize it. First, many of the methods were based on European data, so they may not work as well with people of other races. Secondly, our appearance depends not only on individual genes, but also on the intricate interaction of entire systems of genes, as well as on various external factors: age, environment and lifestyle.
Morphometry
Anthropologists from the University of North Carolina have come to the conclusion that morphometry – the measurement of body parts – can help in cases of missing children. Most morphometric methods are based on the analysis of two-dimensional or three-dimensional coordinates of anatomical points, from which any distance or angle defined by these points can be calculated. Often the key step in solving a crime is the identification of skeletal remains, but in cases involving the remains of children, traditional methods do not always work. Previously, it was believed that only people over 18 years of age could determine the origin of a person using skull analysis. Scientists have found that the face acquires specific features for about 14 years. For example, Professor Ann Ross, one of the authors of the study, was able to use these findings to study the remains of an unidentified 10-year-old boy found in 1998 and determine that he was of Central American origin.
Ross has created a technology called 3D-ID that helps identify the origin of unidentified skulls. Using geometric morphometry and a graphics tablet with a pen, the anthropologist records up to 34 skull coordinates and compares these measurements with other skulls in the database. The software makes specific inferences: not just “Hispanic,” for example, but “Central American Hispanic” or “Caribbean Hispanic.”
Pollen biomarkers
Palynology, or the study of pollen and spores, is a promising discipline in forensic science. Pollen is a biomarker that can be used to determine the time and place of a crime, since flowering plants are almost everywhere, including caves and deserts, and flowering is always tied to a certain time. Thanks to the cell wall made of cellulose and sporopollenin, pollen particles are resistant to decomposition, which means they can help solve a crime even after many years. Palynology can help in the search for missing persons or in drawing up the route of a criminal.
Although pollen analysis has been used to solve criminal cases since the 1960s, it has never been widely adopted. This is due to the fact that there are not so many competent palynologists. Nevertheless, examples can be found: for example, in 2005 in New Zealand, detectives were able to bring charges against two robbers thanks to the St. John’s wort bush. One of the robbers was brought in as a suspect, but all the evidence was circumstantial and the man did not confess. On his clothes they found an accumulation of pollen from St. John’s wort, which grew in the garden of the house. This allowed the experts to conclude that the pollen did not appear by accident, but as a result of direct close contact with a flowering bush.
One of the few American institutions with a palynology laboratory is Texas A&M University. The laboratory was headed by Professor Vaughn Bryant. Bryant has been working for the government since 2006, dealing with illegal drug import cases. He trained the first full-time forensic palynologist Andrew Lawrence, who was hired in 2011 while still in graduate school. Sarah Ferguson joined in 2015.
There are about 380 different types of pollen grains, and the challenge for palynologists is to analyze these grains using microscopes. Lawrence and Ferguson have a reference library of 6 pollen species with access to 30 additional samples at the Field Museum of Natural History in Illinois. But their work is still not enough to cover all the needs of modern criminology.