1, strictly confidential, confidential for the parties.
2, do not accept bribes, justice is more important than money.
Don't pity your bones and muscles even if the search is fruitless.
4. Don't make preconceived judgments. Only conclusive evidence is a fact.
5. Don't write inaccurate investigation report.
6, don't be moved by personal feelings, reason is better than emotion when acting.
7. Self-defense techniques such as judo and karate should be mastered.
8. Knowledge of psychology, forensic medicine and forensic medicine is also essential.
9, keen observation. And can scientifically observe the meteorological conditions at the time of the crime, as well as the special situation at the scene, because some evidence will disappear and change with time.
10, with direct perception, see through the truth through an inconspicuous material evidence.
1 1, relying on rich imagination, reasoning and reproducing various means of committing crimes.
Tracking technology:
1, don't hesitate for fear of being discovered by the other party, but act cautiously and decisively.
2. If the other party is hiding in the building, it is necessary to quickly find out whether there is a back door and an escape route.
If you stare at the front blindly, you may be followed by your partner, so you should always pay attention to the front, back and forth, left and right.
4. Prepare simple makeup tools in advance.
It's necessary to prepare biscuits, chocolates and other carry-on foods.
6. When you have time, hurry up and keep it light at any time.
7. When stalking women, be careful not to be mistaken for hooligans.
8. Wear silent rubber shoes.
9. When the other party buys a ticket, boldly approach and find out where to go.
Monitoring:
1, carefully investigate the surrounding terrain and hide in places where prisoners are easy to escape.
To prevent domestic dogs and wild dogs from growling, dog food should be prepared.
3. Even if you stay in one place for a long time, you should dress up to avoid being suspected. For example, at the seaside, you should dress up as a fisherman; Dress up as a couple or a sketch artist in the park.
If you stay in one place for a long time, it will be difficult to move quickly once something happens, so you should always exercise your hands and feet and relax your muscles.
When hiding in the car, it is best to change the position of the car frequently.
6. When two people lie in ambush separately, if you need to contact with the walkie-talkie, you should contact the dog or cat.
7. In order to prevent mosquitoes in summer, prepare pesticides.
8. You can bring a miniature camera to record the location and time of the tracked person.
Asking:
1, if you want to gain the trust of the other party, you should first speak politely.
2. Listening is better than speaking.
If the other person has a pet at home, let him play. In this way, the other party will talk to you harmoniously.
The important things should be asked again from different angles before they can be confirmed.
5, don't record in front of the speaker, so as not to cause the other party's vigilance, so write down what you hear in your mind.
6. If you are really afraid of forgetting, you should train your hands to take notes in your pockets.
7. Pay attention to each other's complaints and chats.
8, according to each other's speaking habits, change the way of speaking at any time.
tooth
Teeth are also important clues to solve crimes. Doctors can infer sex, blood type and age from a tooth.
It is not difficult to determine the blood type. This is because the medullary cavity contains blood group substances. During the examination, the crown of the tooth is cut off, the tooth is put into distilled water, then the anode platinum wire is inserted into the root canal of the tooth, and the cathode is put into the external liquid. After electrifying for 2 minutes, distilled water turns yellow-brown, which can be used to determine blood type.
As for sex determination, it is tested by chromosomes: in the nucleus of human cells (including white blood cells), the 23rd chromosome is sex.
Chromosome. The male is XY and the female is XX. When testing, mainly check the Y chromatin. If there is y, it is male; No, it's for women. number
Sex can be determined only by dyeing dental pulp cells in the dental pulp cavity, and men and women can be distinguished by a drop of blood and a little somatic cells.
How can you tell your age from a tooth?
The older a person is, the easier it is for his teeth to wear out. Doctors can roughly judge the age of the deceased according to the degree of tooth wear.
Age:
Tooth tip began to wear, about 13 ~ 23 years old.
Tooth tip is worn, revealing black spots (tooth particles), about 24 ~ 35 years old.
A large area of exposed dentin, about 36 ~ 55 years old.
Dentin is completely exposed, and the tooth cavity can be seen, probably over 56 years old.
If there are many teeth, you can also judge the age from the growth of teeth. For example, deciduous teeth are usually about 6 months long, and when they are 2 years old.
At the age of 20. At the age of 7-8, the teeth began to change, and the left and right upper and lower first molars began to grow. 1 1 year old, all deciduous teeth were replaced by permanent teeth.
/kloc-Before the age of 0/6, the second molar will grow. At the age of 25, the third molar (wisdom tooth) will grow out. '
The dead with dentures and metal braces have obvious characteristics, and doctors often use these special teeth to identify the dead.
who is it? For example, in May of 1978, a skeleton was found in a cave in Guizhou, and it was found that the first and second canine teeth of the upper jaw were inlaid with silver and copper.
Teeth. Public security investigators extensively investigated the tooth characteristics of the missing persons over the years and found that the missing young women of a production team were cheated into going up the mountain.
Killed, the murderer received the punishment he deserved.
In addition, in the fight, the victim is often bitten by the murderer, leaving teeth marks on his body, which can also be used as a clue to solve the case.
Once, according to the bite marks on the victim's body, a doctor judged that he had a long oval face and a small chin, and was about 20 years old. According to this,
Judging, it did solve the case and caught the murderer in one fell swoop.
After the plane crash, the deceased was covered in blood and could not recognize his face, and his teeth were often used to judge the identity of the deceased, for example, according to his death.
Information or dental records of dental implants, fillings and dentures provided by the family members of the deceased, or blood type, sex and age determined according to the teeth of the deceased, can be used.
Provide a basis for identifying the deceased.
On the way to the Soviet Union, Lin Biao's Trident plane crashed in Delmer County near Windur Khan.
All nine people on board were shattered. Because Lin Biao had recuperated in the Soviet Union, had treated dental diseases and installed dentures in Moscow, the Soviet side mastered it.
Lin Biao's dental records. After investigation, the tooth features are consistent, which proves that it must be Lin Biao's body.
After the 9. 1 1 incident in the United States, many bodies were identified by examining their teeth, which is accurate and simple.
There are also parts of the body that have been burned and have been deformed and deteriorated, which is difficult to identify. Only the teeth are relatively complete.
Yes, doctors can accurately identify teeth by examining their characteristics.
Before committing suicide, Hitler, the chief culprit of World War II, ordered his men to wrap the body in a military blanket, carry it into the garden, and pour gasoline on it to burn it.
Because there was no way to identify the charred body at that time, the Soviet Red Army could not determine whether Hitler was dead or not. So Hitler
His death became an unsolved case in history.
It was not until 3 1 year later that a Norwegian expert confirmed that the charred body was indeed Hitler's body.
carbon monoxide
Carbon monoxide is inhaled through the respiratory tract. Inhaled CO enters the blood through alveoli, and immediately combines with hemoglobin to form carboxyhemoglobin (HbCO).
The higher the partial pressure of CO in the air, the higher the concentration of HbCO. Most of the absorbed carbon monoxide is discharged from the respiratory tract in a constant form.
At atmospheric pressure, the half-life of CO is 128 ~ 409 minutes, with an average of 320 minutes. After the contact is stopped, if the oxygen partial pressure of the inhaled gas increases, it can be reduced.
Carbon monoxide has a short half-life.
CO entering the blood forms reversible knots with hemoglobin and some other ferritins (such as myosin and cytochrome of ferrous iron).
It has a strong affinity with hemoglobin, that is, the affinity between carbon monoxide and hemoglobin is about 300 times greater than that between oxygen and hemoglobin, thus causing blood.
The oxygen carrying capacity decreases, and the dissociation rate of HbCO is 3600 times slower than that of oxygenated hemoglobin, and the existence of HbCO affects oxygenated blood.
The dissociation of hemoglobin hinders the release of oxygen, leading to hypoxemia and tissue hypoxia. The central nervous system is most sensitive to hypoxia, so
First of all, it is implicated. Hypoxia causes edema, increased intracranial pressure. At the same time, hypoxia and brain edema cause cerebral blood circulation disorder and vascular anastomosis.
The globus pallidus with imperfect vascular structure can appear white matter softening, necrosis or extensive demyelination, thus producing Parkinson's syndrome.
People generally become stiff within 30 minutes to 2 hours after death, and will become stiff after 9 to 12 hours. After 30 hours, it will continue to be stiff, then it will soften and return to its original state in about 70 hours. ※.
This is usually the case, but if the ambient temperature is higher than 35 degrees, the stiffness and softening will accelerate and recover after 24 hours. ※.
After strenuous exercise before death, protein will solidify easily in the body, and become stiff faster than usual after death. ※.
Suicide is when a gun is pointed at the head, which will leave hot marks around the bullet hole and the color of the surrounding skin will deepen. Besides, the hole the bullet enters is smaller than the hole it exits, and there is less blood flow. ※. Under normal circumstances, only suicide will leave burn marks.
If the lungs are perforated, even if you want to breathe, you can't breathe smoothly because the lungs can't expand, which will lead to suffocation and death. You can probably struggle painfully before you die 10~ 15 points. ※.
Drowning: slight water stains in the mouth, dilated pupils, bleeding on the mucous membrane of the eyes, and rupture of the eardrum due to water pressure, leading to bleeding. ※.
Poisoning: the lips turn purple or black first, and then other parts of the body will also appear this phenomenon. Sometimes eyes stare, hands clench fists, waist and legs curl up, etc. ※.
Choke to death: there is a deep purple imprint on the throat. When it hurts, the pupil expands and the tongue sometimes sticks out, showing purple-black. ※.
Cleaning the wound with tea to neutralize toxicity is the best way to deal with sea snake bites, because tannins contained in tea can detoxify. In addition, the person in charge of sucking out the poison should also gargle with tea to prevent poisoning. ※.
In case of food poisoning, mung beans can be ground and washed to temporarily remove toxicity. ※.
When salt is mixed with acidic detergent, it will produce toxic gas. ※.
The skin of the deceased was pink with some spots from the inside out, which was obviously caused by sodium hydroxide poisoning. If the poison be in the capsule. ※. It takes at least 15 minutes to show toxicity. It is best to gargle with something containing protein, such as milk.
Potassium cyanate is insoluble in cold water. ※.
The surgeon will leave a deep and obvious mark on his index finger, which is caused by frequent dressing. ※.
The hair of the deceased was slightly burnt and the muscles of the whole body were extremely stiff, which was the characteristic of high-voltage electric death. ※.
The scald caused by the current flowing into the body from the fingertips will turn the fingers gray. ※.
Eating potassium cyanate will suffocate and die (potassium cyanate has almond flavor). ※.
If you poison a flower, the flower itself should wither first. ※.
On the surface, it seems to be a "suicide" death by biting off the tongue, and sometimes it is a convulsion caused by inhaling poisonous gas or swallowing poison. ※.
There are many kinds of poisonous bacteria, some of which release poisonous toxins. Poisonous bacteria can also be used as medicine, but they are also poisonous, so you'd better not eat them. ※.
Carbon dioxide poisoning: the gas around people contains more than 20% carbon dioxide, so people will have severe convulsions after inhalation, and they will bite their tongues in a few seconds and die of cold. Carbon dioxide is heavier than air, so it will sink in a certain space. ※.
If the spasm is caused by massive bleeding, a rope must be tied around the wound to stop bleeding and prevent excessive bleeding. Next, massage your heart. ※.
If a person's internal organs are broken, there will be a special smell of internal organs. ※.
A big echo in the cave means there is no road, and a small echo means there is still a road. ※.
Sodium thiosulfate (bleach) can detoxify potassium hydroxide. ※.
The surface of pearl is composed of calcium carbonate, which is most afraid of acid corrosion. Therefore, when touching precious pearls, be sure to wear gloves or wrap them with handkerchiefs. If you don't use them, pearls will come into contact with oil stains on your hands, and the luster of pearls will disappear faster. The luster life of pearl surface is 30~40 years at most, and then it will fade slowly. ※.
When the corpse is buried in the soil, so that the corpse can't touch the air, the decomposition speed of the corpse will be normal 1/8, and it will be slower in water. ※.
Generally, people who have been missing for more than seven years will be confirmed dead, and those who have disappeared due to natural disasters or disasters will be confirmed dead for more than one year. ※.
Hitting a person's head with a blunt instrument may even cause a file tear. Usually, there will be no blood spilling from the first blow, but there will be scars around the wound. ※. Only when the second blow is in the same place will the blood come out.
Upper and lower lip mucosal bleeding, neck epidermis peeling, skin peeling bleeding, conjunctival bleeding, etc. Indicating strangulation. ※.
If the deceased was strangled and hit on the head with a blunt instrument, it would cause serious intracranial injury and respiratory failure and die. ※.
Eating a certain amount of sodium nitrite will also kill people. Only a small amount of toxicity enters the bone marrow in acute poisoning. ※.
DNA fingerprints have strong individual specificity, and the consistency between different tissues of the same individual is one in a billion, which is almost the same all over the world. ※.
When the ambient temperature is 1 1-20 degrees Celsius, the average temperature drop in the first 4 hours of the corpse is 0.58/h.
Detective knowledge
Detective reasoning stories are often composed of the following important components: guessing the plot, fascinating interest, magical and ingenious traps, and unexpected suspects. For example, the Japanese detective novelist Edgar Watt Lapol once summarized the examples of unexpected suspects, which can be roughly divided into the following categories:
Detective 1 is a common suspected example. Even detectives are no exception, such as Drewry Rehn and aguirre Boyaro (that is, Poirot). Even Arsène Lupin used to pretend to be Lu Luoman, the head of the security department of the Paris Police Department.
It is also common that the discoverer of a case is a suspect. After killing others, pretend to be the discoverer of the murder scene. There are often similar plots in the novels of Will Dyne and Dixon.
The narrator of the case is a suspect. It is said that it was first written by Duchenne's Diary of Doctor Smirno. Later, agatha christie's novels are also very famous for their handling of this trap (the murder of Roger Ackroyd).
A patient or a physically disabled person is a suspect, which means that a patient who has been lying in a hospital bed for many years makes a plan and then someone else carries it out, such as a novel written by Kuhn. Another example is that people with physical disabilities, such as people without feet, enter the robot to commit murder cases. This phenomenon has appeared in Dickson's novels.
The body is a suspect, and the deceased has a pistol. After a period of time,
Your fingers will become stiff, and then you will pull the trigger and commit murder. Or freeze the body of a dead person and throw it from a height to commit a murder.
6 A child or an old man is suspected to be a child (specifically, a teenager) and has committed a series of murders, such as in Kuhn's masterpiece (The Tragedy of Y). Drury Rehn and Aijul Boyaro also said that old people who enter old age commit murder before they grow old.
7 Doll or heavy object is a trap set by the suspect on Yangyang Eva, which kills people by remote control or time difference. For example, the sunlight reflected by the goldfish bowl acts on the concave-convex lens, causing the matchlock gun to ignite and burn, and the bullet is ejected. (It is to use certain organs to kill people and create the illusion that the suspect is not at the scene. Such as: Kyotaro Nishimura's Scar of an Angel)
There are more than one suspect. For example, the famous murder technique in Christie's famous novel "Murder on the Orient Express" has been made into a movie, which is to let people who are hostile to the victim sit on the same train and let everyone in the same car cut a knife and kill the victim.
Animals are suspects, led by snakes on striped ropes and the strange dog-the Baskerville hound in The Adventures of Sherlock Holmes. Other possible suspects are birds, cats, poisonous spiders and bees. In addition, the suspect in edgar allan poe's Murder on Moge Street is a gorilla.
10 The victim is a suspect or pretends to be a victim, but in fact he is an out-and-out murderer. There are many such examples. Another victim was killed. Turned out to be a murderer. He deliberately committed suicide to sacrifice himself, and then blamed the murder on others (see The Adventures of Sherlock Holmes-The Mystery of Thor Bridge).
Author: detective little lady
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4 Reply: Detective knowledge
Handwriting characteristics and identification methods of handwriting identification
First, related concepts and their relationships
Handwriting is the trace left by writing action through writing tools, which makes everyone's handwriting unique. Through handwriting, it may reflect the habit of using words and making sentences, that is, the habit of written language; In addition, it may also reflect the writer's character layout habits.
Handwriting inspection is a special technique to determine whether it is the handwriting of the same person or the sample is written by someone by comparing and distinguishing suspicious handwriting with the handwriting of a criminal suspect. Its task is to analyze the time by studying the writing habits, text layout and written language characteristics reflected by handwriting, and to provide clues and evidence for litigation.
Writing habit is a skill gradually formed through long-term practice and writing practice, and it is a firm dynamic stereotype established in the cerebral cortex with language and words as the main stimuli.
Writing habits and handwriting are the relationship between objects and objects reflecting objects. Writing action is expressed by handwriting, and writing habits are reflected in writing action. Writing habits can only be expressed by handwriting and can be recognized and used. Because there is no handwriting, it is impossible to investigate writing habits, but to understand writing habits, we must start with the study of handwriting. Handwriting identification is to determine whether the sample handwriting is reflected by the same person's writing habit system by analyzing and comparing the sample handwriting with the appraiser's handwriting, so as to affirm or deny the sample writer according to the similarities and differences of the habit system and provide a strong basis for judicial action.
Writing habit itself has particularity and relative stability. The particularity of writing habits lies in that each writer's writing habit system is specific and unique. When writing a manuscript, some habits are shared by many people, while others are rare or even unique. Those common, rare and unique writing habits constitute everyone's writing habit system, which distinguishes one habit from another. At the same time, writing habits are relatively stable, and its habit system can remain stable for a certain period of time without fundamental changes. The relative stability of writing habits is an indispensable condition for handwriting identification. Writing habit system may be changed by subjective and objective conditions, such as physiological factors, psychological factors, writing tools, personal camouflage, etc., but generally speaking, these changes will not have a fundamental impact on recognition in a certain period of time.
Second, the handwriting characteristics
Handwriting characteristics are the reflection of writing habits. Writing habits and handwriting characteristics are the relationship between reflection and reflection, that is, the relationship between things and objects and reflected images. The most common characters in handwriting identification are Chinese characters, pinyin characters, Arabic numerals and punctuation marks. According to the structure and writing characteristics of Chinese characters, the handwriting characteristics of Chinese characters can be divided into four aspects: the general characteristics of writing action, the characteristics of text layout and the characteristics of written language. This paper mainly discusses the local characteristics of Chinese character writing.
The local characteristics of writing actions are the direct reflection of writing habits, and the concentrated reflection of the spatial position characteristics, action form characteristics, action sequence characteristics and overall characteristics of the text structure composed of several writing actions. The local characteristics of writing actions are the main basis for handwriting identification and identification of writers. Specifically including:
1, writing characteristics. The stroke movement of writing Chinese characters includes three aspects, namely, starting a pen, moving a pen and moving a pen. Writing any stroke has to go through these three stages, so the characteristics of stroke movement are reflected in five aspects: starting characteristics, moving characteristics, moving characteristics, moving characteristics and basic morphological characteristics of strokes.
Because of the different movements of a pen, the whole stroke constitutes a special form, which is called the basic morphological characteristics of strokes, also known as the shape characteristics of strokes. For example, stippling forms vertical points, horizontal points, arc points and sketch points. Stroke movement is the most delicate and complicated writing movement, so it has the characteristics of strong specificity, high stability and high identification value, and is called "the essence of characteristics".
2, stroke intersection *, connection and collocation characteristics. Refers to the characteristics of the relationship between strokes when two or more pictures form part of a single character or a combined character. There are three relationships between strokes: intersection, connection and adjacency, which form the characteristics of stroke intersection, stroke collocation and stroke connection.
Stroke intersection is a feature formed by the intersection or proximity of two or more strokes. It is manifested in the position relationship between the intersection or adjacent points of strokes, that is, whether the strokes intersect, intersect or not. The characteristics of stroke collocation refer to the characteristics of the mutual position and long-short relationship between strokes, including the proportional relationship between strokes and the overall relationship between individual words. Stroke connection feature means that more than two strokes form a unique character or combined character, which is a connection feature formed by completing several strokes with one stroke in the process of stroke transportation without stopping or collecting.
Author: detective little lady
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5 Reply: Detective knowledge
The characteristics of crossing, connecting and collocation of strokes are a special and stable part of personal writing habit system and one of the important bases for handwriting identification.
3. Structural features of Chinese characters. It refers to the characteristics of each component of a combined Chinese character and their relationships. Monograph is a word directly composed of a stroke; A compound word is a word consisting of a stroke and more than two structural units. There are three main structural features of compound words:
(1), written form of structural unit. According to the writing norms of Chinese characters, all parts of the same character have standard writing forms, but due to the differences in writing habits, they may show different writing forms.
(2) Proportional relationship between structural units. Each structural unit of writing Chinese characters requires a reasonable collocation ratio, but most people's habits have broken through this limitation, and its characteristics are: too compact, too loose, asymmetric left and right, uncoordinated size, tight inside and loose outside, tight outside and loose inside, etc.
(3) Variation structure that violates the law of word formation. Because the writer has been influenced by wrong writing habits or regional habits for a long time, he has formed variant structural characteristics that do not conform to the law of word formation.
4, the characteristics of stroke order. It refers to the characteristics of not writing according to the stroke order rules of Arabic and Chinese characters and the writing order rules of components. Shown as:
(1), special stroke order. Such as vertical before horizontal, pressing before skimming, picking before hooking, etc.
(2) The special writing order between the components that combine characters. Break through the conjunction rule, first write the main part of the word together with the strokes, and then write a single stroke that should be written in advance.
5. Special words. Refers to characters that do not exist in the standard font system, but are used in a certain area and a certain group of people. Such as typos, local words, industrial words, coinage, foreign words, etc. Most of them are manifestations of common habits and belong to the characteristics of species; A few are unique habits of individuals, so they have high appraisal value.
To sum up, the local characteristics of writing actions often provide a strong basis for handwriting identification in practice, which is of great significance to the development of handwriting identification activities.
Third, the methods and steps of handwriting identification
Handwriting identification is the same identification, and the whole identification process can be divided into three stages: individual inspection, comparative inspection and comprehensive judgment, and each stage has corresponding and different methods.
(a) respectively.
Respective inspection is to find and determine the characteristics of sample handwriting and sample handwriting;
1, to determine the true degree of handwriting characteristics of building materials. According to the characteristics and case of handwriting, accurately judge the change or disguise of handwriting characteristics and the reason and degree of change or disguise.
(1), if the handwriting proficiency of the sample is consistent, the writing level is adapted to the Chinese level, the strokes are natural, the stroke proportions are coordinated, and the writing movements are regular, it can be considered as normal handwriting.
(2) If the handwriting size and inclination are uneven, the writing speed is inconsistent, and the stroke movement is unnatural, but the writing action is systematic to some extent, and the characteristics of the same word and stroke are basically the same, it means that it is due to objective reasons or other subjective factors other than camouflage.
If the handwriting proficiency of the sample is inconsistent, the writing action is not systematic, the strokes bend intermittently, there are traces of pause and touch-up, the structure and shape of the characters are abnormal, and the skill of the movements is not commensurate with the Chinese level, it can generally be judged as disguised handwriting.
2. Find and determine the handwriting characteristics of the sample. To find the local characteristics of writing, we must observe the handwriting word by word, draw one by one, and find out the regularity of writing, in which the irregular part is the characteristic.
3. Discover and determine the handwriting characteristics of the sample. After preliminarily judging the handwriting characteristics of the sample, the handwriting characteristics of the sample can be determined according to the above order and method. The same features and different features as the sample handwriting should be comprehensively searched and compared.
(2) Comparative test
The main task of comparison test is to determine the same characteristics and different characteristics between the handwriting of the sample and the handwriting of the sample, so as to provide a basis for comprehensive evaluation.
There are four aspects in the comparative experiment:
(1), comparing the similarities and differences of the general features, text layout features and written language features of writing actions;
(2) Compare the similarities and differences of words or strokes;
(3) Compare the similarities and differences of each group;
(4) Comparing the similarities and differences of various features;
For many samples, it is necessary to make an accurate statistical analysis of the same characteristics and different characteristics of the above four aspects, and reflect the similarities and differences of writing habits in quantity and quality by mathematical methods.
The method of comparing the similarities and differences of handwriting features is mainly visual observation, and morphological comparison is carried out with the help of photographic instruments, comparative microscopes and slides.
(3) Comprehensive evaluation
Comprehensive evaluation is to scientifically analyze the numerical values of the same characteristics and different characteristics of sample handwriting and sample handwriting, determine the sum and nature of the coincidence points and differences between them, and then make static conclusions. The method of judgment is generally to start with textual research. When identifying any handwriting, there will be certain differences in characteristics. The key point of judging the difference is to determine the nature of the difference. Its nature has two aspects: essential difference and non-essential difference. Non-essential differences indicate that the proportion of quantity and quality of different features between sample handwriting and sample handwriting is small, while essential differences indicate that the proportion of quantity and quality of different features is large. The former generally shows that they are a reflection of different people's writing habits.
Handwriting identification should not only focus on the judgment of differences, but also on the judgment of overlapping points. It is unscientific to affirm the same conclusion after confirming that differences are non-essential. Coincidence points can also be divided into essential coincidence and non-essential coincidence. If the quantity and quality of the same characteristics of the sample handwriting and the sample handwriting are absolutely dominant, it constitutes essential conformity; If the proportion of the same feature in quantity and quality is small, it belongs to non-essential conformity. After judging the differences and overlapping points, if there are essential differences and non-essential differences between the sample handwriting and the sample handwriting, or the results of essential differences and non-essential differences, it can be concluded whether the sample handwriting and the sample handwriting are written by the same person.