The deceased's name is Ning Xiaobai, female, 23 years old this year, student, is preparing for the year-end graduate exam, due to the pressure of preparing for the exam, she is ready to learn piano to relieve pressure and cultivate sentiment.

The policeman's name is Zhang Yajing, female, 28 years old this year, graduated from the Conservatory of Music, piano grade 10, and is currently a music interest class teacher and private teacher.

Zhang Yajing is Ning Xiaobai's personal teacher, and she came to class on time today, but found Ning Xiaobai's body.

The crime scene was in Ning Xiaobai's rental house, and Ning Xiaobai needed a quiet review environment because he was preparing for the graduate school entrance examination, so he moved out and lived by himself. Last year, she failed the graduate school entrance examination, and this year's World War II was very stressful, which made her feel extremely anxious. Because there was a piano in the rental house, I had the idea of learning piano.

Zhang Yajing briefly told us about Ning Xiaobai's natural situation.

The technical team first entered the scene of the crime, quickly found an open space with almost no traces of physical evidence in the living room, and built a passage into the scene of the crime to prevent the physical evidence on the ground from being destroyed by subsequent technicians.

Ning Xiaobai's body was in the bedroom, she was lying on her side on the ground, with a string wrapped around her neck, and no blood was found at the scene.

"How long have you been teaching her piano?" I walked into the scene of the crime, stood in the living room, and suddenly asked Zhang Yajing beside me.

"Oh, I've been a personal trainer for her for three months." Zhang Yajing had slowly stabilized from her sad mood and said in a deep voice.

"Three months? How did you meet, and how often do you give her lessons? I nodded slightly, crossed my hands on my hips, and asked slowly.

Zhang Yajing stood beside me, her hands clasped together, although she no longer cried, she was still extremely nervous in her heart.

"Instrument lovers like them and students who are just starting out will have their own interest groups, and then there will be teachers in the group, and everyone can sign up for classes or hire private teachers according to their own ideas and situations. I came to give her private lessons twice a week, once on Wednesdays and once on Sundays, for two hours each time, and today is Sunday. Zhang Ya looked at me quietly and said seriously.

I nodded slowly, and didn't speak again, everything had to wait for the results of the on-site investigation and preliminary autopsy.

In many criminal cases, there are many cases where murderers have reported to the police after murder, and our serious crime team has also encountered several cases in the investigation.

The deceased lived alone, and Zhang Yajing was the first to find the deceased, and the most important thing was that because Zhang Yajing had the key and entered the deceased's room.

Judging from the current situation, Zhang Yajing is the direct suspect.

I walked into Ning Xiaobai's bedroom, where forensic doctor Ren Qiushi and forensic assistant Zeng Lan were seriously conducting an autopsy.

The strings were still wrapped around Ning Xiaobai's neck, it was a silver-white string, relatively thick, it looked like a kind of steel wire, it should be a piano string.

"The strings completely wrapped around the neck of the deceased, there were no other wounds on the body, there were no blood stains at the scene, there was a deep groove on the neck, there were slight lacerations on the surface of the skin, and there were traces of bleeding under the skin, the deceased should have died of suffocation caused by strangulation." Zeng Lan observed it for a moment and said seriously.

Ren Qiushi nodded, the situation at the scene is still relatively intuitive, the deceased is most likely strangled to death, whether there are other causes of death and suspicions, and an autopsy is still needed for further examination.

"Since it was a death of suffocation, the first thing to determine was suicide or homicide." Ren Qiushi said lightly, and then reached out to check the deceased's hands.

In the course of strangulation, the deceased will put up a violent resistance, and there will be obvious resistance injuries or signs of resistance on the hands.

The most common is the inversion of the hands, the five fingers are claw-shaped, and occasionally there will be body surface trauma.

However, Ren Qiushi found strangulation marks on the deceased's hands, which were ring-shaped, around the palm, and there were slight lacerations and traces of subcutaneous bleeding.

Combined with the ring-like bending marks at the ends of the strings that wound around the neck, the strangulation marks on the deceased's hands were also caused by the entanglement of the string wires.

"Did the deceased strangle himself to death?" Ren Qiushi frowned suddenly, very shocked by this conclusion.

"Without the help of any external force, the deceased's hands grabbed one end of the string and strangled himself to death with force on both sides? How is that possible?! Zeng Lan was also very surprised by this.

Under normal circumstances, it is impossible for a person to strangle himself to death, just as it is impossible for him to hold his breath and suffocate himself to death.

Psychologically speaking, human beings have an innate survival instinct, and when their lives are seriously threatened, they will immediately resist, and when human beings survive, their potential is infinite, and the ability to burst out in an instant is very powerful. If you commit suicide without external help, you will stop the suicide immediately.

Physiologically speaking, when a person strangles himself without the help of external force, when the strength and time reach a critical value, he will be powerless due to lack of oxygen and have no ability to continue to exert force. At the same time, when people are extremely hypoxic, they will faint, and they will also have no ability to continue to exert their strength, and then they will be treated or self-recovered according to the situation, and they will slowly wake up.

Although not fatal, prolonged hypoxia can cause irreversible damage to the brain and should never be attempted.

This is also where Ren Qiushi and Zeng Lan feel very strange, but what is even stranger is the strings that are used as murder weapons.

The diameter of the string is very thin, and the toughness is strong, when the force is large, the string will cut into the flesh, the initial stage will cause subcutaneous bleeding to form transverse incisions and congestion lines, if the force is strong enough or strong enough, it can completely cut off the carotid artery or jugular vein.

But in this case, apart from a slight skin split, there was no more serious trauma, but the cause of death of the deceased was suffocation, which was caused by the compression of the strings that closed the airway and compressed the arteriovenous vessels in the neck.

In any case, the tool that caused Ning Xiaobai's death must be this string.

"Could it be that the deceased did not have enough strength when he committed suicide, or that he killed and disguised himself as suicide?" Zeng Lan asked in a deep voice.

Ren Qiushi thought for a while and said seriously: "There is only one groove on the neck of the deceased, and the groove is the same as the strings. It is true that suicide cannot cause a slit of the neck arteries and veins, but if it is a homicide, the strangulation marks on the palm of the hand have a life reaction. Unless ......"

"Unless it's assisted suicide?" Zeng Lan suddenly frowned, looked at Ren Qiushi and said.

Ren Qiushi pondered for a moment, nodded slowly, and said in a low voice: "If the deceased's hands are wrapped around the strings and he wants to strangle himself, and there is one who holds the deceased's hands and helps to exert force, it will indeed cause this kind of crime scene......"