Chapter 221 Breakthrough

Luminol reagent is a reagent often used to show blood in film and television works.

In the early years, luminol needed to be configured on site, but now there are packaged finished products available.

Luminol has super ability in detecting blood stains.

How strong is it? Blood stains from a few years ago can be shown without special treatment.

Even if the blood is diluted 1 million times, that is, one drop of blood in a bathtub of water, it can still be easily detected by luminol.

Therefore, it is basically futile to use water to wash away blood stains in front of luminol.

This is also the reason why it is usually not recommended to kill people at home.

Luminol is a very cheap reagent. 1 gram of luminol, 5 grams of sodium carbonate, and 6 milliliters of hydrogen peroxide can be filled with a bottle of 100 milliliters of luminol solvent.

Moreover, the current DNA technology is also very advanced and highly sensitive. The blood stains sprayed by luminol just soften the blood stains. With a cotton swab, it is easy to make DNA when you go back.

Moreover, it is difficult to clean blood stains to the extent that luminol cannot be detected with general toiletries and cleaning products.

To interfere with luminol, oxidants must be used, the most common of which are bleaching powder and potassium permanganate, but they cannot completely interfere with the luminol reaction, because the luminescence time of hemoglobin and the interference term is different, and experienced on-site inspections can easily find the difference.

As for the hotel bathroom, these things will naturally not be used.

Besides, the cleaning lady in the bathroom has never been known for her diligence.

Jiang Yuan took several photos before the luminol glow ended, and then said: "Master, you can turn on the light."

"Okay." Wu Jun turned on the light, his face full of smiles.

"So happy?" Jiang Yuan took out gloves and masks and put them on, then took out cotton swabs and operated in a methodical manner.

If nothing unexpected happens, these blood stains will be the key evidence of this case.

Bai Yuequn's full set of lies cannot accommodate a piece of blood stains of Yuan Yutang and her boyfriend.

Wu Jun looked at Jiang Yuan rolling the cotton swab with a relaxed look on his face, and said: "No matter how cunning he is, he has to drink my dick washing water."

"We haven't done the DNA test yet." Jiang Yuan reminded him.

Wu Jun laughed, drew a circle with his hand, and said: "Unless both of their hemorrhoids burst, otherwise, this must be the place where Bai Yuequn cleaned the bloodstains."

Jiang Yuan said "yeah" and corrected slightly: "Unless in recent years, a guest's hemorrhoids burst in the bathroom, otherwise, this is basically the scene where Bai Yuequn cleaned the bloodstains."

"It can be more rigorous, but... where are the blood-stained clothes and the murder weapon?" Wu Jun frowned slightly.

In the city, blood-stained clothes and murder weapons are more difficult to deal with. Jiang Yuan didn't have any ideas for a while, and only said: "First break Bai Yuequn's alibi."

"That's right. If Xu Yi doesn't say anything, he will open his mouth if he is threatened by the accomplice of the murder case." Wu Jun is still quite experienced.

Criminal suspects cannot see lawyers during the interrogation stage. They can only listen to what the police say. Therefore, if they do not study hard and kill people or accompany others to kill people, they will be exploited because of information asymmetry.

Bai Yuequn's fencing teammates look easy to bully.

...

In the evening.

Lei Xin made a careful plan and prepared to interrogate Xu Yi in person.

Lei Xin started his career as a pre-trial officer in his early years. In fact, when there was a pre-trial department, the police officers who could enter the pre-trial department were all strong in professional ability. His teeth stained yellow by cigarettes are also a historical proof.

After carefully reading the DNA report again, Lei Xin walked into the interrogation room with high morale.

Xu Yi is tall and thin. After his hands and feet were locked by the interrogation chair, he looked like a giraffe playing with bondage, only his head stretched out very long.

"Do you know what we want to ask?" Lei Xin was not the first time to interrogate Xu Yi. He had a brief conversation before. This time, he sat opposite with a smile on his face and put down a thick stack of documents.

The pile of documents looked like a lot of evidence and testimony, which attracted Xu Yi to look over and guess in his heart.

After a while, Xu Yi turned his eyes back and said, "I know, you want me to change my confession."

"I want to save your life, I don't want to see you become a scapegoat." Lei Xin decided to use a trick, first took out a few photos of surveillance video, and said, "These are the photos we took of Bai Yuequn scouting the place."

The picture detection team found a lot of videos, and Lei Xin showed them to him one by one.

Xu Yi looked at it, turned his head and said, "No need to show it, that's the nearest movie theater on the bar street, just go to the movies, it's not a scouting place."

"Your explanation has some substance." Lei Xin took the opportunity to praise Xu Yi, and then showed the picture and time of the damaged surveillance in the No. 2 projection room.

Then showed the photos of Bai Yuequn entering and leaving the theater at about the same time.

Seeing the back, Xu Yi simply closed his eyes and said, "If you really can't find the murderer, just arrest us directly, why bother with so many inexplicable things."

Lei Xin looked at his expression and silently took out his trump card, saying, "Here, I have a DNA report, which was collected from the hotel room you stayed in that night. How do you explain this?"

Xu Yi was stunned: "What do you mean?"

"There are a lot of bloodstains from the two dead in your hotel room." Lei Xin said calmly, "It should be the blood that Bai Yuequn didn't clean at the scene."

Xu Yi hesitated for a moment and said, "You lied to me."

"Suppose I lied to you, I will go to the bathroom of the hotel you stayed in to look for bloodstains. Do you think I can find the bloodstains of the two dead?" Lei Xin held the DNA report in his hand and didn't give it to Xu Yi.

Xu Yi couldn't hold it anymore.

"Do you really want to be in jail for life like Bai Yuequn?" Lei Xin began to use sympathy offensive.

Xu Yi's expression changed slightly, and after a while, he said, "There is still work."

"What?"

"Bai Yuequn promised me not to talk nonsense and find me another job later. If we are both convicted of a criminal offense, it will be difficult to find a job." Xu Yi's voice was very light.

Lei Xin was overjoyed. As long as he opened his mouth, it would be easier to ask questions later.

Lei Xin said, "Then let me ask again, during the movie screening that day, did Bai Yuequn watch the movie with you in the No. 2 projection room, and did he leave in the middle?"

Xu Yi said, "I don't know."

Lei Xin couldn't hold it back immediately. If he was allowed to eat a person, he could grind Xu Yi into pieces in his mouth.

"I really don't know." Xu Yi said, "I felt a little tired when I entered the projection room that day, so I fell asleep. I don't know when Bai Yuequn left or whether he left."

This sentence cannot incriminate Bai Yuequn, but it is enough to dismantle Bai Yuequn's alibi.

Not only Lei Xin, but everyone watching the surveillance video couldn't help but laugh.

Lei Xin continued, "Then on the way from the cinema to the hotel, did you notice anything Bai Yuequn threw away?"

Xu Yi said, "No."

"What about the smell? Didn't you smell it?"

"I was wearing a mask at the time. It was an N95 mask, so I didn't smell it anyway."