Chapter 221: Breakthrough

Luminol reagent is the substance commonly used in films and TV shows to reveal bloodstains.

In earlier years, luminol had to be mixed on-site, but now pre-packaged ready-to-use versions are available.

Luminol has exceptional capability in detecting bloodstains.

How strong? Even bloodstains from several years ago, if not specially treated, can still be revealed.

Even if blood is diluted one million times—such as one drop in a bathtub—it can still be easily detected by luminol.

Therefore, trying to wash away bloodstains with water is essentially futile in the face of luminol.

This is also why it's generally not advised to commit murder at home.

Luminol is very cheap: 0. gram of luminol, mixed with 5 grams of sodium carbonate and 6 milliliters of hydrogen peroxide, can make one 100-milliliter bottle of luminol solution.

It's also applied by spraying, and spraying an entire room takes very little time.

Moreover, modern DNA technology is highly advanced and extremely sensitive; the bloodstains revealed by luminol are softened, making it easy to collect DNA with a simple cotton swab.

Furthermore, ordinary toiletries and cleaning products rarely remove bloodstains to the point where luminol cannot detect them.

To interfere with luminol, you need oxidizing agents—the most common being bleach and potassium permanganate—but even these cannot fully suppress the reaction, because the luminescence duration of hemoglobin differs from that of interferents; experienced crime scene investigators can easily distinguish the difference.

As for hotel bathrooms, these substances are naturally not used.

Besides, the cleaning staff in bathrooms are never known for their diligence.

Before the luminol glow faded, Jiang Yuan took multiple photos, then said: "Master, you can turn on the lights."

"Got it." Wu Jun turned on the lights, his face beaming with joy.

"So happy?" Jiang Yuan put on gloves and a mask, then pulled out cotton swabs and began his procedure methodically.

If all goes as expected, these bloodstains will be the key evidence in this case.

Bai Yuequn's entire web of lies cannot accommodate even a single drop of blood from Yuan Yutang and his boyfriend.

Wu Jun watched Jiang Yuan roll the cotton swabs with a relaxed smile and said: "No matter how cunning he is, he'll still drink my washout water."

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

Wu Jun chuckled, waving his hand in a circle and saying: "Unless both of them burst their hemorrhoids, this is definitely where Bai Yuequn cleaned the blood."

Jiang Yuan grunted, offering a slight correction: "Unless a guest in the past few years burst their hemorrhoids in this bathroom, this is almost certainly where Bai Yuequn cleaned the blood."

"We could be even more precise… but where are the bloody clothes and the murder weapon?" Wu Jun frowned slightly.

In the city, bloody clothes and murder weapons are hard to dispose of; Jiang Yuan had no immediate ideas and said only: "First, break Bai Yuequn's alibi witnesses."

"True. If Xu Yi still won't talk, threatening him with being charged as an accomplice to murder should make him open up." Wu Jun clearly had experience.

Suspects in interrogation are not allowed to see lawyers—they can only hear what the police say. So those who don't study hard, after killing someone or aiding in a killing, are exploited due to information gaps.

Bai Yuequn's fencing teammates looked easy to bully.

…

Evening.

Lei Xin had prepared a meticulous plan and was ready to personally interrogate Xu Yi.

Lei Xin started his career in pre-trial interrogation. In fact, during the time the pre-trial division existed, only officers with exceptional skills were assigned there. His yellowed teeth, stained by years of smoking, were proof of that history.

After carefully reviewing the DNA report once more, Lei Xin walked into the interrogation room with renewed determination.

Xu Yi was tall and thin; once strapped into the interrogation chair, he looked like a giraffe tied up, with only his neck stretched unnaturally long.

"Do you know what we want to ask?" Lei Xin had interrogated Xu Yi before and had brief conversations with him; this time, he sat across with a smile and placed a thick stack of documents on the table.

The pile of documents looked like a mountain of evidence and testimonies, drawing Xu Yi's gaze involuntarily as he speculated silently.

After a while, Xu Yi returned his gaze and said, as if recalling: "I know—you want me to recant."

"I'm trying to save your life, not let you become someone else's scapegoat," Lei Xin decided to go all in. He pulled out several photos from surveillance footage: "These are pictures we took of Bai Yuequn casing the location."

The forensic video team had gathered many clips; Lei Xin showed them to him one by one.

Xu Yi glanced, then turned his head: "No need to show more—that's just the nearest cinema to the bar street. Watching a movie? What's that got to do with casing?"

"That's a reasonable explanation," Lei Xin seized the chance to compliment him, then displayed the footage of the damaged surveillance in Theater 2 and its time stamp.

He followed it with photos of Bai Yuequn entering and exiting the cinema around the same time.

Seeing this, Xu Yi simply closed his eyes and said: "If you can't find the real killer, just arrest us already. Why all these strange things?"

Lei Xin studied his expression, then quietly pulled out his trump card: "I also have a DNA report—collected from your hotel room that night. How do you explain this?"

Xu Yi froze: "What?"

"There's blood from both victims in your hotel room—quite a bit of it," Lei Xin said coolly. "Probably blood Bai Yuequn didn't fully clean up."

Xu Yi hesitated, then said: "You're lying to me."

"Suppose I am lying—suppose I go to your hotel bathroom right now to look for bloodstains. Do you think I'll find blood from the two victims?" Lei Xin held the DNA report in his hand but didn't show it to Xu Yi.

Xu Yi was breaking down.

"Do you really want to spend the rest of your life in prison like Bai Yuequn?" Lei Xin switched to a sympathetic tone.

Xu Yi's expression shifted slightly; after a moment, he said: "There's the job."

"What?"

"Bai Yuequn promised me—if I keep quiet, he'd find me another job. If we're both charged with a crime, finding work will be impossible," Xu Yi whispered.

Lei Xin was thrilled—once he started talking, the rest would be easy.

Lei Xin asked: "Let me ask again: during the movie screening, was Bai Yuequn with you in Theater 2? Did he leave at any point?"

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

Lei Xin nearly snapped—had he been allowed to eat a person, he would have chewed Xu Yi to paste.

"I really don't know," Xu Yi said. "When I entered the theater, I felt tired, so I fell asleep. I don't know when Bai Yuequn left—or if he left at all."

This statement couldn't convict Bai Yuequn, but it was enough to shatter his alibi.

Not just Lei Xin—everyone watching the surveillance footage couldn't help but smile.

Lei Xin pressed on: "What about on the way from the cinema to the hotel? Did you notice Bai Yuequn discard anything?"

Xu Yi said: "No."

"What about smell? Didn't you notice any odor?"

"I was wearing a mask—N95. I didn't smell anything at all."