The young boy brought back by Xu Mo was quite young and appeared timid.
One could tell at a glance that he had just recently entered society.
For Han Fei, who had been in the profession for decades, dealing with someone who had just stepped into society was quite simple.
So much so that he could tell just by looking that this kid wasn't suspicious.
However, to be absolutely certain,
Han Fei still decided to ask more questions to avoid any misjudgment.
"Where were you last night?"
"Last night... I was at school. I was at school all day yesterday," the boy answered.
"School? University? Which school? What's your major?"
"Yes, university. I'm from Yangcheng University, majoring in Financial Management."
"Can anyone verify that you were at school all day yesterday?"
"Teachers and classmates saw me, they can verify it. I also slept in my dorm, my roommates can testify to that."
He answered without any hesitation, seemingly unafraid of investigation, which made Han Fei start to ponder.
This kid wasn't very suspicious to begin with, and now that he said he was at school all day, it completely cleared what little suspicion there was.
Being at school all day meant he had no time to commit the crime.
"You..." Han Fei wanted to ask something else, but was interrupted.
The one who interrupted Han Fei was the forensic examiner.
"Captain Han, the autopsy report is ready, please take a look."
The forensic examiner handed the printed autopsy report to Han Fei.
He didn't directly state the cause of death in front of Han Fei because there was an outsider present, making it inappropriate to speak openly.
Han Fei realized this as well.
After receiving the autopsy report, he immediately stood up and moved away from the young boy sitting at Xu Mo's workstation.
The forensic examiner and Xu Mo quickly followed.
After walking some distance,
The forensic examiner spoke.
"Xu Mo was right, the victim died from poisoning. Tests show that the lethal toxin was ricin, which comes from castor beans. Ricin is extremely potent, and there's no antidote. Once poisoned, death is almost certain."
"Ricin?" After hearing the forensic examiner's words, Xu Mo pondered: "If death was caused by this toxin, then this definitely wasn't suicide. It must be homicide!"
"Why?" Han Fei asked.
"Yes, yes, it's homicide. I was just about to make that conclusion," the forensic examiner looked at Xu Mo with surprise.
He was about to tell Han Fei this, but Xu Mo beat him to it.
It seemed Xu Mo wasn't just skilled in basic autopsy work, but also had knowledge of toxicology!
The next moment, the forensic examiner explained to Han Fei.
"Captain Han, you might not know this, but in toxicology, ricin is known as the perfect poison. It's absolutely the first choice for assassinations. People who die from this toxin are usually assassination victims. If it's not homicide, then it would be accidental consumption of castor beans, but I didn't find any castor beans in the victim's stomach."
"Perfect poison? Why do you say that?"
The forensic examiner struggled to find the right words to answer Han Fei.
Seeing this, Xu Mo continued.
"It's highly toxic and difficult to detect medically. The symptoms often resemble flu, so people usually don't suspect poisoning as the cause of death. That's why it's the perfect poison for assassination. Someone attempting suicide wouldn't choose this toxin because it's hard to obtain. Even if someone wanted to use it for suicide, they would consume large amounts of castor beans, but there were no castor beans in the victim's stomach - only ricin toxin was present."
The forensic examiner nodded.
"Exactly, that's right. The main point is that it's hard to detect, so people usually don't suspect poisoning."
Han Fei furrowed his brow.
When all investigation leads seemed to hit dead ends, Han Fei had wondered if they might have made a wrong judgment.
Whether the victim had committed suicide rather than being murdered.
But now, that theory was disproven.
Although he didn't understand toxicology,
Xu Mo and the forensic examiner had explained ricin to him in the simplest terms.
In their words, this was the perfect poison for assassination - what else could it be but homicide?
The killer chose this toxin clearly because of its difficulty to detect through medical means - they wanted to deceive everyone!
They wanted the police to believe it was an accidental death.
Upon learning this, Han Fei became even more troubled.
What troubled him was that while they could now confirm this was a murder case,
He hadn't found any direction for the investigation, leaving him completely at a loss.
"Could it be a crime of passion?" Han Fei muttered.
After this thought crossed his mind, he became even more troubled.
Among all murder cases, crimes of passion were the hardest to solve.
Because the killer's actions followed no pattern.
They might even kill based on mood, choosing victims randomly, leaving no logic to follow.
Conventional investigation methods couldn't uncover any clues.
After all, before the murder, the killer might have had no connection to the victim, perhaps only meeting them once during the act of murder.
How could they investigate that?
Investigate the victim's social connections? That wouldn't help either!
Just then, Xu Mo seemed to suddenly think of something and spoke up.
"Captain Han, I have an idea."
"What is it?"
"I think we can rule out the possibility of a crime of passion," Xu Mo explained: "Ricin's characteristic is that it's difficult to detect through medical means, which suggests the killer wanted to mislead the police into thinking it was an accidental death. If this were a crime of passion, the killer wouldn't need to go to such lengths to mislead the police."
"The fact that they chose ricin as the murder weapon, doesn't this suggest that the killer actually has a connection to the victim? They didn't dare use more obvious methods because they feared the police would easily trace it back to them as the killer. In other words, the killer's identity is actually quite obvious, we just haven't been looking in the right direction, which is why we didn't suspect them immediately."
Hearing this, Han Fei's eyes noticeably brightened.
"You mean it's hiding in plain sight?"
"Exactly!"