After finishing the newspaper, Dean drew five or six circles on the city map, with numbers like 1, 2, and 3 marked inside them. Each circle represented a crime, and the numbers indicated the order of their occurrence.

"The first incident happened in a remote city park where public facilities were old and surveillance was almost nonexistent. After the second incident, they all occurred in the urban area, spreading across all four directions—east, south, west, and north. The only area where nothing happened is here!" Dean picked up a pen and drew a large circle on a specific area of the map. The chances are high that the culprit lives in this area!

He turned to Carol. "Did you find any information about the person who sent the newspapers?"

A prison isn't a private place. For humanitarian reasons, criminals' friends and family are allowed to send them letters. However, these letters are opened and closely inspected by the guards before reaching the prisoners, and the sender's details are recorded.

Carol first nodded, then shook her head. "According to the information provided by the prison, the sender was named Jim. I had someone check his details, and it turns out Jim is a distant relative of Xiami who died eight years ago. Someone used his identity to send letters to Xiami."

"That's normal." Dean wasn't surprised by this outcome at all. It was clear from Xiami's accomplice's choice to send newspapers as coded messages that this individual was no fool. The information in the newspapers was jumbled, and the intervals between mailings were irregular.

What was even more disgusting was that every time Xiami found the information he wanted, he would tear off that section and use his semen to stick it to his cell wall, ensuring the side of the newspaper facing outwards appeared normal. Under these circumstances, even if a guard became suspicious of Xiami's strange behavior, they definitely wouldn't be able to stomach tearing off the newspaper stuck to the wall, the side smeared with Xiami's semen. The guards' duty was to ensure prisoners didn't escape, not to solve cases. Therefore, they wouldn't possess the same level of suspicion or the drive to pursue truth that detectives did. Most people also preferred not to meddle in others' affairs.

Carol looked at him, her eyes filled with curiosity. "So where does your confidence to solve the case before clocking out come from?"

"Isn't it obvious?" Dean pointed to the unmarked circle on the map. "The sender's name can be faked, but the handwriting can't, nor can the mailing location! Get me the mailing location of each letter, mark them on the map to further narrow down the area, and then we can directly investigate the residents one by one! Xiami's accomplice is most likely living alone. Even if we don't screen those residents initially, they would have left handwriting samples with the property management. He can't escape!"

Hearing this, Carol slapped her forehead in a moment of sudden realization. Dean's method, while a bit crude, wouldn't be slow with the aid of modern tools, even if it eventually required checking tens of thousands of handwriting samples. The only potential problem was with tenants. Property management companies often photographed signature documents and uploaded them online for record-keeping. If they could obtain this data for comparison, the process would be very quick. However, sometimes the information on file was from landlords, lacking tenant details, which might require more effort.

Once Carol understood all this, she looked at Dean with renewed admiration. "I'm really curious about how your brain works—it seems that no matter the situation, you always find a great breakthrough!"

"It's not that difficult. Just a certain level of intelligence combined with enough experience. Carol, your intelligence isn't lower than mine, but your perspective limits your thinking. If you set aside your pride and observe the world more closely, it will help you grow faster." Dean wasn't stingy with his guidance for this "junior." After all, advice doesn't cost anything. As long as Carol didn't make any serious missteps, her future standing in the Commonwealth would likely be quite high. She was a promising prospect.

This was actually similar to the principle of benefiting from others, like someone living off a wealthy partner. It was about thinking bigger. As long as they weren't his enemy, Dean quite liked making friends like this.

While they were talking, an unfamiliar call came through to Dean's mobile phone. Dean picked it up and saw it was a Commonwealth number. He hesitated for a moment before realizing it must be Nico from the police station. Before leaving, he had left his business card.

Dean answered the call. "Nico?"

"Yes, Mr. Dean! After much effort, we've re-examined the evidence from before and made a significant discovery!" Nico's voice on the other end of the line carried a touch of excitement.

Dean became interested. "Tell me?" Although he already had an idea of how to find Xiami's accomplice, saving some effort would naturally be better.

"In this re-examination, we made two major discoveries. First, on the rope used to strangle the male victim, we found epidermal residue from Xiami and another unknown individual at both ends and in the middle! We extracted genetic material from it. Although we didn't find the other person's information in the database, comparing their genetic material with Xiami's revealed a familial connection! The other person was a relative of Xiami!"

Upon hearing this, Dean immediately pictured the bald face of Jelinton, Xiami's brother. Could this guy have deceived me? He quickly gestured to Carol, who was listening nearby. Carol understood instantly, moved aside, took out her phone, and prepared to have someone check Jelinton's whereabouts when Xiami committed his crimes.

On the other end of the phone, Nico continued, "The second major discovery: we found traces of cobalt on the female victim's bloodied clothes, the axe handle, and the rope!"

"Cobalt?"

"Yes, it's a rather uncommon metallic element. Cobalt commonly encountered by ordinary people is generally used in items like platinum jewelry, dental fillings, and pigment formulations. The key point was that Xiami had sexually assaulted the female victim, but cobalt wasn't found on his clothing. Therefore, these traces of cobalt had very likely been left by the second person!"

As Nico said this, he sighed. Three years ago, they hadn't possessed an X-ray fluorescence spectrometer. Otherwise, even if they had been careless, a routine check would have certainly revealed an unknown accomplice in the massacre from three years ago!

Dean's mood lifted considerably after hearing this. With these two important pieces of information from Nico, locking down the accomplice will be even easier! He paid no mind to Nico's sigh and pressed on, "What other occupations typically involve prolonged exposure to cobalt?"

"Raw material workers, carpenters... That's it!" As Nico mentioned carpenters, he seemed to recall something and exclaimed, "Mr. Dean, I remember now! Three years ago, when I compared the wounds on the victims, I noticed that although the axe wounds on the male and female victims weren't directly comparable, the way force was applied was similar—like chopping wood! At the time, I hadn't considered an accomplice, so I didn't think much of it. Now it seems the accomplice must have had work experience similar to a carpenter, just like Xiami!"

Because of rampant deforestation during the Industrial Revolution, timber resources in the surrounding cities were scarce. This meant the region couldn't support many professional lumberjacks, and consequently, jobs requiring an axe were also uncommon.

Cobalt and the frequent use of an axe. Combining these two points essentially confirmed that the accomplice had worked as a carpenter!

"A carpenter?" Dean sincerely thanked Nico. Nico's findings were very timely. They had really saved him a great deal of effort.

After hanging up, Dean said to Carol, who had just finished her task, "Let's go find Jelinton!"

Carol waved her phone. "I've already verified it. When Xiami committed the crime, Jelinton was detained at the police station; he had no opportunity to be involved! Now that we've confirmed the killer's likely profession, investigating based on your earlier idea will be much simpler!"

Dean shook his head. "The method I proposed earlier wasn't guaranteed to be correct. However, since the accomplice was a relative of Xiami and they had worked together as carpenters, Jelinton must know his identity!"

Having said that, he proceeded to enlighten Carol, who had little life experience, "The profession of a carpenter is unique. Regardless of the country, it typically follows a one-on-one or one-to-many apprenticeship model. It's difficult to set up classes for mass training. Xiami had already changed his profession by the time he committed the crime, but his training experience couldn't be hidden. And this kind of apprenticeship isn't usually found through job applications; it's often through acquaintances. Considering Xiami and his brother were orphaned young, dropped out of school early to make a living, and Xiami eventually became a carpentry apprentice... there's a high probability it was through an introduction from a relative they were in contact with. Jelinton absolutely knows who this person is!"

Dean spoke calmly, "So, going directly to Jelinton will save us a lot more time and effort than my previous method."

Carol blinked, her habitual admiration showing. "Dean, you're amazing!"

This highly intelligent yet inexperienced young woman was almost reduced to a mere fangirl who could only chant '666' in Dean's presence.

Regarding this, Dean silently lit a cigarette. I'd like to keep a low profile, but my abilities just don't allow for it.

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