The Untouched Crime

by Zijin Chen

  “This puts me in a really awkward position, you know that.” Zhao sighed.

  “Relax,” Yan said. “I made it perfectly clear to him: I’m not a cop anymore. He knows that nobody is allowed to know that I’m involved in the case.”

  “Oh.” Zhao’s face softened. “Sorry, I got a little worked up there.”

  “Never mind,” Yan said. “You’re a captain; you have to think about your division and your job.”

  Zhao cleared his throat. “So, what have you got?”

  “I’ve made some progress, but I need more evidence.”

  “What did you find?” Zhao said excitedly.

  Yan shook his head. “I haven’t found anything, and before I have evidence, I can’t tell you my theories.”

  “Yan!” Zhao’s face turned red. “You’re afraid that your theory might be wrong and you’ll lose face, is that it?”

  “Basically, yes,” Yan said.

  “You’ve got to be kidding me!” Zhao banged the table with his fist. But Yan was not easily persuaded.

  “Just give me some time,” Yan said, sighing. “This is a real pro. The answers to this case might surprise you.”

  Zhao knitted his brows. Finally he said, “What do you need to find that evidence? I can send someone to help.”

  “I might need some help in the future; I’ll tell you when I do,” Yan answered.

  Zhao watched Yan for a long time. He knew he wasn’t going to get any information out of him. “So what are you going to do next?”

  Yan picked up a piece of chalk from the blackboard. “So far we have six homicides. I think you can simplify it into two categories: five nearly identical homicides with a shocking lack of evidence and the homicide against Xu Tianding. Everything in Xu’s case is different from the previous cases, which is why I think it should be in a different category. Do you agree?”

  “OK, sure.”

  “Now I have to explain a few mathematical concepts. Have you heard of quintic equations?”

  “I know quadratic equations, cubic equations . . .” Zhao was not expecting Yan’s question and didn’t see why it was relevant.

  “Those are all polynomial equations,” Yan said, nodding. “A quintic is a fifth-degree polynomial.”

  “Right. Get to the point.”

  “I’m sure you would have learned about quintic equations in high school or at least in college.”

  “Umm . . . I don’t think so.”

  “Even humanities students learn about quartic equations in high school or college,” Yan said. “Fine, you might not have been introduced to quintic equations before. Quadratic, cubic, and quartic equations all have formulas, so you can always get an answer. Whereas polynomials with a degree higher than four cannot be solved. There aren’t any ready-made formulas for solving them. So what do we do with quintic equations? Use substitution. Make an educated guess about what the answer might be, plug it into your equation, and see if the number was too big or too small. Then adjust your guess accordingly and repeat until you zero in on the true answer.”

  “What the hell does this have to do with the case?” Zhao said, baffled.

  “It’s the same logic for cracking a case,” Yan said with a trace of excitement. “Most cases are simple, like cubic or quadratic equations. All we have to do is investigate, collect evidence, and put all the clues together. But this case is different. There aren’t many clues and we don’t have a suspect, so it’s like a quintic equation. In other words, we can’t use our normal procedure to get to the answer.”

  Zhao squinted at Yan. “If we can’t use our normal procedures to find a suspect . . . what do we do?”

  With a flourish, Yan wrote “substitution” on the board.

  “So you want to find a suspect, assume they are the criminal, and then see if it all fits with the other aspects of the case?” Zhao said.

  “Exactly,” Yan said. “We have to do it backward. Find a killer and then determine whether or not he committed the crime. But all the details will have to line up perfectly.”

  “So do you have a potential suspect?” Zhao asked immediately.

  Yan nodded.

  “Who is it?” Zhao asked urgently.

  Yan pursed his lips. “I can’t tell you until I’m completely sure. I never expected everything to be so complicated. The two categories are totally different, like two quintic equations. And there might be multiple unknowns.” Yan looked out the window. “The first step to solving an equation is determining how many unknowns you have,” he continued. “Then you plug in some numbers and see if they give you the answer you’re looking for. Once I determine the unknowns, I can find some suspects and put them in the equation. If we get the answer we’re looking for, I’ll need your help to collect more evidence.”

  “Alright,” Zhao said, suppressing his impatience. If any of Zhao’s subordinates had wasted his time with a lesson on solving equations, Zhao would have throttled them. But Yan wasn’t a cop anymore. He couldn’t be pushed to work faster.

  “Do you have any theories about the cigarettes left at the scene of the first five murders or those long cuts across Xu Tianding’s chest?” Zhao said.

  “I already told you—we are dealing with far too many variables,” Yan cautioned. “The person who committed the crime is too clever, so we have to go backward. Your questions will be answered only after we check whether our suspect fits the details of the case.”

  Zhao had a sudden desire to burn down the entire mathematics building, but he quickly calmed down. “It’s very unconventional,” he mumbled. “Might as well try it . . .”

  “I have two questions for you,” Yan said.

  “Go ahead.”

  “Are Sun Hongyun’s remains still at the Hangzhou Coroner’s office?”

  “Yes, in the forensic facilities. They haven’t been cremated yet.”

  “Can you get someone to check his neck? I want to see if there are any electric shock marks.”

  “What? Why?” Zhao perked up.

  “I spoke to Luo. The victims were strangled but there wasn’t a struggle. He thought the killer might have shocked the victim with an electric baton. Apparently there was a similar case in Ningbo. That would leave distinct marks on the neck, which is why we need to examine Sun Hongyun again.”

  “Excellent. That Luo is a pro, I tell you,” Zhao said.

  “Of course he is,” Yan said quietly. He turned again to the window.

  “What was your other question?” Zhao asked.

  “Prisoners are required to register their home addresses when they are released, is that right?”

  “Yes, that’s a policy.”

  “Where can I look up the address of an ex-convict?”

  “On the internal website for the Hangzhou Bureau,” Zhao said hesitantly.

  “Can every police officer access that database?”

  Zhao nodded. “The guys working in the prison, members of the Politics and Law Committee, officers at local police stations, and criminal investigators are all able to search it.”

  “So a lot of officers can access the database?”

  “Yes, because every jurisdiction needs to know about ex-convicts in their area. We deal with a lot of cases of recidivism, so we need to know who has a criminal record. Yan, why do you care so much about our database?” Zhao asked.

  Yan changed the subject. “What do you think the killer’s motive is?”

  “He’s taking the law into his own hands,” Zhao said with certainty. “Sun Hongyun and the other victims of the first five homicides were all ex-convicts. Xu Tianding had never been to prison, but he was in the system.”

  “But how do you think the killer found these ex-convicts? How did he know their criminal records?”

  “All the victims lived in west Hangzhou. The killer has probably lived in this area for years. He must have known their histories,” Zhao guessed.

  “But how?”

  “It can’t be that hard to figure out. When there’s a criminal
on your block, everyone is going to hear about it.”

  “You’re not thinking critically, Zhao,” Yan said, shaking his head.

  Zhao was offended. After all, as the captain of the Hangzhou Criminal Investigation Division, he commanded several hundred officers. He frowned. “What do you think?”

  “I can’t imagine the killer going around and asking all of his neighbors who committed crimes. If I gave you a day to try to figure out who had a criminal record just by asking people on the street, you wouldn’t get a single name. Not only that, people would think you were crazy, and it would leave a deep impression. The killer wouldn’t want people to remember him like that.”

  Zhao grunted, but Yan had a point.

  “If someone wanted to identify ex-convicts, the only way is by looking at the database on the bureau’s internal website.” Yan gave him a serious look.

  Zhao couldn’t speak for a few seconds. “Do you think someone in the bureau did this?” he asked in a low voice.

  “Not necessarily,” Yan said hurriedly. “Someone might have hacked the system.”

  Zhao turned away and closed his eyes. Yan’s hypothesis terrified him. What if it was an insider? What if a police officer killed all those people? Even if they solved the case, it would have major repercussions in Hangzhou, not to mention law enforcement. It would be huge.

  Yan saw the worried look on Zhao’s face and said, “Don’t worry; I don’t think a cop did it.”

  “But . . .”

  “I already told you, everything I know is based on assumption. I don’t have any evidence now, but I’m confident that I’ll find the answer soon,” Yan said, determined.

  Chapter 45

  That evening, Investigator Yang told Zhao the results of Dr. Chen’s second autopsy. There was indeed a mark on Sun Hongyun’s neck that could have been caused by an electric baton.

  Dr. Chen also reviewed the photographs of the other four victims. All of them had similar marks on their necks. He concluded that the first five victims were also attacked by electric batons and then strangled to death. But the sixth victim—Xu Tianding—didn’t have the mark.

  Zhao nodded. As Yang was about to leave, Zhao stopped him. “Go and tell Professor Yan everything that Dr. Chen told you,” he said.

  “Yes, sir,” Yang said.

  “One other thing,” Zhao said, hesitating again. He stood up and approached Yang. “I want you to arrange for someone to follow Professor Yan for the next few days. Be discreet; I don’t want him or anyone else to know.”

  “Sir?” Yang looked confused before his eyes widened. “You think Yan is the killer?”

  “Nonsense!” Zhao huffed. “Where did you get that idea? He’s not brave enough to kill someone.”

  Yang lowered his head awkwardly. “Then . . . why do you want to follow him?”

  Zhao frowned. “He says he’s already found some clues, but he won’t tell me anything! I want to know where he’s going and who he’s seeing. Ideally the officer tailing him could take pictures. Yan never reveals exactly what he’s thinking, but this time I think he’s hiding something important. You have to keep this strictly confidential. Understood?”

  “Of course,” Yang said, nodding. “But what is Professor Yan doing in the bureau in the first place? He’s not a cop. That’s . . . not really appropriate, is it?”

  “He used to be a criminal investigator—one of the best. Then something horrible happened.” Zhao paused. Yang was young, but Zhao didn’t see any reason to hide the story. “He used to be part of a team of criminal experts for the Zhejiang Public Security Bureau.”

  “Really?” Yang’s mouth fell open. He knew that it was very difficult to be selected for the criminal expert team. It was one rank below the head of the Zhejiang Bureau. Yan must have been a phenomenal investigator and very well known.

  “Yan Liang was also a guest professor at the Zhejiang Police Academy,” Zhao continued. “He helped the higher-ups in government solve cases when they were still working at the local level; they held him in the highest respect.”

  “Then what is he doing teaching math at Zhejiang University?” Yang asked incredulously.

  “He got emotionally involved in one of his cases,” Zhao said, looking out the window. “About five years ago, sometime in October, construction on some new high-rise apartments in east Hangzhou was stalled,” Zhao said. “It was supposed to be finished at the beginning of the year, but the real estate company had cash-flow issues. The boss took the money and ran off. The whole project turned into a bunch of unfinished buildings. The district government looked into it and decided to let a state-owned enterprise acquire the real estate company. They would only have to add plumbing and electricity. Still, it took the better part of a year before the apartments were made available to the flat buyers.”

  Yang nodded, listening closely.

  “Then on the day that the proprietor came to inspect the buildings, they found a body on one of the rooftops. It had decayed so much that only a skeleton remained—the coroner could only determine that the victim was male and killed approximately three months before by a strike to the back of the head, where a hole was found in the victim’s skull. He guessed that the victim had been killed in June and rotted away over the course of a summer. The police did not find an ID card or any articles of clothing to help identify him.”

  Yang’s eyes widened.

  Zhao nodded grimly. “Roof access was protected by a locked iron gate. We’re talking a very secure door; only a hand could fit between those iron bars. There’s no way an entire person could squeeze through. According to the real estate company, the door was never broken into during the six or so months that the project was suspended. There were no marks to suggest that the gate was forced open. The key was kept in a drawer in the real estate company’s office, where a director was responsible for keeping it safe. She was pregnant and had a strong alibi, so she was eliminated as a suspect.”

  “How is that possible?” Yang asked, squinting in confusion. “The gate was not damaged and never opened. The key was in good condition and safely kept in an office. There’s no way the victim could have gotten up there, let alone his attacker. Maybe the killer used a machine to get the body onto the roof?”

  “It’s a high rise,” Zhao said, shaking his head. “Twenty floors.”

  Yang pursed his lips.

  “The district bureau discovered the victim’s identity a few days into their investigation. A middle-aged woman had reported her husband missing in June. She lived in an older neighborhood close to the high rise in question. The police compared the DNA and it was a match. The police learned more about the situation after interviewing the woman, her teenage son, and a few of the neighbors. The family was very poor, but the man still wasted money on drinking, gambling, and entertainment. Sometimes he would not come home for several days. He had many affairs,” Zhao explained.

  “But all the evidence was three months old, and nobody could figure out how the body got on the roof. How was the case solved?” Yang asked.

  “From the face of it, the rooftop seemed completely closed off. It garnered a lot of attention because a lot of people were at the scene when the body was discovered. Still, the district bureau was unable to find any leads. The Zhejiang government put Yan on the case. His specialty is the type of case that seems to defy logic. He quickly deduced that the killer used a drill to remove all the bolts from the door, removed the entire door, laid the body on the rooftop, and finally put all the screws back in place.”

  “Oh!” Yang said.

  “After interviewing the victim’s wife, Yan quickly discovered inconsistencies in her testimony. Then he found a power drill at her house. Yan accused her of the crime, and she admitted to it.”

  “Wow.” Yang couldn’t think of anything else to say.

  “She said that her husband was always gambling and carousing,” Zhao explained. “He frequently came home drunk, and if she or her son said the wrong word, he would beat them. The
ir son was a sophomore in high school. He wanted to take summer school classes to have a better chance to pass the college entrance exams, but he needed five hundred yuan for the fees. The father had lost a lot of money gambling that night, and he lost his temper. The woman couldn’t bear to watch her son mistreated anymore—it was the final straw. The next day while her son was at school, she struck her husband in the head with a hammer.”

  “And then what happened?” Yang asked.

  “She needed to hide the body, of course,” Zhao said. “She remembered the new flats being built nearby and was certain that there weren’t any security guards there. In the middle of the night, she dragged the body all the way to the roof and then reported her husband missing a week later. She even fooled her own son.”

  “That’s incredible,” Yang said, shaking his head.

  “She went to the station a few more times to follow up so the police swallowed the bait,” Zhao said. “They even felt bad when she was caught because her husband was a real bastard. Still, homicide is inexcusable. The best they could do was collect some money for the son’s college tuition.”

  “Where did Yan go wrong?” Yang asked, clearly confused.

  “You didn’t notice anything wrong with that story?” Zhao said.

  “What do you mean?” Yang asked awkwardly.

  “How could a middle-aged woman carry her husband up to the roof of a different building? Even if she had the strength, how did she remove all the screws on the iron gate?”

  He knitted his brows and tried to work it out. “Did her son help her move the body?”

  “She wasn’t the killer at all: it was her son,” Zhao said. “Two weeks after the mother was taken into custody, the son turned himself in. He claimed his mother took the blame to try and protect him. On the day he asked for money, the drunk father started beating him, and the mother stepped in between, trying to protect him. Watching his father lay a belt on her put the son over the edge. He grabbed a hammer and used all his might to strike his father on the head. The mother went into shock. The son wanted to turn himself in.”

  “But that didn’t happen, obviously,” Yang said.