Chapter 297

I confirmed with the victim's husband that the family's smart home system can remotely control not only the lights, but also the bathroom heater and exhaust fan, as well as the air conditioning and ventilation system; the showerhead and bathtub are similarly controllable, including water inflow and drainage...

Captain Ma returned to the scene, describing the situation while unable to resist complaining: "How could anyone connect all their household appliances to the internet? Not only does it let someone else control them, but you also have to pay extra?"

"It should still be pretty convenient."

One-touch hot water: you're sitting on the subway, and the bathtub at home is already filling up; by the time you get back, you can just step in and soak. Doesn't that sound nice? Tang Jia was the first to speak out against it—this was exactly the kind of thing she was willing to do.

Captain Ma snorted: "As if saving a few minutes is worth it..."

Wan Baoming quickly said: "I've called in the tech team—they'll check whether we can find anyone who used this software. If the person was just using it normally, there should be traces left behind."

Jiang Yuan listened to the others speak while silently scanning the bathroom. Whether or not the killer used this system, he had definitely committed the murder and faked the suicide scene—and it had to have happened right in this bathroom.

This greatly increased the probability of leaving traces. Moreover, Jiang Yuan didn't believe anyone could be perfectly thorough. The killer had invested effort into staging the scene, but that didn't mean he had enough time or energy to eliminate all evidence.

Many people hold serious misconceptions about thinking and acting. For example: how much effort and time would it take for a single person to kill a 50-kilogram husky, hang it up, and fake a suicide by hanging? What about cleaning the bathroom? Many people have never even attempted a deep clean of a bathroom. To scrub every corner clean, leaving not a single trace—that would take how much time and energy? What if, halfway through, the killer grew exhausted, slipped, and scraped his elbow? He'd have to clean it all over again. Some reckless individuals might just give up entirely.

Let them give up—then we'll meet them on the execution ground.

These are still killers who know how to act. Some killers have obvious shortcomings in daily life; eliminating evidence after murder becomes even harder.

For instance, some people don't even know how to tie a proper knot. If the noose isn't tied well, lifting a 100-pound corpse becomes exhausting, drenched in sweat, and you have to be careful not to smear the clothes. Then—plop—the rope breaks, and the corpse crashes to the floor. How infuriating, how difficult! Moreover, if the killer wants to fake the scene, many methods become unusable.

Some cleaning agents can indeed destroy DNA, but they're not common household items, or the victim's household never bought them. The killer might then be forced to risk leaving his own DNA behind. This is the unavoidable risk that comes with the benefits of staging the scene.

Jiang Yuan is now betting that the killer didn't clean the scene thoroughly.

His Level 4 Crime Scene Investigation skill can easily spot flaws left by a Level 2 investigator.

An ordinary killer, without professional training—on what grounds would he leave no trace at all?

Of course, modern people who know what they're doing wear gloves—fingerprints are probably gone. But Jiang Yuan collected plenty of skin flakes and hair, especially from the drain and sink, where he found short hairs and wiped up water stains.

The victim had long hair; her daughter also had long hair and lived at school. The victim's husband was partially bald, and what little hair he had left was quite long.

The origin of these short hairs is therefore worth pondering.

Jiang Yuan carefully collected multiple short hairs, placing each into separate evidence bags. He then inspected all the toiletries and wiped down every suspicious spot with a box of cotton swabs, feeling slightly more at ease.

Compared to determining time of death, acquiring physical evidence felt more concrete.

"That's enough." Jiang Yuan directly packed the towel and other items into the large evidence bag.

Solving a murder case isn't the time to save money for the criminal investigation brigade.

Murder is actually exhausting—think of killing a 50-kilogram husky, then hanging it up to fake a suicide.

The bathroom is a sealed environment; breaking into a sweat is normal. If the killer wiped his sweat, the towel might carry his DNA. If he let sweat drip, the water stains he just wiped from the floor might contain his DNA.

If he washed his hands directly with water, the sink he just wiped might hold his DNA.

The power of DNA lies in its extreme sensitivity. In an environment like a bathroom, unless proper cleaning and disinfecting agents are used, even multiple rinses with water may still leave traces of DNA.

But the killer, to fake a suicide, cannot use unconventional cleaning agents—this creates the possibility of leaving DNA behind.

This is the asymmetric warfare between killer and police.

If the killer chooses to stage the scene, he cannot erase evidence. If he chooses to erase evidence, he faces the risk of oversight, plus the hassle and professional demands of carrying various cleaning supplies. He also faces the risk of oversight.

Of course, he could choose not to touch the scene at all, using the shortest possible contact time and method.

But killers often murder to vent emotion; if they can't control their emotional outbursts, they're unlikely to maintain discipline during the act.

On the other hand, even the shortest contact time and method still face surveillance cameras, potential eyewitnesses, and the victim's resistance.

Like Jiang Yuan's previous 513 Door-Stab case—it was already a short-contact case with stacked luck—but once the thin veil of concealment was pierced, the evidence left behind was still substantial.

Still, without Jiang Yuan's analysis of the time of death, which made the husband the prime suspect, the crime scene investigators might not have worked so hard to collect evidence.

Because the husband's DNA would naturally be everywhere in the bathroom; whether there was anyone else's DNA usually wouldn't be deeply investigated.

Who doesn't have a couple of people in their bathroom leaving behind some sweat?

The crime scene investigation team's own officers continued working busily in the living room and bedroom, hoping to collect something else.

Murder cases differ from other crimes—they usually have strong motives.

Without sufficient motive, or a sociopathic personality, one doesn't kill lightly.

In staged crime cases, once the facade of staging is peeled away, the truth usually becomes bluntly clear.

At first, everyone focused on the victim's husband. If the husband didn't kill her, then the killer must have had a close relationship with her.

While they worked, the cybercrime unit technicians arrived.

Like the crime scene investigation kits or forensic kits, network technicians have their own equipment cases, always including devices for forcibly extracting data—typically used against phones, but other smart devices are no exception.

Jiang Yuan and the others stepped outside the door and waited.

The victim's family and several neighbors were taken to the investigation center for statements.

The hallway fell quiet for a moment. Wan Baoming looked around and said: "If it weren't for the smart home system, someone might already be hiding in the ventilation ducts right now."

"Hiding around the corner, waiting for us to leave before jumping down?" Captain Ma played along.

"Maybe the alarm was reported too quickly."

"By the way, the victim's husband came home faster than usual."

"Coming home fast doesn't help—and not trying to save her first, but immediately calling neighbors, that's unusual."

The group murmured by the door.

Soon, the technician stepped out, checking his notes: "Someone did turn on the bathroom heater, showerhead, and air conditioning for heating at 10: 1. At 11: 0, they turned off the showerhead and drained the bathtub. At 11: 5, they turned on the exhaust fan and adjusted the ventilation system's airflow, switching the air conditioning to cooling."

"At 11: 5, they turned off the heater, exhaust fan, and air conditioning." Captain Ma's face grew grim: "Someone really did use this system."

Wan Baoming's expression was equally dark as he turned to the technician: "Can you find out who controlled it?"

"We can only check after returning. If the person was cautious, we might not find anything," the technician said.

Tang Jia spoke up: "Can we check the Wi-Fi's previous connections? Router logs, things like that?"

The technician replied: "We can check. What are we looking for?"

"Murder always has a motive, right? If it's not about property disputes, could this murder be related to emotional issues?" Tang Jia whispered: "The killer clearly knew the victim's home well—he must have visited before to know about these smart home features..."

"Alright, follow this line of inquiry," Captain Ma immediately nodded. "Once we find someone, cross-reference their DNA with what we found at the scene—see if it matches."

-- Proceed to review