Coroner Coroner

"People who arrive early may sit on this rock to rest, and if they get impatient after waiting for a long time, they may be idle and bored, and pull out a few blades of grass in front of them."

The traces produced by humans resting and waiting here further confirmed Lin Xinyi's previous guess.

He believed that the murderer and the deceased had made an appointment to meet here.

One of them arrived at the scene earlier and sat on the rock to rest and wait.

"This..." Officer Jiang Gu felt that Lin Xinyi's guess was too wild and unconstrained.

Vulnerabilities can be found as soon as they are found, for example:

"Mr. Lin, how can you be sure that these blades of grass were pulled out by the murderer at the time of the crime, or when the deceased was resting?"

"You must know that the Gunma County Police just came here a few days ago."

"These grasses might have been pulled out while they were sitting here resting when they were tired from surveying the site."

"And the climbers who found the bodies... They have also been here, and they may have sat here to rest."

"I can rule out both theories."

Lin Xinyi said calmly.

He squatted down slightly, picked up a blade of grass and said:

"This thing is called Xiao Pengcao, also known as Canada Flying Peng."

"It is an invasive species native to North America, and it is now widely distributed in the mountains and forests of East Asian countries."

Small peng grass is also widely distributed in China.

Lin Xinyi once used this plant as a clue to solve the case in a field survey, so he has a fairly good understanding of the growth habits of the small peng grass.

"This small grass can grow up to 70~130cm in adult stage, or even higher."

"However, the piece of grass we see now is generally only about 10cm long, and it is still in the young stage."

"And these uprooted small ponchos are even shorter."

"They stopped growing after they were uprooted, so compared with the surrounding small grasses that have grown to 10cm in the same period, the longest stems of these withered yellow grasses after being pulled out are only 4 or 5cm long."

"This..." Officer Jiang Gu quickly understood: "Mr. Lin, what do you mean..."

"Comparing the length of these dry grass stems with the height of those grass stems that have always grown normally, you can roughly judge when those small grasses were uprooted?"

"That's right." Lin Xinyi explained in a straightforward manner:

"The growth period of Xiaopeng grass is about 6 months. The leaves and stems are tender in late March every year, with a stem length of 3-2cm, and the stem length is 4-4cm in early April. After that, it enters the growth period and grows rapidly."

What he memorized was still data from a certain place in China, so there would definitely be errors when copying it.

But now it is enough to have an approximate time frame, and it does not matter if the error is large.

And the climate change in this mountainous area in the past month happened to be similar to the field climate in March and April every year in a certain place in China, which is the source of Lin Xinyi's data.

So Lin Xinyi copied the data and used it:

"The length of the cut grass stays at 4 or 5 cm."

"The living grass growing normally next to it has grown to 10cm now."

"According to the growth habit of the small peng grass, it is not difficult to judge..."

"The time when these grasses were uprooted from the soil should have been 10 days ago, within 20 days."

The time for the blades of grass to be pulled off is 10-20 days.

The approximate time of death of the deceased was between 10 and 18 days.

The two time periods coincided by coincidence.

And since the blade of grass was pulled out at least 10 days ago, it cannot be pulled here by those climbers and the county police of Gunma County just a few days ago.

"The person who is most likely to sit here and rest, bored and pull out these grass stalks, is the murderer or the dead!"

Lin Xinyi gave his own conclusion.

But Officer Jianggu still hesitated:

"Although the police officers of the Gunma County Police are excluded, there are also those climbers who found the body."

"However, this does not fully prove that these blades of grass were pulled out by the murderer and the deceased."

"What if another group of climbers came here before the incident and sat here to rest?"

"It's very unlikely."

"After all... this forest is not close to that mountain road, even mountaineers may not come here."

"It is already a very small probability that a group of climbers accidentally broke into here and found the body."

"It would be too coincidental to say that there was another group of climbers who came here before the incident."

Lin Xinyi knew that even though the probability of the possibility mentioned by police officer Jianggu was small, it was indeed a possibility.

This possibility cannot be ruled out.

"But we don't need to rule it out either."

A smile appeared on the corner of Lin Xinyi's mouth:

"We just need to know that the murderer or the deceased may have sat here, rested and waited, and pulled the weeds impatiently."

"With this guess and this possibility, we have a direction for the next step of investigation."

"Oh?" Police officer Jiang Gu was a little puzzled:

It is known that one of the murderers or the dead may have sat and waited here.

At best, this seems to barely confirm that the murderer and the deceased did not come here at the same time, and prove Lin Xinyi's previous guess that "the murderer and the deceased had an appointment to meet here", right?

But even if these speculations are true, so what?

Knowing that some of them had rested here, knowing that they had made an appointment to meet here, would it really help to solve the case?

How can we help the police find out the identities of the murderer and the deceased from the vast crowd?

Officer Jianggu was a little puzzled.

He cast curious and expectant eyes on Lin Xinyi.

Lin Xinyi did not answer directly.

He just took out his mobile phone and said with a mysterious smile:

"Officer Jianggu, wait a minute."

"I'll send a text message and ask my friend to check it for me."

"If we're lucky, the case might be solved right away."

Officer Jianggu: "???"

With the few clues they have, they don't even have a clue about the identity of the deceased and the murderer...

How could this case be solved directly?

Even with his mind, Rao couldn't help being a little confused.

But Lin Xinyi knew that it was not because Officer Jianggu was out of his mind, but because he lacked experience in criminal investigation.

This kind of experience is the experience of using information and communication technology to solve crimes.

To put it simply, it is to check the mobile phone number.

According to Lin Xinyi's conjecture and deduction:

Since the murderer and the deceased had made an appointment to meet in this wilderness, in order to keep in touch, it was impossible for them not to bring their mobile phones.

And if they brought their mobile phones, one of them rushed to the scene early, sat on the rock and waited, waiting so boring that he had to pull weeds to pass the time...

Then the person who arrived at the scene first got impatient, so wouldn't he take out his mobile phone and call to ask when the other party will be able to arrive for the appointment?

And if the murderer and the deceased, they called each other on this mountain, then...

"Noah's Ark."

"Can you help me check all the call records of the local telecommunications company in the past 10-20 days?"

"The address is xx village near Mount Haruna, Gunma Prefecture, the forest outside the village."

"There is a signal base station in this mountainous area."

"I want you to check whether, among the callers who dialed through this base station in the past 10 to 18 days, anyone has recently registered as 'missing' in the police system."

Lin Xin sent his own question to the artificial intelligence assistant via text message.

Noah's Ark replied quickly:

"of course can."

"I can help you check all the call records transferred through the local signal base station within 10 to 18 days."

As long as the mobile phone is in the activated state of the mobile phone card, it will generally automatically connect to the base station that is closest to you and has the best signal.

As long as someone calls here, the corresponding dialing record will be left on the local base station.

As long as the call record data of the telecommunications company is retrieved, it is possible to know who has called whom through a certain base station in a certain area during a certain period of time.

The principle is actually very simple.

It's not technically difficult either.

But the reason why Officer Jianggu and Belmode didn't think of this at this time is...

In this era of underdeveloped communication, even in the future of advanced technology, very few people solve crimes in this way.

Because in densely populated areas such as urban and rural areas, a base station may have tens of thousands of incoming and outgoing call records every day.

The base station can only record the dialing number, but not the content of the call. It is simply impossible to find the call made by the murderer from so many dialing records.

Because of this, this "stupid method" of confirming the murderer's phone number by checking the massive dialing records of the base station, no matter what era it is in, rarely has a chance to appear.

Officer Jianggu and Belmode had never seen this method of solving crimes before.

That's why they can't figure out these joints.

However, Lin Xinyi has learned many classic cases during his work, and knows that in sparsely populated rural areas, he can try to use this method of checking base station dialing records to confirm the phone number of the person involved.