"The time is 13 days ago, from 1:13:31 to 1:15:07 in the afternoon."

"The number was dialed from the 'remote base station' you mentioned."

"The base station where the call recipient is located is also this base station."

"Only one?" Lin Xinyi was surprised and typed quickly on the keyboard in response: "And the person who answered the call was also within the signal coverage of this base station at the time?"

This means that the two people who called and answered the phone were both on the mountain at that time, not far apart.

This is exactly consistent with Lin Xinyi's previous reasoning: "The murderer and the deceased made an appointment to meet here, and the first arrival waited for a long time and called the other party to inquire."

This alone can basically confirm that this phone call was made between the murderer and the deceased.

But this still needs to be proven——

The most direct way to prove it is:

"Noah's Ark."

"Did you find out that any of the parties to this call were registered as 'missing' in the police system?"

The deceased has passed away quietly for more than ten days.

In the ten days since she was "missing", her relatives and friends may have reported the case to the local police nearby, causing her to be registered as a "missing person" in the police system.

Just compare the identity information of the owner of the mobile phone number with the national missing persons records to see if there are any identities that match each other...

It can prove whether the two people who made the phone call in this mountain at that time were the deceased and the murderer in this case.

The identity of the deceased and the identity of the murderer can also be easily determined.

This is not technically difficult.

For Noah's Ark, an artificial intelligence that can be called an alien creation, this should be a piece of cake.

But what Lin Xinyi didn't expect was...

"Feel sorry."

Noah's Ark gave a negative answer:

"The mobile phone numbers of both parties on the call have not been registered with their real names."

Lin Xinyi forgot. In this day and age, real-name registration is not required to open a mobile phone number.

If you want to find out the identity of the owner from the mobile phone number, you have to spend some extra effort.

And most importantly...

"You made a mistake."

There is helplessness between the lines in Noah's Ark:

"As far as I know, your country has not yet established a nationwide networked police data system."

"Including the Tokyo Metropolitan Police Department, many places still use paper documents to record data."

"The 'missing persons database' you call does not exist at all."

"However, in the name of the Tokyo Metropolitan Police Department, I can help you send investigation assistance emails to local police stations across the country, asking them to fax over their respective missing persons files."

"Of course, these paper materials..." Noah's Ark added with disgust: "You have to read it yourself."

Lin Xinyi: "..."

"Okay..." Lin Xinyi finally realized that he was temporarily excited and mentally "traveled back".

Noah's Ark may be science fiction, but it is still behind the times.

This artificial intelligence was born a little too early.

Otherwise, it will become Skynet in a minute, and controlling the world will not be a problem.

Now Noah's Ark cannot help, and Japan does not yet have a nationwide online missing persons database... So what should we do?

Are you really going to look through those paper documents that were faxed over?

When will it be turned over?

Just thinking about the sea of ​​paper in the book made Lin Xin's scalp numb.

"Noah's Ark, is there no other way?"

"Yes." The artificial intelligence replied: "I can help you try to retrieve the text message records of these two numbers, and try to confirm the identities of the two phone number owners through intelligent analysis of the text message conversation content."

"But this will take some time."

"And beyond that..."

Noah's Ark quickly gave another solution to the objection:

"I can also help you locate those two mobile phone numbers and determine the approximate location of the owner."

These days, mobile phones don’t have GPS installed yet.

But Lin Xinyi knew that the mobile phone positioning mentioned in Noah's Ark should refer to the base station positioning method that already existed in this era:

Usually, in a city, a mobile phone will be covered by multiple base stations.

The mobile phone will "measure" the downlink pilot signals of different base stations and obtain the signal TOA (time of arrival) or TDOA (time difference of arrival) of each base station.

Based on this measurement result, combined with the coordinates of the base station, the coordinates of the mobile phone can be calculated.

The error of this positioning method is generally more than 100 meters.

Moreover, the fewer base stations in the target area, the greater the error.

If it is in a sparsely populated mountainous area with only one signal base station within a few kilometers, then the error can be as large as several kilometers.

This method of mobile phone positioning will definitely not be too accurate.

But if we can know the approximate location of the murderer through mobile phone positioning, it will be more or less helpful in solving the case.

So Lin Xinyi waited expectantly for Noah's Ark's response.

Not long after, Noah's Ark sent him another text message:

"Among the two mobile phone numbers called in the mountains that day:"

"Mobile phone number xxxxxxxx is turned off and has no signal."

"The records show that the last time it was connected to the Internet was 13 days ago, at 3:32 minutes and 18 seconds in the afternoon."

"This..." Lin Xinyi realized something:

The afternoon 13 days ago was the time when that call took place.

One of the people on the call at that time actually turned off his phone after that afternoon until now.

"I'm afraid this is the deceased's cell phone!"

"After killing her, the murderer must have taken her mobile phone away from the scene and disposed of it."

Lin Xinyi was even more certain that the two parties on this phone call were the murderer and the deceased in this case!

"What about the second mobile number?"

"This should be the murderer's mobile phone number——"

"Where is the murderer now?"

Noah’s Ark quickly sent a reply:

"The second mobile phone number is currently active, and the base station connected to this mobile phone number..."

"Mr. Lin, this is the base station you are using now."

"What?!" Lin Xinyi was shocked:

The murderer's cell phone is now using the same signal base station as him?

Doesn't this mean...

"Yes."

Noah’s Ark sent the conclusion directly via text message:
Chapter completed!