A New Investigative Technique Tackling Rising Dark Part-Time Job Cases

The Reality of the Rapidly Increasing Number of Dark Work Cases

Since August of this year, there have been a series of robberies mainly in the Tokyo metropolitan area, including Tokyo, Kanagawa, and Saitama prefectures. In each case, several young men broke into a house by breaking the window glass, violently attacked the occupants, and robbed them of their money and goods. On October 16, a victim was found in a house in Aoba Ward, Yokohama City. The police authorities are investigating the case as being committed by an “anonymous and fluid crime group” (a.k.a. Tokuryu), which commits repeated crimes in a fluid manner through highly anonymous SNS.

The main feature of the incident is that the group solicited part-time jobs on social networking services with posts such as “white-collar jobs” and “high rewards,” as if they guaranteed high salaries for safe work. The young people who applied for the jobs were asked to install the highly anonymous communication application “Signal” on their smartphones and send information such as their driver’s license, ID card, and other photos, as well as their parents’ home address and family structure. The same pattern is followed by an “instructor” who has the personal information of the youths and forces them to carry out the robberies.

If the youths hesitated to commit the robbery, the instructor would threaten them with such phrases as, “Do you care what happens to your family? Another characteristic of the criminal group is that the instructor’s criminal group stays in a safe zone and never reveals themselves.

The first incident suspected to be related occurred in late August in Saitama City, Saitama Prefecture, and on October 18, the Metropolitan Police Department and the Kanagawa, Chiba, and Saitama prefectural police established a joint investigation headquarters for 14 incidents up to the robbery and assault incident in Ichikawa City, Chiba Prefecture, which occurred in mid-October. Kazuhito Shinka, chief of the Metropolitan Police Department, said,

“We need to use all the resources of the Japanese police force to cut out the bad guys behind these cases at the earliest possible stage, and to clarify the realities of the criminal groups and the full scope of the cases,” he emphasized.

He emphasized, “We need to use the full power of the Japanese police to quickly cut out the bad guys behind the crime and find out the real situation of the criminal group and the full scope of the case.

Not only do the perpetrators not get paid, but more than 30 of them have been arrested so far. The common denominator is that they are used and discarded like pawns. There are other cases that are suspected to be related to this case, and the total number of cases is believed to be more than 20.

Evolving ‘Digital Forensics’

A senior police investigator noted , “The form of the crime is the same as the ‘Ralphie case. This is the second Rufi case. The senior police official emphasized that “digital forensics” is the key to the future investigation.

Digital forensics” refers to “electronic forensics,” a technology that reconstructs erased or deleted digital data, such as case instructions, and uses it as objective evidence in an investigation. It is a method of collecting and analyzing evidence that remains in digital space, just as DNA-related materials such as hair, fingerprints, and footprints are collected as evidence at crime scenes in real space.

The method is not easy to generalize, as it varies from device to device and condition to condition, but an example is as follows.

First, a special screening application is used on the seized smartphone to determine if there is data that can be recovered and to what extent. From there, a special AI is used to extract candidate passwords. The password unlocks the automatic memory deletion function in the app. However, since the password is only a candidate and cannot be identified, the possibility of failure is higher. If successfully unlocked, the information recorded on the phone can be collected.

They say that they get clues on the basis of these investigations, but even so, the investigators say, “There is no example of 100% complete recovery. We will multiply fragmentary evidence from a number of smartphones and determine the specific instructions and sender,” he said. The investigative official further intensified his tone as follows.

In the Ralphie case, the main suspect, defendant Yuki Watanabe, and others emerged on the investigation line by connecting information such as call logs to the Philippines. From there, we used special technology to unlock the smartphones of the Watanabe defendants and others, analyzed the information, and uncovered the instructions given to the perpetrators, which led to the full investigation of the case. The investigation of the current case also depends on whether the analysis of the arrested perpetrators’ smartphones can be used to trace the information back to the directing officers and others.

A senior member of a designated crime syndicate based in the Tokyo metropolitan area commented on the series of robberies, saying, “It may seem strange for us to make such a statement from our perspective.

The Yokohama case was a robbery-homicide. The only penalty for robbery-murder is death or life imprisonment. The young people who were beaten up probably don’t know how serious the crime is. We know better and will not cross such a dangerous bridge. Murder on top of robbery will definitely ruin your life. If someone doesn’t teach them a lesson, there will be more cases like this.”

The cost of being lured by the sweet words of “high rewards” and applying for a black market job with an easy mind is too great.