"A registered letter has arrived."

On July 10, a 30-year-old office worker living in Sejong, identified as A, received a phone call from an unknown number.

The man on the other end, who introduced himself as a court official, claimed that A was involved in a crime and asked whether A would prefer to receive the related documents at home or view them electronically.

Although flustered, A chose to view them electronically, not wanting to worry their parents.

When A clicked the link sent by the man, a document appearing to be from the prosecution office appeared, displaying a case number and A's name.

The document stated that a secret account had been opened in A's name without their knowledge and was being used for criminal activities.

Shortly after, a man claiming to be a prosecutor from the Seoul Central District Prosecutors' Office called to inform A of this, instructing them to purchase a used mobile phone, transfer their SIM card to it, and install a remote control application.

Intimidated, A followed the instructions.

When A could not provide an exact figure for their total assets, the prosecutor scolded A for "giving false statements" and pressured them by saying, "If you do not receive a summary indictment today, you will be taken to a detention center."

Frightened, A was told by the prosecutor to stay at a nearby hotel to "buy some time."

A ended up staying in that hotel room for a week without stepping outside.

From the first day of the call until leaving the room on July 16, A was forced to report their status every hour under the pretext of an investigation and was even coerced into writing statements of reason and letters of apology.

A explained that because the organization members interrogated them every hour, there was no room to suspect it was a scam.

A said they did not think to inform anyone around them for fear of worrying their parents.

As the fear intensified, a person claiming to be a Financial Supervisory Service (FSS) manager told A to "transfer the money to a safe account," leading A to send their entire life savings of 135.9 million won in ten separate transactions.

The person claiming to be an FSS manager was also a member of the voice phishing organization.

The organization members also lied to A, saying, "You need to catch the accomplice among the bank staff, so take out a loan. The debt will be restored once the investigation is over," which led A to take out loans totaling 87 million won.

Fortunately, the money was not stolen due to the bank's account suspension measures, but the organization members brainwashed A by claiming that if the bank made a verification call or blocked the account due to suspicious transactions, it was "also interference by the accomplice."

After a week of confinement, an anxious A checked the Korea Information System of Criminal Justice Services (KICS) app and only then realized it was a scam after confirming that the case number in the prosecution document they received was fake.

The individuals who claimed to be a court official, a prosecutor, and an FSS manager were all members of a voice phishing ring. A had fallen victim to a new "self-confinement" tactic where victims are lured to accommodations and prevented from leaving on their own.

This method psychologically pressures victims and cuts off contact with the outside world to prevent them from suspecting a voice phishing attempt.

A reported the damage to the Sejong Nambu Police Station on July 18, and an investigation is currently underway.

"When someone who has never been investigated is told by a 'prosecutor' that they will be taken to a detention center, they have no choice but to do as they are told," A said. "It is not just the particularly naive or those lacking financial knowledge who fall victim; anyone can become a victim if they are targeted at their most vulnerable moment."

The police have urged the public to be cautious, noting that voice phishing cases involving this "self-confinement" tactic have been occurring frequently.

In fact, last November, a person in their 40s who was deceived by a group impersonating the Supreme Prosecutors' Office and held captive for over ten days handed over 620 million won worth of gold bars. In February, another person in their 40s who had been trapped in a studio apartment in Daegu for a week was saved from transferring 1.8 billion won after police were dispatched following a report from an acquaintance.

A police official advised, "If you are instructed to cut off contact with family and acquaintances and stay in a specific place alone, please report it to the police immediately."