Episode 54:
The Gangnam Rooftop Murder: Medical Student Who Killed His Girlfriend and Played Victim

A couple in their twenties climbs to the rooftop of a fifteen-story building near Gangnam Station and shares a bottle of soju. He's smiling — but in his head, something far darker is already decided.

That same day, police rescued a man from the building's ledge first. The woman's body was found only afterward, in a blind corner of the rooftop.

The man they saved called himself an elite — a perfect scorer on Korea's national college exam, admitted to Yonsei Medical School. But the story behind that image was nothing like the one he sold in interviews.

The Man on the Ledge

On May 6, 2024, a bystander near Exit 9 of Gangnam Station reported a man standing on the edge of a fifteen-story rooftop. Rescuers barely pulled him back — he thrashed and kicked, but said almost nothing, not even his name.

At the station, he finally asked to hear his mother's voice, then grew calmer — calm enough that officers noticed the change. When he asked to retrieve a bag he'd left on the roof, an officer went up in his place. In a blind corner, they found drops of blood, then a young woman collapsed on the ground, already dead, stabbed more than twenty times.

A Marriage No One Approved

The victim was twenty-four-year-old Nam Su-ji, his middle school first love. They reconnected on Instagram in 2024, and just two months into dating, quietly filed for marriage without telling either family.

Choi was widely disliked on campus and increasingly isolated. Su-ji's family, alarmed by the sudden marriage, pushed for an annulment — and their lawyer advised her to cut contact entirely, since staying close would undercut any claim of coercion. Under pressure from both sides, Su-ji attempted suicide weeks before the murder. Because Choi was now her legal guardian, the hospital needed his consent for surgery — and he stalled, blocked her parents' numbers, and filed a police report accusing them of threats.

A Pattern of Control

While delaying that consent, Choi staged his own crises — a near-jump from a mountain, a hotel binge-drinking attempt that only left him hungover. Investigators would later conclude he had been gaslighting Su-ji for months, using a secretly filmed video to control her and swinging between declarations of love and threats.

When Su-ji's mother finally sent an ultimatum — an annulment lawsuit addressed directly to his medical school — Choi begged for one more chance, and the two spent three tense days at a hotel before he vanished at dawn on May 2nd. Su-ji reported him missing, fearing what he might do; police found him on a rooftop days later, seemingly attempting suicide again.

The Final Meeting

When Choi pushed to reconcile and Su-ji firmly refused, his tone shifted entirely. He raged that her family's lawsuit would reach his medical school and destroy everything he'd built. On May 6th, he asked to meet her one last time, at the rooftop they used to visit on dates.

As they shared soju, Choi steered the conversation to a nostalgic topic to get her absorbed in her phone, then quietly pulled a sashimi knife from his backpack. He stroked her hair, told her she was doing great — then pulled her head back and stabbed her neck ten times. When she didn't die as quickly as expected, he returned with the knife eleven more times, then stabbed both of her eyes and her forehead.

Phone forensics later showed searches for "how to kill with a knife" and "carotid artery murder" continuing even during what looked like an ordinary date. He had bought two sashimi knives and duct tape beforehand, and changed into prepared clothes afterward — undercutting his later claim that the killing was accidental.

Final Thoughts

After the murder, Choi climbed onto the rooftop railing — a move experts believe was calculated to support a later claim that his guilt was so overwhelming he wanted to die. Testimonies later emerged describing his relationships with men and comments suggesting he saw the marriage as a path to a wealthy father-in-law's financial backing for his own clinic.

His story shifted repeatedly at trial — accident, then premeditation, then mental impairment from anxiety — but a psychiatric evaluation found nothing wrong with him. In December 2024, the first trial sentenced him to 26 years, with the court citing his "potential to contribute to society." An appeal raised it to 30.

A perfect exam score and a coveted medical degree were never a measure of character. In thirty years, Choi Dong-uk returns to society — not as a promising doctor, but as a convicted murderer.