On March 12, 1948 the Jeju Sinbo (제주신보), a local newspaper, reported that a young man named Kim Yongcheol (김용철) had died while in police custody. The police for their part insisted that he had become ill and died from that. However, those that had seen Kim Yongcheol's body stated that he had bruises all over his body making the police's story lose credibility. A witness also would later testify to the media that the police had Kim Yongcheol hung up by the heels and beaten with clubs.

Even the autopsy was a bit odd. That is because it had to be performed twice. During the first autopsy the police interfered in the process. It took the American advisor from the CIC (Counter Intelligence Corps) to order a second autopsy for it to be done properly. Dr. Jang Siyeong (장시영), who performed the autopsy, concluded that Kim Yongcheol had died from a cerebral hemorrhage (bleeding in the brain) that was caused by external blows. This led to the imprisonment of all five police officers in the Jocheon police box.

References

The National Committee for Investigation of the Truth about the Jeju April 3 Incident - "The Jeju 4.3 Incident Investigation Report" (downloadable here in English)