Marine Corps division commander Im Seong-keun’s three-year prison sentence upheld, just over three years after Corporal Chae died on duty

[Financial News] Im Seong-keun, former commander of the Republic of Korea Marine Corps 1st Division, was sentenced to three years in prison for the fatal incident in which the late Corporal Chae Soo-geun died on duty. The sentence was finalized 1,196 days after the accident on July 19, 2023.
The Supreme Court’s First Division, with Justice Shin Sook-hee as the justice in charge of the case, on the 27th dismissed appeals by both former division commander Im and the special prosecutor team investigating Corporal Chae’s case, led by Special Prosecutor Lee Myung-hyun. Park Sang-hyun, former commander of the 7th Brigade of the Marine Corps 1st Division, and Choi Jin-gyu, former commander of the 11th Artillery Battalion in the 1st Division’s Artillery Brigade, each had their 18-month prison terms upheld. Jang, former commander of the headquarters company of the 7th Artillery Battalion, had an eight-month prison term suspended for two years upheld. A 10-month prison term for former 7th Artillery Battalion commander Yongmin Lee, whose sentence was appealed by neither the special prosecutor team nor Lee himself, had already been finalized.
The accident occurred at around 9:01 a.m. on July 19, 2023, near Bomun Bridge in Yecheon County, North Gyeongsang Province. While Marines from the headquarters company of the 7th Artillery Battalion were searching for a missing person by probing the riverbed with shovels, the sandy riverbed collapsed and swept Corporal Chae into the fast-moving current. He was found in cardiac arrest at around 11 p.m. that day and died early the next morning. Another service member who fell into the water with him was rescued but diagnosed with post-traumatic stress disorder.
The central issue was whether multiple commanders in the chain of command could be held jointly responsible for a single accident—in other words, whether joint principal liability for a negligent offense applied. Under this legal doctrine, when multiple people cause an outcome through shared negligence, each can be punished as a principal offender. The first- and second-instance courts found joint negligence by former division commander Im, former brigade commander Park and former battalion commander Choi, and the Supreme Court upheld that finding. The court said, “The lower court did not err in its interpretation of the legal principles concerning the establishment of the offense of occupational negligence resulting in death or injury, joint principal liability for negligent offenses, or related matters.”
The court found joint negligence in the fact that the underwater search was conducted without life jackets or safety ropes, and that the areas where personnel could enter the water were not clearly explained. It found that Im’s emphasis on an aggressive search and order to secure chest waders at a video conference on the night of July 18, the day before the accident, led to the underwater search. At the meeting, he said, “You need to go down, push through the brush, and probe as you search.” Park, as head of the 2nd Quick Maneuver Division, directed operations at the scene and pressured the troops to continue searching. Choi was found to have conveyed instructions referring to “entering the water up to waist depth” without explicit approval from higher headquarters.
The scope of the guilty findings for violating orders was narrowed. At the time of the accident, operational control had been transferred from the commander of the Marine Corps 1st Division to the commander of the Army’s 50th Infantry Division under a fragmentary order. The special prosecutor team identified eight acts by former division commander Im as violations of orders, but his visit to the on-site command post, troop inspections and instructions for a checkerboard-pattern search, among other acts, were found not guilty in the reasoning of the judgment from the first trial onward. The rationale was that even after operational control had been transferred, authority over administration, discipline and logistics remained reserved to the commander of the original unit. The charge that Im ordered the operation to continue despite a withdrawal directive was found guilty at trial but overturned on appeal. Ultimately, the only part that remained as a violation-of-orders charge was his remarks at the video conference. A reasoned acquittal is when the court states in its reasoning, rather than in the operative part of its ruling, that a defendant is not guilty; it is used when only some of the allegations grouped under a single offense are acquitted.
Some of the special prosecutor team’s arguments were rejected. The court did not accept the claim that Im violated his duty of care by keeping former brigade commander Park at his side all day on the first day of the operation, thereby creating a gap in command. It also rejected the claim that Choi had a duty to manage risks involving another artillery battalion that was not under his command.
In November 2025, the special prosecutor team indicted former division commander Im and others and sought a five-year prison sentence for Im. The first-instance ruling was handed down this past May, and the second-instance ruling this past August. The appeals court said the commanders had neglected their duty to strictly control entry into the water despite inadequate safety equipment, resulting in the death of a 20-year-old corporal who was four months into his military service. It noted that the incident could have become a major accident if the other service members had also been unable to escape on their own.
[email protected] Kim Dong-kyu Reporter