Gyeonggi Province Governor Nam Kyung-pil's son, who is a corporal in the Army, abused subordinates more severely than previously believed.
Military authorities are accused of trying to downplay the crimes of the 23-year-old, who serves with a unit in Cheorwon, Gangwon Province, 88 km south of Seoul.
A spokesman for the Center for Military Human Rights Korea told reporters on Tuesday, "We've confirmed through the military's internal investigation records that corporal Nam abused his subordinates more severely than was previously announced."
"According to the records, Nam confessed he rubbed his penis against the buttocks of one of his subordinates, who is a private first class, and sexually molested him in the barracks on several occasions late last month and early this month," the spokesman added.
Nam also hit the private in the face or assaulted him 50 times on seven occasions during sentinel duty.
The military earlier said the corporal was only being investigated for one assault and one possible count of sexual abuse, which it quoted him as describing as "a joke."
But the full extent of the charges was revealed in an email sent to the center by a senior Army officer on condition of anonymity. The whistleblower reportedly handed the center the report containing Nam's own confession.
The spokesman said, "Despite the seriousness of Nam's crimes, the report indicates that the military police decided to investigate him without arrest."
An hour before the press conference, military police asked a military court for an arrest warrant for Nam, prompting speculation that they only acted because they knew about the leak.
But the court rejected the request on the grounds that Nam is not a flight risk or likely to destroy evidence.
"Military authorities covered up several major offenses Nam committed," said Lim Tae-hoon, the chief of the center, said. "The military should immediately dismiss the commander, the military police chief and investigators in charge, who apparently wanted to go easy on Corporal Nam and find out if his father tried to meddle with the investigation."
The Army denies a cover-up.
Meanwhile, it belatedly emerged that Nam divorced his wife early this month. Nam, who was elected governor of Gyeonggi Province in early June, has often been cited as a future presidential candidate, but the scandals have dealt a severe blow to his political ambitions.