Security camera footage shows a man, in the red circle, forcing a boy underwater. Courtesy of Channel A

A man who dunked a 7-year-old boy's head underwater at a swimming pool is under investigation for alleged child abuse, according to Channel A, a Korean cable news channel, Wednesday.

The police in western Seoul's Mapo District handed the case over to the prosecution without detention on Monday, the news channel said.

The police allege the man in his 30s forced the boy's head underwater multiple times at a Han River park swimming pool on Aug. 3. Security camera footage shows the suspect grabbing the boy's head and dunking it in and out of the water.

The boy's sister, who was at the scene, tried to stop the man to no avail.

"The man told me to bring my parents. I tried to leave with my brother to get them, but he didn't let my brother go. Instead, he kept putting his head into the water," the sister was quoted as saying.

The boy's father reported the incident to the police, but the man was gone by the time they arrived.

Police reviewed the parking records of approximately 2,000 vehicles in nearby parking lots and examined all available security camera footage to identify him. It took 23 days to track him down.

The man told the police that he had lost his temper after his own child was splashed.

He sent a letter of apology to the victim's family, who responded by saying the apology wasn't sincere.