A 15-year-old boy is being investigated for assaulting a senior citizen and causing his death.

The Muan Police Station in South Jeolla Province said it is investigating the middle school student for death resulting from violence, punishable by up to three years in prison. The suspect is accused of using fatal violence against a neighbor in his 70s at around 5:40 p.m. on Oct. 13.

The suspect told police that he punched the victim when he saw him arguing with his mother. The victim fell to the ground and hit his head on the floor, sustaining a critical injury.

He was treated at a nearby hospital but died four days later.

It has been reported that the two families had become well acquainted since the victim's family moved to the neighborhood seven years ago. But the two neighbors feuded over the suspect's family returning a gift for unspecified reasons, which led to the argument.

The victim's son alleged that none of the suspect's family came to apologize after the incident.

The police requested an arrest warrant for the suspect, which was declined by the court on grounds that he poses no flight risk. Officers have yet to decide whether to reapply for the arrest warrant.

The adolescent suspect is over the 14-or-under age limit that is immune to any criminal punishment, but is a minor and therefore subject to a relatively more lenient punishment than adults.