Three soldiers have been detained in an investigation into the apparent suicide of their junior comrade last week, military officials said Tuesday.
  

The incident took place last Thursday at around 5 a.m., when the private first class moved about 100 meters away from a guard post near the western border with North Korea, where he and his fellow soldier were on patrol duty.
  

The 20-year-old was killed at the scene as a grenade he was holding went off soon after he moved away from the guard post.
  

Military authorities presume that the private first class pulled out the grenade's arming pin himself, and they issued an arrest warrant for the three soldiers to investigate whether there had been bullying in the barracks.
  

It is the latest in a series of incidents that hit South Korea's military in recent years.
  

Last year, an Army sergeant who had been bullied by his comrades went on a shooting rampage near the border with North Korea, killing five and wounding seven others.
  

Assaults and abusive treatment of junior enlisted soldiers by their seniors in barracks have long been problems for South Korea's military, which relies on a conscription system.
  

All able-bodied South Korean men must carry out compulsory military service for about two years in a country facing threats from North Korea across the heavily fortified border. (Yonhap)