South Korean authorities arrested a marine Wednesday for allegedly helping his colleague steal weapons that he used in a shooting spree that killed four soldiers, the Defense Ministry said.
A 19-year-old marine corporal, surnamed Kim, went on a shooting rampage Monday at a Gwanghwa Island base, just south of the tense maritime border with North Korea. Military investigators later said that Kim was angry about being shunned and slighted and showed signs of mental illness before the shooting.
Early Wednesday, the military arrested one of Kim's marine colleagues _ a private first class only identified by his surname Jeong _ for allegedly helping him steal a rifle and bullets, a Defense Ministry official said on condition of anonymity, citing department rules.
The suspect told investigators he had plotted with Kim to "make a racket" and desert from their marine unit as a way of fighting against beating and abuse by superiors in the military, the official said.
Jeong said he decided against joining in Kim's shooting spree and denied that he helped Kim steal the weapons, the official said. Kim admitted to acting alone in the shooting spree but implicated Jeong in stealing the weapons, the official said.
Investigators said Tuesday that Kim had a "psychological problem" and referred to a note in which he was said to have lamented the state of his life. Defense Ministry officials said Kim wrote in a memo to an investigator that his fellow marines had treated him with little respect.
It wasn't immediately clear whether the two marines were beaten by superiors or abused by other marines before the shooting.
Kim _ who was reportedly drunk at the time of the shooting _ tried unsuccessfully to kill himself by detonating a grenade after the rampage. He is being treated and investigated at a military hospital, according to the Defense Ministry.
Monday's shooting was the worst in South Korea's military since 2005, when a soldier tossed a hand grenade and opened fire at a front-line army unit in a rampage that killed eight colleagues and injured several others. Pfc. Kim Dong-min told investigators he was enraged at superiors who verbally abused him.
The shootings have raised questions about the level of discipline in South Korea's military. All able-bodied South Korean men must serve about two years in the military under a conscription system aimed at countering aggression from North Korea.
Associated Press writer Sam Kim contributed to this report.