The Marine who went on a shooting rampage Monday, killing four fellow soldiers, had been treated like an outcast on his base on Ganghwa Island, military officials said Tuesday.

The 19-year-old corporal, identified only by his surname Kim, said in writing, “I feel a lot of pain. I want to die. The practices of beating and ostracizing a soldier should disappear.”

Kim suffered injuries after detonating a grenade, intending to commit suicide at the warehouse near a barrack of the Marine Second Division off the west coast, where the shooting took place.

Kim pointed to a long-standing tradition in the Marine Corps, called “gisuyeoloi.” Under the tradition, fellow soldiers make a maladjusted member an outcast, and soldiers with a lower rank do not treat him as their senior.

“They do not treat me as their senior soldier. ‘Gisuyeloi’ should be stamped out,” he wrote.

Marines in Korea have long prided themselves on being part of their corps even after a discharge. Being designated an outcast is an extremely disgraceful experience for any Marine.

Military investigators are now putting considerable emphasis on “personal psychological problems” as a primary cause for the shooting rampage.

Announcing an interim investigation result, they also said that Kim has been classified as a “soldier that needs special attention” as there were “some problems” in his attitude and speaking.

Investigators found that Kim apparently drank alcohol before he fired some 12-13 shots with his K-2 rifle at his fellow soldiers.

The probe could not proceed quickly as Kim was unable to speak due to the injuries he sustained after detonating the grenade following the rampage, which took place between 11:40-11:50 a.m.

The shooting incident triggered sharp public criticism as it was revealed that the live ammunition was not kept safely at the base. At the time of the incident, the storage facility was left open with the non-commissioned officer in charge of it having stepped out

“Corporal Kim stole some 75 bullets, two blanks and one grenade from a temporary ammunition storage facility at around 10 a.m.-10:20 a.m.,” Navy Capt. Kwon Young-jae, an investigation chief, told reporters.

“The ammunitions facility was not properly taken care of. There should be two soldiers holding two separate keys to it, but we found that only one was managing it.”

Investigators also said that Kim shot the rifle in a single-shot mode rather than firing multiple shots at a time.

“The rifle we found at the scene was in a single-shot mode. After examining the bodies of the dead soldiers, there were no signs of multiple shots fired at a time from the rifle,” Kwon said.

Authorities also found a three-page memo and what appears to be a suicide note in his cabinet. Officials said, however, they have yet to verify whether the suicide note was written by him.

According to military sources, he said in the memo, “I hate myself. There are many who want to change me. My recalcitrant personality shown to teachers during my school days appears to come back. I hate myself grimacing and swearing when seniors speak.”

Some reports also said that since he joined the Marine unit last September, he had been given a special attention as the results of the personality test at a military training center suggested he had symptoms of nervousness, personality problems and schizophrenia.

Meanwhile, the Marine Corps has decided not to conduct an autopsy on the dead soldiers according to the wishes of the bereaved families. Some 70 relatives of the deceased soldiers are now at a military hospital in Seongnam, Gyeonggi Province where their bodies are laid.

A staff sergeant, two corporals and a lance corporal were killed in the shooting. Kim and another private first class who was injured in the incident are not in critical condition, officials said.

By Song Sang-ho (sshluck@heraldcorp.com)