A soldier had killed himself at the Marine Corps Second Division near Seoul just a day before Monday’s shooting rampage at his division, military officials said Friday, as investigations continued into the case that killed four soldiers.

Authorities said they are investigating whether habitual bullying was rampant among marines at the division in Ganghwa, Gyeonggi Province, leading to the two tragedies.

According to the Ministry of National Defense and the Anseong Police Station, an unnamed 23-year-old private was found dead at a stairway of a commercial building while he was on a one-day holiday on July 3. Police concluded the young private had committed suicide.

The suicide was kept secret by the military, but became known to the public by his friends who posted the story on social network service Twitter.

According to their Twitter accounts, the deceased soldier dreaded his life in the army and had his collarbone broken by corporal punishment from his superiors, adding weight to speculation that harassment and bullying may have driven him toward suicide.

The Defense Ministry said the private had not mentioned any bullying in his suicide note. All funeral procedures have been completed, it said.

The private’s death was revealed just days after a 19-year-old corporal of the same division, identified as Kim, opened fire with a K-2 rifle, killing four soldiers. Kim claimed that he was neglected, suppressed and isolated among his team.

A military court on Friday ordered the arrest of Private Chung, who is suspected of acting as Kim’s accomplice, and two of his superiors for mismanagement of the team.

“We will root out evil practice in the barracks, even if they are traditions,” Commander Yoo Nak-jun said at a high-ranking officials’ meeting on Friday morning.

Yoo had admitted the previous day that the culture at marine camps is “a decade behind” that of South Korea’s other armed forces.

“I’ll see to it that from now on, there will be innovation, harmony and comradeship in the barracks,” he said.

By Bae Ji-sook (baejisook@heraldcorp.com)