Four military personnel were arrested this month on charges of hacking into e-mails of a professor at Chosun University in the southeastern city of Gwangju, military investigators said Monday.

The Criminal Investigation Command under the Defense Ministry said that security operatives broke into the e-mails of Gi Gwang-seo, political science professor at the university, and downloaded nearly 700 documents in early September.

This incident has drawn attention as speculation has risen that military security operatives have illegally monitored civilians.

Critics said that military authorities did not make serious efforts to dig into the case, allowing some suspects to destroy their evidence before their arrest this month.

The CIC said that they apparently hacked into his e-mails as the military has faced public criticism for “sloppy security management.”

In May, a senior professor at the Air Force University was alleged to have leaked military secrets. In the same month, a person with a record of contravening the National Security Law was found to have contacted the electronic database of the Joint Chiefs of Staff.

The CIC said that amid the criticism, the security operatives found that the professor who previously violated the National Security Law had frequently contacted military officers and lectured at a military educational facility in Jangseong, South Jeolla Province.

The police inquiry opened in early September after the professor reported to a police cyber investigation team that some of his online documents had been hacked.

According to officials, an Army warrant officer at the Defense Security Command in Gwangju asked a military civilian worker, surnamed Kim, to collect online materials concerning the professor in late August.

Kim then asked his close friend, surnamed Han, in Seoul, also working for the DSC, to help him access the professor’s email. Along with Han and a sergeant first class, Kim’s colleague in Gwangju, Kim succeeded in downloading the professor’s documents on Sept. 1 and 2.

“Han asked his colleagues to collect basic materials just for reporting (to higher authorities). But they apparently went overboard during the process of collecting the materials in violation of the law,” Lieut. Col. Kwon Tae-seok, senior CIC staff in charge, told reporters.

Kwon also said that no other military staff were found to have been engaged in the hacking incident.

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