A South Korean Army colonel was indicted Wednesday for obstructing the military's investigation into the alleged involvement of its cyber warfare unit in domestic politics, the defense ministry said.
The arrested officer, identified only by his surname Kim, impeded or manipulated the military police's probe while serving as chief of the ministry's criminal investigation team from 2013-2014, according to a task force.
He also falsified an official document on the results of the probe to be released to the media, it added.
The ministry launched the task force last October to look into the widespread allegations that some military units - particularly, the Cyber Command and the Defense Security Command - were mobilized for political purposes under the former conservative administrations of Lee Myung-bak and Park Geun-hye.
The Cyber Command was launched in 2010 with a mission to counter North Korea's hacking attempts and other cyberattacks.
In its early years, however, some of its troops and agents were allegedly mobilized to support the spread of messages sympathetic to government policies and critical of opposition blocs, especially ahead of the 2012 presidential elections.
The task force added that the Defense Security Command was found to have started a secret operation to help control civilian opinions in cyberspace around June 2008.
"So far, it has been confirmed that more than 500 members of the command were involved in cyber reply activities between early 2009 and early 2013 ," it said.
They posted politically-motivated replies to Internet news on such politically sensitive issues as the four rivers project, the construction of a Jeju naval base, the South Korea-US free trade agreement and the deadly sinking of the Cheonan corvette near the Yellow Sea border with North Korea, the task force added.