Prosecutors are expected to grill former police chief Cho Hyun-oh, who was arrested last week over allegations that he masterminded online public opinion-rigging in favor of the Lee Myung-bak government in 2010-2012.

A special investigation team under the National Police Agency put their former boss behind bars on Oct. 5 upon a court warrant, the first time ever a former National Police Agency commissioner has been held in detention at a police station.

Cho faces charges of abuse of authority and obstructing others’ exercise of rights for allegedly mobilizing some 1,500 police officers in security, intelligence and public relations departments under his command to write tens of thousands of pro-government comments on major current issues on the Internet from January 2010 to April 2012 during his time as the chief of the Seoul Metropolitan Agency and the NPA.

The investigators summoned Cho as a suspect and questioned him twice before getting a court warrant to jail him.

Cho allegedly made the police officers post comments on online news articles, on Internet forums and on Twitter about issues such as the North Korea’s torpedo attack of the South Korean naval ship Cheonan, foot-and-mouth disease, unionized workers of Hanjin Heavy Industries & Construction, and the Korea-US free trade agreement.

Investigators suspect that Cho attempted to manipulate public opinion by instructing his officers to use foreign IP addresses and other private Internet access points to disguise themselves as ordinary civilians posting comments online.

Police are soon to announce the results of their investigation into Cho.

By Kim So-hyun (sophie@heraldcorp.com)