The 63-year-old Cho was placed under arrest on Oct. 5 after a Seoul court approved his arrest warrant. Lee, who served as president from 2008 to 2013, was sentenced to 15 years in jail on the same day for corruption.

The NPA investigation team said it has confirmed the existence of about 12,800 Internet comments and Twitter posts written by the about 1,500 rank-and-file police officers, mostly mobilized from the NPA's information and security bureaus and spokesperson's office.

It then estimated the total number of manipulated comments to reach about 37,800 by taking seized NPA documents and various circumstances into consideration.

Cho and his subordinates are accused of attempting to fabricate pro-government and pro-police opinions on almost all major political, social and inter-Korean issues at that time, including the sinking of the Cheonan warship, the bombing of Yeonpyeong Island, foot-and-mouth disease, the death of North Korean leader Kim Jong-il, labor disputes at conglomerates, the parliamentary ratification of a free trade deal with the US and the conflict on the construction of a Jeju Island naval base.

They also tried to counter public opinions critical of Cho's various remarks and controversial policies by manipulating Internet and Twitter comments, the team noted.

The police officers mobilized by Cho operated under an informal organization and used offshore Internet protocol, aliases and names of their families and acquaintances to hide their identities, it said.

The team also found that the NPA's cyberspace investigation team had illegally monitored emails and Internet posts of seven anti-government groups and two netizens critical of government policies from December 2004 to November 2010 without obtaining relevant court warrants.

The team said it has asked prosecutors to indict a former chief of the NPA cyberspace investigation team and opened an investigation into two former officers of the military's Cyber Command on suspicion of handing over nicknames and other personal information of anti-government groups and individuals to the police. (Yonhap)