The former chief of the nation’s main intelligence agency was questioned by prosecutors again over suspicions that he directed spy agents to influence public opinion ahead of last year’s presidential election, according to officials Tuesday.

Won Sei-hoon, who headed the National Intelligence Service for about four years until early this year, is under suspicion of intervening in domestic politics by ordering agents to post a slew of politically sensitive comments on the Internet in order to sway public opinion in favor of the ruling party candidate prior to the Dec. 19 election.

The law governing the status of NIS officials strictly prohibit them from intervening in domestic politics.

Won was allowed to return home late Monday night after hours of questioning, officials said.

It was the second time that Won, who headed the NIS under former President Lee Myung-bak, has undergone questioning in connection with the case.

During the first round of questioning, Won reportedly denied the charges against him, claiming that there was nothing illegal about the agency’s operations.

The former intelligence chief, who has been barred from leaving the country pending investigation, was questioned over whether he had given orders to the agents or been briefed about the agents’

alleged activities, they said.

He is also suspected of directing agents to actively promote major government projects such as the four-river refurbishment project and the South Korea-U.S. free trade agreement on the Internet.

Conservative ruling party candidate Park Geun-hye eventually won the race and took office in February as the country’s first female head of state. (Yonhap News)