SEOUL, South Korea -- The scandal shaking up South Korea's main spy agency is not cloak-and-dagger stuff, but the kind of low-grade trickery anyone with an Internet connection could pull off. And the target was not Seoul's opaque rival to the north, but the country's own people.
Internet postings ostensibly from ordinary South Koreans, but actually from National Intelligence Service agents, allegedly boosted President Park Geun-hye while she was running for the job as the ruling party's nominee. She was reportedly dubbed "the best," while her opponent, in a play on his name, was called "criminal."
A police investigation conducted before the December election found no wrongdoing, but now police say at least two agents violated the law and the original investigation is itself being examined.
Dozens of Internet comments, or more, may not have affected an election that Park won by a million votes, but they have damaged public trust in a spy agency that already had a dubious record.
The agency was founded in 1961 by Park's father, longtime dictator Park Chung-hee. Agents detained, tortured and even allegedly killed his political opponents. After Park was killed in 1979 -- by his spy chief, ironically enough -- other abuses occurred under his successors.
In recent years, however, criticism of the NIS has centered on what it has failed to do - namely, come up with much intelligence about North Korea. It learned about Kim Jong Il's death in December 2011 two days after it occurred, when Pyongyang's state TV announced it.
The Internet comments scandal captured headlines in South Korean media late last month, when state prosecutors summoned the agency's former director, Won Sei-hoon, and raided its Seoul headquarters. Reports recalled the unfortunate fates of predecessors who ended up being arrested, imprisoned or even killed.
"The prosecution will mobilize all its capabilities to swiftly and thoroughly get the truth of the case," Prosecutor-general Chae Dong-Wook said in a meeting with top prosecution officials Tuesday, according to his office. "This case should be investigated in a way not to have any lingering suspicion."
The scandal flared about one week before the Dec. 19 election. Liberal opposition members camped outside the apartment of an NIS officer allegedly involved in illicit online campaigning, based on a tip from another agent. The officer locked herself in the apartment for two days, then came out -- wearing a mask and a baseball cap to conceal her identity -- to let police confiscate her computers.
The incident triggered a last-minute election debate over whether the NIS illegally engaged in politics, or whether the opposition party harassed an innocent woman.
Three days before the election, police announced the results of their initial investigation by clearing the officer of any wrongdoing, giving Park's camp a source of criticism on her main rival, Democratic Party candidate Moon Jae-in.
Kwon Eun Hee, a police officer who headed the initial investigation, recently told The Associated Press and other media that her bosses inappropriately interfered in the probe by pressing her team to drastically decrease the number of search words they would use in analyzing the NIS officer's computer hard disk, in an apparent effort to announce the investigation results before the presidential election.
Top police officers have denied Kwon's claim, saying there was no attempt to cover up the truth about the case, according to the National Police Agency.
Police said last month they've found that at least two agents and an ordinary citizen, who was allegedly in collusion with them, posted 100 comments on at least two websites in violation of a law banning the NIS from engaging in domestic politics. Police subsequently requested that prosecutors indict all three people, one of whom is the agent the opposition had accused before the election.
One of the websites is the online forum "Today Humor," which had more than 950,000 unique visitors last month, according to Nielsen KoreanClick.
Police found that the agents didn't violate the election law because they weren't influential enough to sway the election's outcome, as they only supported government policies and projects rather than directly criticizing Moon.
One of the comments disclosed by police praised Park's predecessor and fellow ruling party member Lee Myung-bak for making many overseas trips: "President Lee Myung-bak will make a five-day trip to Indonesia and Thailand from tomorrow. This will be his 48th overseas trip and it is overwhelmingly the largest-ever (among South Korean presidents). He is really great."
Democratic Party officials agreed the comments didn't have straightforward, bold criticism on Moon but rather tried to derogate him and support Park by slightly tweaking the spelling of their names. For instance, in their postings they called Moon Jae-in "Moon Joein," which means "Moon, the criminal," while calling Park Geun-hye "Geun-hye, jjang," which means "Geun-hye, the best," according to party officials.
The NIS has defended itself, saying the two agents were only engaged in missions to cope with North Korea's cyberwarfare by posting comments countering messages praising the North's system and spreading groundless rumors about South Korean government policies.
Opposition lawmakers and activists suspect a broader, systemic operation than has been revealed so far, involving a far larger number of NIS agents.
A nonprofit organization called Lawyers for a Democratic Society conducted an independent investigation and said NIS agents also tried to vote down posts unfavorable to Park at Today Humor, which selects the daily top comments based on votes from users.
At least four individuals created 73 IDs at the Today Humor forum since August and cast more than 1,100 votes against the posts that depicted Park unfavorably, according to Park Jumin, an attorney of the organization. They collectively expressed opposition to the posts that depicted Moon favorably, he said.
Critics attacked what they see as an attempt to affect the election, and said the work had little to do with the spy agency's job.
"How much effort had been needed to make the spy agency commit itself to its main duty? What's happening now is like having backtracked in those efforts," said Lee Cheol-hee, head of the private Doomun Political Strategy Institute in Seoul. "It's a very serious matter."
"They did something that they shouldn't do .... while little achievement on one of its main duties - North Korea intelligence - are seen," said analyst Paik Hak-soon at Sejong Institute in South Korea. "Unless it places its priority on something, that cannot help being neglected."
The NIS has been criticized for failing to learn of Kim Jong Il's death before Pyongyang announced, and for failing to predict the North Korean shelling of a South Korean island that killed four people in 2010. According to a lawmaker who attended a closed door parliamentary committee meeting, Won told lawmakers his agency had intercepted North Korean communication indicating such an attack two months before the strike, but he thought it was routine rhetoric.
In May 2011, the NIS reportedly gave an inaccurate briefing to the presidential Blue House saying Kim's son Kim Jong Un had taken a trip to China, then was slow in correcting itself to say it was Kim Jong Il making the trip, even after South Korean media picked up on the story. Kim Jong Un is North Korea's current leader.
Critics say a key reason for those alleged intelligence blunders was that former President Lee gave top NIS posts to close associates who had little intelligence expertise. Won, the former director, spent most of his career in Seoul city government.
In a recent statement, the NIS said no intelligence agency in the world knew about Kim Jong Il's death before the North's state media announced it, and that the deaths of Soviet dictator Josef Stalin and Chinese leader Mao Zedong became known in similar fashion. In the case of Kim Jong Il's 2011 China trip, the agency said it was aware that the senior Kim was solely traveling, but that it didn't do anything for about the inaccurate reports because it had to protect its source of the information and was considering ties with China.
Park Geun-hye has not been accused of wrongdoing in the Internet postings scandal.
Her father was not her only predecessor to use the spy agency to meddle in politics.
Under the government of President Kim Dae-jung, the Nobel Peace Prize winner and a longtime opposition leader who was kidnapped by the elder Park's agents in 1973, spy agents wiretapped the phone conversations of high-ranking officials. Two of Kim's spy masters were later convicted over the scandal and received suspended prison terms.
Some South Korean intelligence chiefs suffered worse fates. Park Chung-hee's former spy director Kim Hyung-wook, who had criticized his authoritarian leadership, mysteriously disappeared in France in 1979. In 2005, a government fact-finding commission said he had been assassinated by Eastern Europeans hired by the spy agency. Kim Jae-kyu, the spy chief who gunned down Park Chung-hee during an October 1979 drinking party, was hanged the following year.
-- AP writer Youkyung Lee contributed to this report.