The main opposition party filed charges Thursday against the nation's top spy agency and its former chiefs, accusing them of allegedly wiretapping government critics for years, and then allegedly trying to destroy related evidence after media reports exposed the scandal.
But the liberal New Politics Alliance for Democracy refrained from filing charges against incumbent National Intelligence Service head Lee Byung-ho, and vowed to take additional legal moves if the party found further evidence of foul play by the NIS.
"(Lee) has been in office too short a time to have extensive knowledge (of the allegations)," said an aide to NPAD Rep. Song Ho-chang, a member of the NPAD's in-house special committee investigating the scandal.
"Nam Jae-jun and Won Sei-hoon are more likely to be linked to these allegations," the aide added. Nam served as NIS director from 2013 to May last year. Won served as chief from 2009 to 2013. NPAD officials suspect the alleged wiretappings began around 2010.
Ruling bloc officials called the opposition's move "most irresponsible," saying that the opposition's demands that the NIS reveal related records would only benefit North Korea, considered by Seoul officials to be the South's main national security threat.
"This truth game will only benefit North Korea," ruling Saenuri Party Rep. Suh Chung-won said, adding that NIS records must be kept as "unpublic" as possible for security reasons.
"Considering our national security situation, (Thursday's filing) is utterly irresponsible," Saenuri Party spokesman Rep. Kim Young-woo said, urging NPAD Rep. Ahn Cheol-soo to retrieve the bill of indictment.
Ahn, a software mogul-turned-politician, heads the NPAD panel probing the scandal.
Thursday's filing comes amid an escalating public blame game between the NIS and its distrusting critics, led by senior main opposition party officials.
Local reports and the opposition accuse the NIS of bugging critics of the Lee Myung-bak and Park Geun-hye administrations using malware purchased from Hacking Team, an Italian malware surveillance vendor.
The NIS admits to the purchase but denies illegal use of the malware. An NIS agent was found dead last week in an apparent suicide, adding another twist to the ongoing scandal.
The opposition suspects that the NIS could have covered-up the death as a suicide, citing closed-circuit television recordings showing that the colour of the dead agent's car registration plate appeared different from the earlier hours of the day and when police found the agent's body.
Police officials denied tampering with the car, saying that the CCTV images colour appeared different due to "optical illusions" caused by differences in the cameras' angles.
Police later Thursday added that authorities had conducted experiments using the same car model of that of the dead agent, demonstrating that the CCTVs produced images with different colors.