The prosecution has concluded that the cyber attack on the homepage of the National Election Commission on the day of the Oct. 26 Seoul mayoral by-election was jointly carried out by former aides to National Assembly Speaker Park Hee-tae and Rep. Choi Ku-sik.

According to the prosecution, the National Assembly speaker’s aide, surnamed Kim, and Rep. Choi’s aide, identified only as Gong, plotted the distributed denial-of-service attack and had it executed through Gong’s friend, a computer expert. Kim had paid 10 million won to the expert through Gong.

Prosecutors said they could not find any evidence that there was a mastermind behind Kim and Gong. They explained that the two suspects undertook the DDoS attack simply because they thought they could get promotions if their scheme panned out.

Their scheme was to paralyze the election watchdog’s website to make it difficult for voters to find the locations of their polling stations.

According to prosecutors, the two suspects thought this would lower the turnout of young voters who supported the liberal independent candidate, Park Won-soon, thus helping the ruling Grand National Party candidate, Na Kyung-won. National Assembly Speaker Park and Rep. Choi are both former GNP members.

The prosecution’s conclusion is hardly convincing. It fails to answer many important questions. For instance, prosecutors should have found out why the NEC had changed the locations of many polling stations for the by-election.

According to news reports, the NEC changed the locations of 572 of the 2,218 polling booths in Seoul. Many voters were unaware of that these voting places had changed. So they tried to access the NEC homepage to find out where their polling stations were located.

The DDoS attack would have been meaningless had there been no changes in voting booth locations. Hence it is important to find out who ordered the changes and for what reasons, and how the two suspects came to know about the changes.

If, as prosecutors say, the two suspects committed the cyber-attack to get promotion, someone must have promised to reward them if they succeeded. National Assembly Speaker Park and Rep. Choi have not been implicated.

Now, the only means available to get to the bottom of the affair is an investigation by an independent counsel. Given the grave nature of the problem, lawmakers should waste no time in appointing an independent counsel. Yet the trouble is independent counsels have thus far not been effective in tying up loose ends.