In many regards, the parliamentary special investigation into the Choi Soon-sil scandal is destined to be a failure.

The most disappointing part of the probe, which is to end Jan. 15, was the six rounds of hearings, during which lawmakers fell far short of pressing key figures to make substantial testimonies.

There are a combination of reasons why the parliamentary hearings failed to shed light on the scandal which has been shaking the nation for months.

Firstly, many of the key figures in the scandal refused to take the witness stand and the special parliamentary committee did not have any means to bring them to the stand.

There was little the committee could find without questioning people like Choi and former presidential aides An Chong-bum and Jeong Ho-seong. All in custody for their involvement in the influence-peddling and corruption scandal, the three cited health problems and ongoing trials as their reasons for shunning the hearings.

The committee could only issue warrants of accompanying to the three key figures and 33 more people who refused to testify. Only one of them, Choi’s niece Chang Si-ho, complied with it.

The committee members visited two detention centers to force the three to testify at “in-prison hearings.”

However, the attempt turned out to be mostly futile because they continued to be defiant. The committee members, divided into two groups, questioned Choi at the Seoul Detention House and both An and Jeong at the Nambu Detention House.

Unlike the previous five hearings which were broadcast live, the media were not allowed into the conference rooms where lawmakers met the three for 1 1/2 hours.

This lack of means to override the witnesses’ resistance must be addressed.

Under the current law, the National Assembly can ask the prosecution to charge those who refuse to take the witness stand with contempt of the parliament, which tends to carry a light punishment, such as fines.

The second problem with the hearings was that as usual, many lawmakers were not well prepared to grill the witnesses -- who included the nation’s top tycoons -- in a way that would make them admit their wrongdoings, disclose the truth or give clues that could help verify allegations and suspicions.

Of course, the hearings, most of which were nationally broadcast live until midnight, did achieve some results.

For instance, tycoons testified that they donated money to two foundations controlled by Choi under apparent duress, which could open the way for charging not only Choi but also Park and An with extortion and abuse of power.

The parliamentary committee also managed to question former Park aide Woo Byung-woo who had shunned the warrant of accompanying till the last minute, earning him the nickname “eel.”

Choi’s former associates -- some of whom are now estranged from their former boss -- also gave testimonies which support allegations that Choi peddled influence and sought personal benefits by exploiting her ties with Park.

But the committee members were also blocked time and time again by a parade of key witnesses who only said, “No” or “I don’t know” or “I don’t remember.”

Park’s former Chief of Staff Kim Ki-choon said he did not know Choi, but he had to retract the testimony after a lawmaker provided video footage from 2007 showing the two of them together.

Most lawmakers relied only on news reports and tipoffs -- and even rumors or speculations -- which made them ill-equipped to outwit witnesses who were apparently lying or hiding the truth. They even yelled and spewed words, some of which were the equivalent of “go to hell.”

In some sense, the high-handedness and rudeness of the parliamentary committee toward some witnesses provided some catharsis to the public which has been frustrated by the drawn-out scandal.

But real catharsis should have come from hearing what people had wanted to hear from those who played key roles in the shameful saga.

The hearings did little to uncover the truth, only adding to people’s frustration.

The National Assembly should work to reform the hearing system in order for it to become a more effective tool in probing cases of national importance.