The prosecution is set to expand its investigation into the Unified Progressive Party after party members blocked investigators from searching its headquarters on Monday.

The Supreme Prosecutor’s Office on Tuesday pledged a thorough inquiry into law violations by the party including alleged vote-rigging, recent violence at a party meeting, and its obstruction of law enforcement.

“The party mobilized hundreds of its members to deter the seizure and search illegally. We will take stern action with all those involved in the violence and infringement of public authority,” the prosecution said in a statement.

The office said the UPP’s feud should no longer be left in the party’s hands.

“The party has failed to resolve the vote-rigging dispute and caused further social disturbance with factional conflicts and physical clashes during its central committee meeting. The situation required a full-scale investigation,” it said.

The prosecution also charged that the UPP tried to destroy some key evidence.

On Monday, investigators attempted to search the party’s headquarters. Due to fierce resistance from party members, they failed to enter the party building.

Another team of investigators seized three hard disks from the party’s computer server management company at 2 a.m. on Tuesday after 18 hours of tussling with resistant party officials.

During the process, four members were arrested on the scene.

The confiscated computers contained the information on the party’s disputed proportional representative primary process, as well as the party member register.

It turned out, however, that original hard disks had been replaced by new ones and that some of the information was deleted.

“We suspect that party officials intentionally manipulated the evidence to cover up for the primary irregularity,” said an official.

The authorities are to summon key party figures including former co-chair Lee Jung-hee and the disputed lawmakers-elect as early as this week, according to officials.

Kang Ki-kab, chief of the party’s interim decision-making body, claimed that the prosecution’s surprise raid was politically motivated.

“I cannot but question their intention in deciding to swoop in on our headquarters at such a crucial point in time,” Kang said in a radio interview on Tuesday.

Kang’s panel was about to announce on Monday the expulsion of Lee Seog-gi and Kim Jae-yeon as the two controversial proportional elects refused to step down despite the ultimatum delivered late last week.

The corresponding meeting was, however, delayed as most officials rushed to the party headquarters or the server management company to ward off the prosecutorial officials’ raiding attempts.

“The party will make its final announcement (on Lee and Kim) as early as tomorrow, regardless of the prosecution’s probe,” said the spokesperson.

The two figures recently transferred their membership from the party’s central headquarters to its Gyeonggi branch in an attempt to dodge defection, but this is not to affect the party’s jurisdiction over them, the spokesperson added.

Their expulsion may lead to the breakup of the five-month-old party as the former mainstreamer faction vetoed the decision of Kang’s committee.

Meanwhile, some observers blamed the prosecution’s high-handed probe and advocated the parties’ political freedom.

“Officials should first take peaceful procedures before forcing their way into the buildings,” said the People’s Solidarity for Participatory Democracy through a statement on Monday.

By Bae Hyun-jung (tellme@heraldcorp.com)