Prosecutors investigating the ruling party’s vote-buying scandal questioned National Assembly Speaker Park Hee-tae at his official residence on Sunday.

Park, who announced that he would step down on Feb. 13, is at the center of the alleged cash-for-votes scheme operated during the party’s leadership election in 2008, which he won.

The Seoul Central District Prosecutors’ Office’s investigation team arrived at Park’s residence at 9:25 a.m.

The team is focusing on whether Park gave instructions or had information regarding the attempted bribery of Rep. Koh Seung-duk of the Saenuri Party, previously the Grand National Party, before the party chairmanship vote on July 3, 2008.

Koh has alleged that he was given 3 million won ($2,660), which he turned down, and Park’s name card days before the election, by a man who the prosecution found to have worked for Park’s campaign at that time.

The investigators also questioned Park about his involvement in the bribery of lesser officials of the party.

Since Koh disclosed that there was an attempt to buy his support for Park in early January, investigations revealed a wider vote-buying scheme that led back to former presidential secretary Kim Hyo-jae.

An Byung-yong, head of a district chapter of the party, was allegedly instructed by Kim to hand over 20 million won to five members of district councils with instructions to bribe 30 party officials.

Investigations have shown that the money An distributed was obtained from Kim’s office when he was serving as head of the situation room at Park’s campaign for ruling party chairmanship.

In addition to the factors concerning the vote-buying scheme, the prosecutors are seeking to find out whether or not Park gave his campaign aides access to a loan account for 150 million won taken out under his name. The investigators will also seek answers regarding how Park spent the lawyer’s fee he received from Ramid Group before the party leadership election.

Park is the first National Assembly speaker questioned over allegations of bribery while in office since Kim Soo-han in 1997.

At the time, Kim was questioned by prosecutors over allegations that he received 50 million won from the Hanbo Group chairman. Kim was also questioned at his residence.

By Choi He-suk (cheesuk@heraldcorp.com)