Main opposition presidential candidate Yoon Seok-youl is unlikely to face indictment over allegations the prosecution colluded with the opposition party to attempt to investigate pro-government figures when he was prosecutor-general, observers said Friday.

The investigation into the alleged collusion floundered after the Seoul Central District Court rejected an arrest warrant for Son Jun-sung, a prosecutor accused of conspiring with the People Power Party, for the second time Thursday.

Son's arrest had been considered a key bellwether of whether the Corruption Investigation Office for High-ranking Officials (CIO) would be able to expand the investigation to charge Yoon, as Son was directly under him at the time.

Now that the CIO failed to prove Son's charges, Yoon's indictment is unlikely, observers said.

The Seoul Central District Court ruled the CIO failed to make a sufficient case for an arrest. An earlier arrest warrant request for Son was struck down in October for similar reasons.

The CIO is expected to wrap up the political meddling case by indicting Son without detention.

Kim Keon-hee, Yoon's wife, who was accused of being involved in a separate stock manipulation case of Deutsch Motors Inc., a BMW car dealer in South Korea, is also expected to be cleared of charges by the prosecution amid an apparent lack of damning evidence or statements, according to observers. (Yonhap)