Congressional investigators in the South Korean influence-buying probe said yesterday they are looking into the circumstances surrounding a guilty plea quietly made earlier this year by one of the major witnesses in the investigation that he smuggled $75,000 in cash into the U.S.

The witness, former Korean Central Intelligence Agency chief Kim Hyung Wook, pleaded guilty to the smuggling charge in U.S. District Court in New York City and was given a one-year suspended sentence March 15.

Kim, who lives in a well-to-do New Jersey suburb, testified last year that he was unemployed. He appeared in connection with South Korean influence-buying allegations before two House committees last year and also gave testimony to a grand jury here that was looking into the allegations.

At the time of his testimony last June Kim was denounced by Seoul goverment officials who said he had been deeply involved in official corruption when he headed the KCIA and in other official positions in South Korea.

According to Julie Moon, a correspondent for U.S. Asian News. U.S. Customs Service sources said Kim was arrested Jan. 18 of this year after a custom agent spotted him walking oddly through Kennedy International Airport in New York. He was found to be carrying $75,000 in cash taped to his legs.

A spokesman for the House International organizations subcommittee, which has been into South Korean influence-buying allegations said yesterday that the subcommittee was aware of Kims guilty plea to the smuggling charge.

The spokesman said some subcommittee members feared the smuggling conviction could cast doubts on Kim's credibility as one of the subcommittee's major witnesses in the inquiry. "We have spoken to him about it and we are continuing to take a long hard look at the matter," he said.

Sources at the House Committee on Standards of Official Conduct, which has also had Kim as a witness in its probe into the South Korean influence-buying charges, said yesterday they did not feel the smuggling conviction reflected on Kim's testimony.

Kim has also appeared for the Justice Department before a grand jury here looking into the influence-buying charges. Justice officials connected with the investigation could not be reached immediately for comment yesterday.