The nation's top court on Friday acquitted a former lawmaker and popular online show co-host of charges that he slandered eight state prosecutors who investigated an alleged investment scam involving former President Lee Myung-bak.

Lee was at the center of a case widely known as the "BBK scandal" named after a firm set up by him and his convicted former business partner, Kim Kyoung-joon, in 2000. The scandal broke at the height of the 2007 presidential race when the Korean-American businessman claimed Lee was involved in the investment scam and stock manipulation.

Prosecutors, however, cleared Lee of wrongdoing shortly before the election. Lee, who was a leading conservative-bloc presidential candidate at the time, eventually won the election by a landslide despite the speculation.

The former lawmaker, Chung Bong-ju, claimed that a crucial piece of evidence was omitted during the prosecution probe, prompting the eight prosecutors to file a defamation lawsuit against Chung for spreading false information.

Upholding a lower-court verdict, the Supreme Court said, "It is a reasonable activity of a lawmaker to supervise and criticize the prosecution probe."

A district court previously sided with the eight prosecutors and ordered Chung to pay 16 million won in compensation, but an appellate court overturned the ruling.

Chung, the popular online critic of Lee who rose to national fame with a podcast lampooning the former leader, was released after serving one year in prison for spreading false rumors connecting Mr. Lee to allegations of stock fraud.

The Web celebrity, 53, was one of the four co-hosts of "Naneun Ggomsuda," or "I Am a Petty-Minded Creep." The weekly online talk drew a nationwide audience and became one of the world's most downloaded political podcasts from the Apple iTunes store. (Yonhap News)