Lim. 59, was arrested on Oct. 27.

Lim is suspected of being the key man who helped former Supreme Court Chief Justice Yang Sung-tae use trials as bargaining chips in dealings with the presidential office under then President Park Geun-hye's government to win Park's approval to establish a separate court of appeals, Yang's long-envisioned dream.

Prosecutors also announced they summoned Park Byong-dae, an ex-Supreme Court justice who headed the NCA from 2014-16, for questioning next Monday over his alleged involvement in the scandal.

They hinted at a plan to call in Ko Young-han, NCA chief from 2016-17, for an interrogation in the same week they are to probe Park and eventually bring Yang in for questioning as early as the end of this month.

Prosecutors accuse Lim of carrying out Yang's schemes to interfere in ongoing trials whose rulings would have had a large political impact on the conservative government and to exert pressure on judges in charge to deliver a verdict in Park's favor.

Lim worked for the NCA from 2012-2017.

Among the trials in question are the compensation case of Korean victims of Japanese wartime forced labor, which had been held up at the top court for five years, and a case involving a progressive teachers union.

Prosecutors suspect that Lim worked out ways to postpone the Korean victims' damages suit against a Japanese firm and helped the foreign ministry with its argument against the victims, in line with Park's foreign policy toward Tokyo.

South Korea's Supreme Court resumed the trial this year and ordered on Oct. 30 that Nippon Steel & Sumitomo Metal Corp.

compensate the victims for the forced labor.  (Yonhap)