The top court upheld a one-year prison term for Woo Byung-woo, the former senior presidential civil affairs secretary during the Park Geun-hye administration, for his role in the influence-peddling scandal.

The Supreme Court on Thursday finalized a lower court's ruling on conducting illegal surveillance through the state spy agency.

The court also upheld the acquittal of failure to prevent the scandal and obstruction of duty against Lee Seok-su, the former independent inspector under the presidential office.

Woo was sentenced to two-and-a-half years and a year-and-a-half for dereliction and obstruction of duty and illegal surveillance, respectively, in his first trial.

The appellate court, however, acquitted Woo of the dereliction and obstruction of duty charges, citing that he was likely not aware of the corrupt acts committed by Park's confidante Choi Soon-sil and then-senior economic secretary An Chong-bum.

Woo, who has already been detained for over a year, will not have to serve any more prison time.