An appellate court on Thursday handed down a reduced sentence to Woo Byung-woo, a former senior aide to ousted President Park Geun-hye, in a corruption scandal that led to Park's removal from office in 2017.

The Seoul High Court sentenced Woo, who served as presidential secretary for civil affairs for Park from 2015-2016, to one year in prison for illegal surveillance of officials. The court cleared him of other charges, including dereliction of duty and a violation of the act on testimony before the National Assembly.

He was indicted in April 2017 on multiple criminal charges, including dereliction of duty and abuse of power, in connection with the scandal.

In February 2018, the Seoul District Court sentenced him to two years and six months in prison.

He was convicted of neglecting his duty to carry out a necessary inspection on the suspected irregular government approval of the establishment of two foundations controlled by Choi Soon-sil, Park's longtime confidante, among other things.

In a separate case, he was given a 18-month jail term in December for illegally surveilling public officials and others through the National Intelligence Service.

The appeals court has since merged the two cases together.

It concluded that inspecting Choi's foundations was not part of Woo's job, so he could not be found guilty of dereliction of duty.

"The defendant does not seem to have known the wrongdoings committed by the foundations," the court said.

He was also cleared of the allegation that he abused his power when trying to intervene in the work by a special investigator through high-ranking police officials. It also found him not guilty of denying to appear in a parliamentary audit session for testimony in October 2016.

He was allowed to walk free after the verdict, since he already spent a year in prison in connection with the case.

Three crucial figures involved in the high-profile corruption case have all been convicted and put behind bars.

Earlier this year, the Supreme Court upheld a 20-year prison term for Park on bribery and power abuse charges. Choi was sentenced to 18 years in prison on charges including abuse of power, coercion and bribery in June. Samsung heir Lee Jae-yong was sentenced last month to 2 1/2 years in prison for bribing the two. (Yonhap)