The Supreme Court upheld a one-year prison sentence for the mother-in-law of President Yoon Suk Yeol for fabricating bank balance certificates and fraudulently signing a real estate contract.

In its ruling on Thursday, the top court said there is no legal error in the appellate court's conviction of Choi Eun-soon for forgery and violating the Act on the Registration of Real Estate under Actual Titleholder's Name.

Choi was indicted for colluding with a person surnamed An while buying land in Seongnam, Gyeonggi Province between April and October 2013 and falsifying documents purporting to show bank deposits totaling 34-point-nine billion won, or around 27 million U.S. dollars.

Choi was also charged for signing a contract under borrowed names, including that of An's son-in-law.

Both the first and appeals courts convicted Choi, with the latter putting her behind bars in July of this year citing the severity of her crimes and a risk of flight, keeping her imprisoned through next July unless she is released on parole or pardoned.