President Yoon Suk Yeol's mother-in-law was detained Friday after an appeals court upheld a lower court ruling that sentenced her to one year in prison for forging a financial document used in a land purchase deal.

The appellate court in Uijeongbu, northeast of Seoul, dismissed an appeal by 76-year-old Choi Eun-soon who demanded the prison sentence handed down to her in 2021 be reconsidered.

Choi was accused of falsifying her bank balance certificate in 2013 to make herself appear financially capable of purchasing a plot of land in Gyeonggi Province. The document was fabricated to look like Choi had 34.7 billion won ($27 million) in her account.

She is suspected of submitting another forged bank balance certificate to the court in her lawsuit to get back her down payment for the land in Gyeonggi Province.

Choi also broke the real estate law by using the name of her business partner's son-in-law in the contract for purchasing land.