... Ms. Huong’s conviction relates to a high-profile case involving numerous family members of Khaou Phallaboth—one of Cambodia’s richest businessman. Ms. Huong claims to have been married to him between 2004 and 2012, although he has publicly renounced her and said she was only his mistress.

The Khaou family controls one of Cambodia’s largest business empires, with holdings in real estate, construction and agriculture. The commerce minister, Mr. Chanthol, became a member of the family when he married Sun Sotha, the daughter of its octogenarian patriarch, Khaou Chuly.

After a high-profile trial that ended in February 2011, Khaou Seng Chenda, 50, the wife of Mr. Chuly, was sentenced to 20 years in prison over the alleged plot to rape and murder Mr. Chanthol’s wife and daughter.

The decision was upheld by the Appeal and Supreme Court and, despite a dearth of material evidence and a reliance on inconsistent witness testimony, three accomplices of Ms. Seng Chenda also received sentences of 18 to 20 years.

According to the court, the accomplices, two of whom were maids, conspired with Ms. Seng Chenda to ensure access to the villa owned by Mr. Chanthol and Ms. Sotha on the night of the planned rape and murder in June 2010.

None of the suspects were seen at Mr. Chanthol’s villa on the night of the apparent plot, however, and no harm ever came to his wife or daughter. The only physical evidence of the crime was a window left ajar by a maid, which Ms. Sotha later closed, foiling the conspiracy.

Ms. Seng Chenda, the wife of the Khaou family patriarch, said on the day of her conviction that the rape and murder plot against Mr. Chanthol’s family had been fabricated.

“They accused me of wanting to kill Sun Sotha because I am afraid that Sun Sotha will inherit my husband’s property,” she said at the time. “But it is wrong because my husband has 12 children. If I kill one, there are still 11 remaining. So, must I kill all of them?”

Mr. Chanthol, however, denied that the rape-murder plot against his wife and daughter was fabricated in order for his family to more easily secure the Khaou family riches.

“Please let me say that Sun Chanthol and Sun Chanthol’s family do not want one cent from Okhna Khaou Chuly,” Mr. Chanthol said when the decision was upheld.

The alleged role of Ms. Huong in the rape and murder plot—aside from her link to a Khaou family member in Mr. Phallaboth—has never been made clear by authorities.