The People v. Elizabeth Duncan trial was heard at the Superior Court of California in Ventura County regarding the murder of Olga Duncan by Augustine Baldonado and Luis Estrada Moya at the behest of Olga Duncan's mother-in-law, Elizabeth Ann Duncan. All three were tried for the murder, convicted, and in August 1959 executed for the murder.

Elizabeth Duncan, 54, introduced her son, Frank, to Olga while receiving care at Santa Barbara’s Cottage Hospital. Frank and Olga later married. Duncan was very jealous of her son, and Frank, who lived with his mother, did not initially tell her that they had married in June 1958. At one point Duncan impersonated Olga and hired someone to impersonate Frank in order to get the marriage annulled. Upon learning that Olga was pregnant, Duncan looked for someone to kill her daughter-in-law.

She met with Baldonado and Moya, who were from Ventura County, and offered them $6,000 to kill Olga although she never intended to pay them. On November 17, 1958, Baldonado and Moya lured Olga from her Santa Barbara apartment into their car by telling her that Frank was passed out drunk in their car. The two men kidnapped and buried Olga along Highway 150 in Ventura County near Casitas Pass. There was evidence that suggested she may have been alive when they buried her.

As Duncan was unable to pay the two men, she went to the Santa Barbara Police Department to report them for extortion. She later attempted to drop the charges. After speaking with Moya and Baldonado the police discovered enough evidence to arrest Moya and Baldonado for Olga’s murder. They confessed and led police to Olga’s grave and implicated Duncan in the murder.

The trial drew national attention and is often known as the Ma Duncan case. Duncan was the last woman to be executed in the state of California. Frank stood by his mother throughout the entire trial, which was the subject of much speculation and rumors regarding the nature of their relationship. Both Maldonado and Moya confessed and testified against Duncan without receiving a plea deal. All three were executed in San Quentin prison on August 8, 1962.