Deise Moura dos Anjos was found without vital signs during a morning check at a women’s state prison in the southern Brazilian city of Guaíba, in the state of Rio Grande do Sul, CNN affiliate CNN Brasil reported Thursday, citing local police.
“Immediately, the staff provided first aid” and called the emergency medical service, “which, upon arriving at the scene, confirmed her death,” the criminal police said in a statement.
“Deise was alone in the cell. The circumstances will be investigated by the Civil Police and the General Institute of Expertise,” the statement added.
CNN Brasil reported that Dos Anjos’ husband, Diego, asked for a divorce the day before her death.
The cake poisoning, which killed three people and hospitalized three others, occurred on Christmas Eve in the city of Torres in Rio Grande do Sul.
Large amounts of arsenic were found in the bodies of the women who died, and arsenic at levels 2,700 times higher than the permitted limit was found in the flour used to make the cake, according to the police.
Dos Anjos, who was arrested in early January and charged with triple homicide as well as three attempted homicides, was the daughter-in-law of one of the victims, 60-year-old Zeli dos Anjos, police confirmed at the time. Zeli made the cake, according to CNN Brasil.
Police previously told CNN that Dos Anjos had disagreements with her family for more than two decades.
CNN has reached out to local police for further comment.
CNN’s Duarte Mendonca, João Scavacin and Rosa Rahimi contributed reporting.