The sentence against Yolanda Guadalupe Pena was handed down by Judge James Hawkins in Indio.
A jury found Pena guilty in June of one count each of murder, torture and assault on a child resulting in death, according to the Riverside County district attorney's office.
Pena, a resident of La Quinta, was also convicted of one count of inflicting injury on a child, relating to another daughter, who was 12 years old at the time of the crime, prosecutors said.On June 25, 2009, prosecutors said authorities responding to a 911 call went to Pena's home, where they found the 3-year-old, Delilah, lying unresponsive on the floor and her body already showing signs of rigor mortis.
A coroner's autopsy showed the girl sustained blunt-force trauma to the head and that she had multiple bruises on her face and head. Prosecutors also said 35% of her body, including her face, had second-degree burns. Injuries to her left hand caused severe scarring and the partial loss of three of her fingers, with the bone exposed on one finger, prosecutors said.
Prosecutors said Pena would duct-tape the girl's mouth, tie and tape her hands, and lock her in a storage bin in a closet. The girl was also forbidden to speak or look at family members, they said.
Prosecutors said an investigation revealed that Pena, who was married, had had an affair and that one of Pena's daughters told her father -- Pena's husband -- about the indiscretion.
Prosecutors claimed that Pena blamed the girl who was 12 at the time for the breakup of her marriage and blamed Delilah, who was fathered by the man with whom Pena had the affair, for keeping Pena and her former husband from reconciling.
Prosecutors said an 11-year-old daughter was forced to watch her sisters report their behavior to their mother and forced to exact punishment on her sisters, facing beatings herself if she didn't.