Allen, 29, was convicted of first-degree murder and four counts of child abuse for making her young cousin exercise in the sweltering Arizona heat and then padlocking her in the box, which measured just 31 by 14 by 12 inches.
It was the end of Ame’s brief, abuse-filled life in a crowded home in south Phoenix, prosecutors argued.
She had been the victim of physical abuse, including being kicked in the face and beaten with a wooden paddle.
The adults in the house made Ame drink hot sauce, eat dog feces and crush aluminum cans with her bare feet.
The night she died, in July 2011, wasn’t the first time her relatives had forced her into the plastic storage box to punish her. At the time, the temperature exceeded 100 degrees.
Allen was found guilty June 26, according to the Republic.
For more than a week, a jury deliberated to determine whether there were mitigating factors that meant she shouldn’t be given the death penalty — including her own dysfunctional upbringing and her age.
“Lack of remorse was the biggest thing that played into it for us, that we didn’t see that from Sammantha throughout the whole process,” juror Anne Schaad told CBS affiliate KTVK.
On Monday, the jury decided on the death penalty.
Cynthia Stoltzmann — Allen’s mother and Ame’s legal guardian — is serving a 24-year prison sentence for a child abuse conviction.
The trial of John Allen, Allen’s 29-year-old husband, is scheduled to start Oct. 9, according to the AP. He has pleaded not guilty to the same charges as his wife and also faces the death penalty.
David Deal, Ame’s father, was convicted of attempted child abuse and sentenced to jail, according to KTVK.
In the moments after they discovered Ame dead, the adults in the house concocted a story about a game of hide-and-seek going tragically wrong, the AP reported.
But the Allens eventually confessed to padlocking the girl in the box, where she died.
Sammantha Allen becomes the third woman on Arizona’s death row, and the first since 2011, when Shawna Forde was sentenced to death, according to the Arizona Republic.
After the jury’s verdict was read in Allen’s case, she hung her head and wept. Her attorney, John Curry, told reporters: “I just feel sad.”
But Maricopa County Attorney Bill Montgomery told the Republic that condemning Allen to death was the correct decision: “I want to thank the members of the jury for their time and effort on this case and reaching a difficult but just conclusion for the senseless murder of Ame.”