By David Schwartz

PHOENIX (Reuters) - An Arizona woman was sentenced to death on Monday for killing her 10-year-old cousin, who was locked inside a small storage bin as punishment for taking a Popsicle without permission.

A Maricopa County jury deliberated for more than a week before returning the verdict against Sammantha Allen in the July 2011 suffocation death of Ame Deal at the child's Phoenix home, court officials said.

Allen, 29, was convicted in June of first-degree murder and child abuse for leaving the child locked inside a plastic storage bin overnight in triple-digit temperatures. The girl was found dead the next morning.

Allen's attorney could not immediately be reached for comment following the sentencing in county Superior Court in Phoenix.

“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,” said County Attorney Bill Montgomery.

Prosecutors are also seeking the death penalty against her husband, John Allen, who has pleaded not guilty to murder and child abuse charges in the girl's death. His trial is scheduled to start on Oct. 9.

Allen will be the third woman on Arizona's death row.

The state has executed one woman in its history, Eva Dugan who was hanged in 1930, prison officials said.

Arizona has not executed an inmate in three years since an execution took nearly two hours. It resulted in a lawsuit by several inmates who claimed the process caused prolonged suffering. The state has said it does not have the drugs to perform an execution.

Police said the child, left in the Allens' care, was forced to perform intense physical exercise for several hours during scorching summertime temperatures for stealing the frozen treat from the refrigerator.

The married couple then ordered her to get the hinged, plastic container and climb into it, police said. Sammantha Allen watched as her husband padlocked the girl in the box and the couple then fell asleep, police said.

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The dead girl's body was found inside the small container that prosecutors at the trial said only had tiny air holes at its handles.

Family members initially told police that Deal's death was the result of a hide-and-seek game that turned tragic. That story unraveled during a police investigation.

The girl's aunt and legal guardian, Cynthia Stoltzmann, who is Sammantha Allen's mother, was convicted in the case and is serving 24 years in prison for child abuse. Police said she was not present when the girl was locked in the storage bin.

(Reporting by David Schwartz; Editing by Ben Klayman)