An Arizona woman was sentenced to death after being found guilty of murdering her young cousin.

Sammantha Allen was convicted of helping her husband, John Allen, lock 10-year-old Ame Deal in a box as punishment overnight on 12 July 2011. The Allens punished Deal because the young girl took a Popsicle from the freezer without permission, the Phoenix New Times reported.

Deal suffocated and was found dead the following day as temperatures surpassed 100F degrees. Prosecutors said the box only had small holes near the handles for air.

The couple originally claimed the girl hid in the box during a game of hide-and-seek and that she suffocated accidentally. They later confessed to putting the girl in the box and padlocking it shut.

During the trial, the court heard about the other abuse Deal was subjected to during her short life. Jurors were told she was forced to eat dog faeces and walk barefoot on the pavement in 114F degree heat.

Sammantha was also found guilty of child abuse, intentional or knowing child abuse and negligent child abuse, ABC15 reported. Her defence team claimed that the harsh punishments were normal in her own childhood home and said she followed the example of her mother and Deal's legal guardian, Cynthia Stoltzmann.

Stoltzmann and Deal's grandmother, Judith Deal, both admitted to previously locking the girl in the box as punishment. According to CBS 5, Stoltzmann was convicted of attempted child abuse and sentenced to 25 years.

David Deal, the 10-year-old girl's father, also pleaded guilty to attempted child abuse and was sentenced to jail.

Sammantha Allen is the third woman on Arizona's death row, the New Times reported. She will be kept in solitary confinement for 23 hours a day. No woman has been executed in Arizona since the failed hanging of Eva Dugan in 1930.

John Allen's trial began this week. He is also charged with murder and child abuse.