After previously pleading guilty to second-degree murder, Ashley Denise Attson, 23, was sentenced on Monday to serve 20 years in prison for leaving her toddler daughter in the desert to die. The maximum sentencing, under a plea agreement, was imposed by Federal Judge David Campbell.

Attson, of Chinle, AZ, placed her 17-month-old baby in a stroller, wheeled her to the desert on the Navajo Reservation, and intentionally left her there to die in September 2016. She, then, met with friends for ice cream over the next few days, New York Daily News recounted.

She also posted photos of herself on Facebook, according to the Arizona U.S. Attorney’s Office statement. She did not return for her baby for four days and four nights, according to the New York Daily News.

Mom buried her baby in a trash bag

When Attson did go back to where she left her daughter, her child was dead. Attson put her baby in a trash bag and buried her “in an animal hole,” the U.S. attorney’s stated and Time reported.

Judge Campbell called the murder horrendous and cold-hearted. The child-killing mother will spend 20 years imprisoned. Following her release, she will have five years supervision.

Prior to when Attson pleaded guilty, federal prosecutors filed an order of detention in the U.S.

District Court (Flagstaff). Two of the reasons that prosecutors cited for keeping Attson in custody were: her prior criminal history and her record of failing to appear in court. The most recent time Attson failed to appear was in September 2016, the month she ensured her baby would die alone in the Arizona desert. Additionally, the detention order stated that she has mental health concerns and a history of substance abuse.

Federal Judge Deborah M. Fine signed the detention order.

Baby born addicted to meth

For the majority of her 17-month-old daughter’s life, the baby was in the custody of tribal social services. The toddler was born addicted to methamphetamine. Approximately two months prior to pushing her baby into the desert to die on the Navajo Nation, Attson regained custody.

Cosme Lopez, the spokesman for the U.S. attorney’s office, declined to comment respective of Attson’s motive for killing her toddler, according to KCRA.

Lopez also stated that he was unable to provide any additional information relating to the circumstances of the baby’s death. He cited Department of Justice policy as the premise for not being able to release the baby’s name since she was a juvenile. Court records only reference the toddler as “Jane Doe,” according to KCRA.

Former Navajo Nation tribal prosecutor ‘troubled’ by length of prison sentence

Bernadine Martin is a former chief tribal prosecutor for the Navajo Nation. Martin said she is “troubled” that Attson was sentenced to serve a 20-year prison sentence when she could have received a life sentence resulting from her guilty plea, KCRA reported.

Martin also said that the baby was undoubtedly in physical distress and afraid. Her mother was the one person the toddler needed most. Martin added, “20 years is simply not enough.”