RICHARDSON (CBSDFW.COM) – More than a month after toddler Sherin Mathews disappeared in Richardson and was later found dead both of her adoptive parents are in jail. The 3-year-old’s mother, Sini Mathews, went before a judge this morning.

Sini Mathews is facing the felony charge of abandoning or endangering a child and is being held in the Richardson Jail. The 35-year-old woman was arraigned on Friday.

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Mitch Nolte, one of the attorney’s representing Sini Matthews, told CBS 11 News that his client is afraid and upset, but is trying to keep it together for her surviving biological daughter.

In video seen only on CBS 11, Sini Mathews had her attorney by her side when she walked into the Richardson Police Department to turn herself in Thursday afternoon.

The abandonment charges center around investigators belief that Sini left Sherin home alone for more than an hour, while the rest of the family went to a restaurant in Garland and ate dinner.

According to a police report, a dinner receipt on the evening of Friday, October 6 showed one child’s meal was purchased and the waiter remembered only one child at the restaurant with Sini and her husband Wesley Mathews that night. The child with the couple is believed to have been the couple’s 4-year old biological daughter.

(credit: Richardson Police Department)

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Richardson police Sergeant Kevin Perlich said the charge is, “…not necessarily related to her [Sherin’s] death. It’s related to the care she was given while in that home.”

According to a police report, Wesley Mathews said the couple left the toddler at home alone because she wasn’t drinking her milk. It was more than an hour later when he said they returned home to find her “still in the kitchen alive and well.”

When Wesley Mathews was initially arrested he told police that he was punishing Sherin for not drinking her milk and that at 3 a.m. he ordered her outside to stand by a tree about 100 feet outside their backyard. He said he left the little girl there and when he returned 15 minutes later discovered she was gone.

Wesley Mathews later changed his story claiming that he was trying to get Sherin to drink her milk, but that she wouldn’t listen to him and when she finally complied he “physically assisted her in drinking the milk.”

Mathews told investigators that the toddler began to choke and after coughing for a while her breathing slowed. He said when he could no longer feel Sherin’s pulse he “believed she had died” and removed the body from the house.

Wesley Mathews is charged with Injury to a Child and is being held on $1 million bail.

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While both Wesley and Sini Mathews are behind bars investigators still do not know how their daughter died. The Dallas County Medical Examiner’s Office has yet to release an official cause of death for Sherin Mathews.